Combining Photovoltaics with the Rewetting of Peatlands—A SWOT Analysis of an Innovative Land Use for the Case of North-East Germany

Abstract

Reducing emissions from energy production and enhancing the capacity of land use systems to store carbon are both important pathways towards greenhouse gas neutrality. Expanding photovoltaics (PV) contributes to the former, while the rewetting of drained peatlands preserves the peat soil as long-term carbon store, thus contributing to the latter. However, both options are usually considered separately. This study analyses Peatland PV, defined as the combination of open-space PV with the rewetting of peatlands on the same site, and has an explorative and field-defining character. Due to a lack of empirical data, we used expert interviews to identify the strengths and weaknesses, opportunities, and threats of Peatland PV in the sparsely populated and peatland-rich state of Mecklenburg-Western Pomerania in North-East Germany. The material was analysed using a qualitative content analysis and compiled into SWOT and TOWS matrices. Besides the ecological and technological dimensions, this study focuses on the economic and legal framework in Germany. We found that Peatland PV may mitigate land use conflicts by contributing to climate and restoration targets, energy self-sufficiency, and security. Continued value creation can incentivize landowners to agree to peatland rewetting. Technical feasibility has, however, a significant influence on the profitability and thus the prospects of Peatland PV. Although Peatland PV has recently been included in the Renewable Energy Sources Act (EEG), several specialised legal regulations still need to be adapted to ensure legal certainty for all stakeholders. Pilot implementation projects are required to study effects on vegetation cover, soil, peatland ecosystem services, biodiversity, hydrology, and water management, as well as to analyse the feasibility and profitability of Peatland PV.

1. Introduction

To achieve the goals of the Paris Agreement on climate change, many countries are aiming at CO₂ or greenhouse gas (GHG) neutrality, e.g., Germany by 2045 [1], the European Union by 2050 [2], and China by 2060 [3], among others. As a consequence, decarbonisation transformations are required in all sectors of the economy, in particular in the energy sector, the agriculture sector, as well as in the land use, land use change, and forestry (LULUCF) sector [4]. Energy production from fossil fuels needs to be replaced by renewable energies from solar, wind, water, biomass, and geological resources [5]. Land use systems must be transformed to reduce emissions and increase the carbon sequestration of land ecosystems [6]. Besides enhancing forestry and carbon farming, the conservation and restoration of peatlands have received a significant amount of attention as nature-based solutions [7]. Drained peatlands are considerable sources of CO₂ emissions, which can be significantly reduced if peatlands are rewetted [8]. Afforestation, rewetting of peatlands, PV plants, and wind power plants all require land, which unavoidably increases competition for land resources [9,10]. Combined land uses such as agrivoltaics (Agri PV) [11] and paludiculture [12] may reduce land use conflicts and are increasingly discussed (Figure 1). The idea of Peatland PV or Paludi PV entered the discourse only recently. Peatland PV combines open-space PV with the rewetting of peatlands on the same site, while Paludi PV describes an additional major agricultural use of the rewetted peatland site. Open-space PV (often also called solar park) refers to PV plants installed in open areas or fields either ground-mounted or floating. The delineation of the different land use types depicted in Figure 1 is not always easy and can be subject to scientific, legal, and political debates. For instance, although all ground-mounted open-space PV plants require biomass to be controlled or removed, which is a kind of agricultural activity, it is not meaningful to consider all of them as Agri PV. Thus, the significance of agriculture production that turns open-space PV into Agri PV, e.g., [13], or Peatland PV into Paludi PV, needs to be defined. We propose that Peatland PV requires the rewetting of the peatland and the control of growing biomass on the same site, but the agricultural use is of no or minor economic importance. This study focuses on Peatland PV, an innovative land use that is increasingly gaining attention in the social and political discourse in Germany [14,15,16].

The production of solar (or wind) power on drained peatlands is also a topic in other peatland-rich countries, e.g., Latvia [17] and Finland [18], but the necessary combination with rewetting [7] is often not considered. In Germany alone, 1.45 million hectares of drained peatlands used for agriculture need to be rewetted by 2050 at the latest to contribute to international climate targets set by the Paris Agreement and the European Green Deal [7]. However, since EU agricultural policy still supports agriculture on drained peatlands and paludiculture product markets are hardly developed yet, landowners and users are reluctant to rewet; they fear losses in income and land value [19]. At the same time, open-space PV recently became very profitable offering land rents far beyond land rents achievable through agricultural use [20]. However, spatial planning, building, and nature conservation regulations in Germany are quite restrictive and subsidies are provided for open-space PV only in specific areas, e.g., along motorways and railways. Thus, Peatland PV might be an option to enlarge the area available for PV while at the same time incentivizing the rewetting of peatlands.

Against this background, the objective of this study was to identify the strengths and weaknesses as well as the opportunities and threats of Peatland PV in Germany in order to derive strategies for its implementation. Due to a lack of empirical data on the practical implementation and scientific considerations of Peatland PV, this study mainly relies on expert knowledge, and thus has an explorative and field-defining character. The peatland-rich state of Mecklenburg-Western Pomerania (MV) in North-East Germany was selected as the study region since emissions of drained peatlands account for one-third of the total GHG emissions, and the rewetting of peatlands thus can considerably contribute to climate change mitigation [21]. At the same time, the sparsely populated region is already characterised by extensive renewable energy production, encompassing both wind and PV plants.

To the best of our knowledge, this study is the first to reflect in detail on Peatland PV based on expert assessment. Although it has a narrow geographical focus and refers to specific legal settings, we believe that the results have broader implications. Peatland PV is a relevant topic for all countries worldwide that aim to rewet drained peatlands. Our study can serve as a useful reference for other countries and future empirical research.

2. Materials and Methods

2.1. Study Area

The study area is North-East Germany. The focus was placed on the federal state of Mecklenburg-Western Pomerania (MV). The state government aims to achieve GHG neutrality by 2040 and considers peatland rewetting and the expansion of renewable energies as key areas of action [22].

Peatlands cover around 300,000 ha, which is about 13% of the land area of MV. Only 3% of the peatland area is in a near-natural state; rewetting measures have been conducted on about 10% of the peatland area [23]. The majority of the peatland area is drained and in productive use, 55% for agricultural purposes. The dominant land use is grassland mainly for suckler cow husbandry.

Open-space PV has been developing rapidly in MV, in particular since 2016. The State Spatial Development Plan (LEP-LVO M-V) offered the opportunity to build PV on agricultural land in a strip of 110 m along motorways, federal roads, and railways. In 2021, the state parliament decided that PV plants could be built on an additional 5000 ha of agricultural land, provided the projects meet certain requirements. In 2023, the 5000 ha limit had already been exceeded [24]. Despite the large area potential and first projects in preparation, no Peatland PV project has been implemented in MV until now (September 2024). To our knowledge, no Peatland PV projects – with intentional rewetting – have been implemented in other states of Germany either.

2.2. Thematic Dimensions of the Assessment

The assessment of innovative technologies or land uses, such as Peatland PV, can be carried out with reference to various thematic dimensions. PESTLE is a framework often used in assessing renewable energies or technologies, and it refers to political, economic, social, technological, legal, and environmental/ecological dimensions, e.g., [25,26]. This research focused on the following four dimensions (ETEL) of Peatland PV:

(1)

Ecological;

(2)

Technological;

(3)

Economic;

(4)

Legal.

Social and political dimensions are not investigated in detail but are partly addressed under the economic and legal dimensions.

2.3. Literature Review

Scientific literature, such as journal articles related explicitly to Peatland PV, was not available until the beginning of 2024, upon searching in scientific search engines such as ‘Web of Science’, ‘Google Scholar’, and the database ‘Research Gate’. Grey literature like statements and reports from politics and associations, as well as legal texts, was used for the description of the current state of knowledge on Peatland PV and the contextualisation of the results. Especially, the legal framework has been developing dynamically in Germany from the years 2022 to 2024. Given the high topicality of Peatland PV and the resulting lack of literature, this study was primarily based on interviews with experts.

2.4. Expert Interviews

The interviews needed to cover the most important aspects related to Peatland PV implementation, such as nature conservation and peatland protection, implementation of PV systems and geotechnics, eco-account measures and land management, agriculture, and law. Possible interview partners within the different groups of experts were identified using the snowball principle [27] (p. 59). When selecting the experts, care was taken to ensure that different areas of expertise, and thus, perspectives on Peatland PV were represented. There were also refusals to participate in the interviews, one with reference to an ongoing internal evaluation of the topic from a nature conservation perspective and one due to the individual categorical rejection of Peatland PV due to ecological and legal concerns. Finally, ten experts were recruited for an interview (

Table 1. Overview of the ten experts interviewed, arranged and numbered in the order in which the interviews were conducted.

No.	Role/ Function	Institution
1	Expert with specialisation in peatland protection projects, the water framework directive, and approval procedures for PV plants	Lower Nature Conservation Authority
2	Expert responsible for the political representation of the farmers’ interests with a focus on agricultural production and renewable energies	Farmers’ Association
3	Expert with specialisation in nature conservation funding projects, eco-account measures, and intervention compensation measures, including peatland rewetting	Land Agency
4	Expert from a consulting agency for public authorities, companies, and citizens	Regional Energy and Climate Protection Agency
5	Expert in environmental engineering with specialisation in the realisation of PV systems	Renewable Energy Company I
6	Expert with specialisation in peatland conservation, ecosystem services, education for sustainable development, and eco-value certificates	Highest Authority for Climate Protection, Agriculture and Nature Conservation
7	Expert with specialisation in project development of PV systems	Renewable Energy Company II
8	Expert from a leading research institute in the field of peatlands	Research Institute for Peatlands
9	Expert in civil engineering with specialisation in geotechnics, tunnelling, and construction management	Geotechnics Company
10	Expert in agricultural law	Law Firm

). All selected experts were based in MV, or their institutions were at least active within the state of MV. This selection process ensured a diversity of expert perspectives on the different dimensions of Peatland PV. It also allowed for data triangulation since, per dimension, more than three experts could always give an informed assessment. Please note that it was not our objective to aim for representative expert opinions in any statistical sense; instead, we tried to select the most knowledgeable experts while ensuring diversity, relevance, and coverage. It should be further noted that the interview partners are not only experts with special knowledge and skills in their subject area but also stakeholders who have an interest in the object of study, are directly affected, or have an active or passive influence on decision-making and implementation processes due to their position [28] (p. 341). In the following, the term ‘expert’ is meant to include both perspectives of the interviewee — his or her knowledge and experience as an expert, as well as his or her interests as a stakeholder. The experts were interviewed because of their professional backgrounds and not as private persons. Although they were selected as representatives of their institution, they do not inevitably always represent its point of view.

The semi-structured expert interviews were conducted and recorded in online video conferences between March and July 2022. The interview length varied between 30 and 90 min. Guidelines provided a structure to ensure that the points relevant to the research question were addressed cf. [29] (p. 677). A small number of questions were asked in a standardised way to all experts, with the majority of the questions focusing on the individual areas of expertise, as well as the insights required in a specific area or thematic dimension. Input for other dimensions was also recorded and evaluated accordingly.

2.5. Data Analysis

The audio recordings were transcribed for further analysis. A qualitative content analysis [30] was conducted using the computer software ATLAS.ti 9. For the evaluation of the texts, codes for the ETEL dimensions were developed inductively on the material in a first manual processing round and assigned to the individual text passages. In a second round, the codes were applied to further text passages. Redundant codes were identified and deleted, moved, or merged. In addition, hardly reused and irrelevant codes were removed cf. [30] (p. 634). The coding was implemented by the first author, while copies of the coded data were given to all members of the research group for critical review. Thus, co-authors functioned as examiners and auditors of the analysis [31] (p. 37). Since our goal was to reach a consensus about the interpretation of the content, we refrained from developing a numerical reliability rating [32]. If expert statements are used in the results section, the number of the interview, according to Table 1, is placed in round brackets. The second number in round brackets refers to the position of the statement in the transcript. Moreover, controversial opinions are clearly indicated, and when necessary, expert statements are sometimes complemented with additional factual background information.

2.6. SWOT and TOWS Analysis

SWOT analysis is a well-established tool of strategic management and is useful for supporting strategic decisions since both internal and external system characteristics are systematically evaluated [33,34]. Internal factors are identified as strengths (S) and weaknesses (W) compared with other competing systems. External factors refer to the environment which can create opportunities (O) and threats (T) for the respective system [35]. Qualitative assessment and the strategic grasp of the situations enable decision-makers to assess measures to use strengths, balance weaknesses, identify opportunities, and avoid threats [36].

In this research, the SWOT analysis was applied to an innovative combination of land uses. Internal factors tended to be categorised as aspects that distinguish the specific implementation site or the combination of land uses from other competing land uses on the same site. External factors were defined as those that have an impact beyond the immediate sphere of influence of the individual implementation site. A separate SWOT matrix was created for each of the four dimensions considered in this study.

The results of the SWOT analysis can be used in a further step to derive recommendations for action. The so-called TOWS matrix [37] is a conceptual model that relates the factors of the SWOT matrix to each other, i.e., (1) to leverage strengths to benefit from opportunities (SO), (2) to overcome weaknesses by seizing opportunities (WO), (3) to use strengths to protect against threats (ST), and (4) to overcome weaknesses by minimising threats (WT) [37]. In this paper, a TOWS matrix was created including all four previously analysed dimensions — ecological, technological, legal, and economic — to account for interdimensional relations and to formulate outlooks and recommendations for action. The SWOT and TOWS analyses have already been widely used to assess the transition towards renewable energy (e.g., [38]), solar power (e.g., [39]), and agrivoltaics (e.g., [40]) in different countries and contexts, but not to Peatland PV yet, to the best of our knowledge.

At the end of each interview, all experts were asked about their final overall assessment of the opportunities and threats for Peatland PV. Scale values from 1 (threats very much predominate) to 10 (opportunities very much predominate) were possible.

3. Results

3.1. Ecological Dimension

The ecological dimension of Peatland PV is multifaceted. Just as with peatland conservation in general, different aspects like the hydrology of the specific implementation site, species protection, soil conservation, and climate change mitigation are concerned. Possibilities of general statements are limited, as the conditions are usually very site-specific (1:12).

3.1.1. Perspectives on Peatland PV Differ According to the Reference

Climate change mitigation and nature conservation are not the same, as the nature conservation expert emphasises (1:45). A highly degraded peatland, e.g., drained and intensively managed grassland, will be upgraded through rewetting, despite the construction of PV modules (1:45). From a nature conservation perspective, this enhancement is certainly not comparable with pure rewetting, but the reference here is ultimately the continuation of intensive drainage-based land use (1:45). Wet peatlands, including rewetted peatlands, despite of being permanently altered due to the drainage history, can offer a variety of other ecosystem services in addition to the carbon store function (8:18). These include for instance groundwater retention, water storage and water quality improvement, evaporative cooling, and flood protection (8:18). Whether rewetted peatlands can also provide these services to a comparable extent when combined with PV needs to be openly investigated for specific Peatland PV project sites, different peatland types, and different regions (8:19).

3.1.2. Hydrology of Peatlands and Climate Change Mitigation

The positive effects of the peatland rewetting due to the preservation of peat as a long-term carbon store are mutually agreed on by the experts (1:103; 2:16; 3:20; 6:25; 8:38). Though the degree of rewetting associated with Peatland PV is a central point of discussion for all experts. Especially, the PV experts expressed the need for clarification on the specific water level on the site since it influences trafficability and project feasibility (5:33; 5:86). In this context, some experts raise concerns that water levels might only be partially raised to 30 cm below the surface or even lower in order to meet technical requirements, while optimal climate effects are not met (3:20).

The representative of the Farmers’ Association assumes that active water management on site allows for continued fodder production, which does not correspond to full rewetting (2:71; 2:74; 2:77). Yet only full rewetting with water levels close to the surface can reduce CO₂ emissions to zero, achieve an optimal climate effect, and stop land subsidence (1:103; 3:20; 8:38).

Peatland experts are sometimes criticised by nature conservationists for considering a combination of rewetting and open-space PV (8:20). Concerns have also been raised that the possibility of Peatland PV could lead to pressure to also cover already restored sites with open-space PV (3:22). At the same time, 530 ha of drained peatland in Germany have already been built over with open-space PV without rewetting (8:20, June 2022). This is a problem and must be prevented in the future (8:20). According to the expert of the highest public authority on nature conservation and agriculture, Peatland PV should only be implemented on previously drained peatlands in combination with rewetting: full rewetting with optimal emission reduction should be a fundamental criterion (6:20; 6:25). Experts argue that selecting suitable peatlands is crucial for rewetting, as the specific type of peatland and hydrology of the site in combination with the adjacent infrastructure, such as villages and roads, can already limit possible rewetting (1:94; 2:66; 2:38; 2:66).

3.1.3. Effects of Shading on the Vegetation

The peatland expert considers the influence of shading by the PV modules as a relevant factor (8:24). Depending on the construction method of the PV modules, shading of the peat body can vary strongly between 50 and 80% (1:23). Even in the case of conventional elevated PV constructions, diverse vegetation can form, according to the PV experts (5:15), as sufficient light still reaches the ground underneath the modules (7:88). In the case of Peatland PV, the specific effects on microclimate and vegetation are still uncertain due to the lack of scientific assessments (1:23; 3:16). Furthermore, vertical elevation and larger row spacing of PV modules could be comparatively more beneficial for flora and fauna (1:108). It is important, though, to consider the ecological benefits in comparison with the economic costs (1:108). In addition, reduced solar radiation and thus reduced evaporation could have positive hydrological effects on the peat body (4:11).

3.1.4. Nature Conservation, Species, and Soil Protection

Species protection (for both plant and animal species) must be considered (9:21), since rewetting always includes opportunities for the entire biocoenosis and species diversity, e.g., the diversity of insects (1:13). One expert doubts that Peatland PV brings the same added value as pure rewetting (3:66). However, under the policy framework of recent years, it is unlikely that the policy goals for peatland restoration can be met without any combination with other land uses (3:68).

Possible risks to species conservation are debated: The peatland expert sees minimal risks for species conservation in the case of Peatland PV, as rewetting would presumably even result in greater biodiversity than previously existed on intensively used and species-poor arable land or grassland (8:24). Nevertheless, rewetting and construction with PV will impact individual species that previously inhabited the site. However, the reference is not a near-natural peatland but the continued use of a degraded peatland. Therefore, this is ultimately a trade-off between currently existing species on the site and peatland-related species returning after rewetting (8:24).

Other effects, such as large reflective surfaces of the PV modules with an impact on migratory birds also apply to open-space PV on mineral soils and are not specific to Peatland PV (8:25). The problem of collisions with PV plants is not as great as with wind turbines, or at least there is no comparable data basis available yet (8:25).

The lower public authority conservationist emphasizes the importance of grassland for fauna, particularly avifauna like the white stork (Ciconia ciconia), as one of the main reasons for the rejection of many open-space PV plants in the past (1:10). If more sites will have to be opened up for PV construction in the future, sites with hard exclusion criteria for species protection, like eyrie protection zones, should continue to be excluded from PV construction (1:132). The representative of the Farmers’ Association believes that Peatland PV in protected areas should not be excluded in principle but calls for a case-by-case assessment concerning the specific conservation objective (2:46). Another expert fears a future threat of pressure to use areas that already have been rewetted, although the exclusion of these areas can be assumed (3:22). PV plant installation poses potential risks to vegetation and soil compaction. However, the geotechnical engineer argues that these risks can be managed through thorough project preparation and the use of special machinery to minimize negative impacts (9:67). For the expert from the highest public authority for nature conservation, the bottom line is that Peatland PV is to be welcomed if there are no nature conservation concerns on the specific site (6:21).

3.1.5. SWOT Analysis on the Ecological Dimension of Peatland PV

The ecological dimension is summarised and structured in the following SWOT matrix (

Table 2. SWOT matrix on Peatland PV in the ecological dimension.

Strengths	Weaknesses
Restoring the ecosystem services of peatlands through rewetting → Carbon store function, i.e., preservation of the peat layer as long-term carbon store → Water retention function Establishment or return of peatland-specific species Possibly reduced evaporation due to shading (not yet quantified)	Trade-off due to displacement of established species and habitat types through rewetting, e.g., resting and feeding areas for birds Negative impacts of open-space PV in general (e.g., effects of large reflective module surfaces on migratory birds) Possibly reduced vegetation growth due to shading (not yet quantified) Soil compression due to construction work and machine traffic Disturbance or destruction of vegetation due to construction work
Opportunities	Threats
Reduction in GHG emissions in the land use sector and contribution to climate change mitigation Peatlands as water retention areas in the event of heavy rainfall events/ flooding Counteraction against biodiversity crisis and support for restoration targets	Incomplete rewetting (only elevation of water levels and continued release of GHG emissions) Potential pressure on or threat to already rewetted areas

). The ecological strengths of Peatland PV are mainly due to rewetting. Peatland ecosystem services can be restored, which often leads to an improvement of the site and creates opportunities to achieve larger-scale societal ecological objectives. Although benefits for peatland biodiversity are expected, the possible displacement of protected species that are not typical for peatlands can be assessed as a weakness. Additional weaknesses are mainly related to the necessary construction work and its negative consequences for vegetation and soil. The effects of shading by the modules on evaporation and thus on the landscape water balance and vegetation cover could be a strength or weakness but still need to be quantified. Ecological threats are identified as insufficient rewetting if water levels are set too low and there is potential future pressure to utilise already restored areas.

3.2. Technological Dimension

The technological dimension, like the ecological one, is site-specific, as certain local conditions may require different technical solutions. Only a limited number of generic statements and considerations for implementation could be made by some of the experts. These technical framework conditions are especially relevant for the economic dimension of the Peatland PV assessment.

3.2.1. Project Planning and Geological Analysis

Ground-mounted open-space PV projects begin with geological investigations during the planning phase, followed by a feasibility study during the approval process (9:25). This combines a desktop study with initial field parameters. Additional investigations are needed for construction and installation. These include in situ pile load tests, as well as mechanical and chemical soil investigations (9:25).

Compared with conventional open-space PV, only some soil parameters can be determined in the planning phase under drained conditions. These include soil chemistry, i.e., the acidity or salinity of the soil, as well as the degree of decomposition of the peat, among others (9:36). Other parameters, such as soil stability, are strongly influenced by water content. Especially when building with small piles, comparative tests and test loads in a wet state are necessary (9:39).

Overall, site- and project-specific considerations should be made for each peatland regarding the durability of the construction in chemical terms, as well as in terms of load-bearing capacity and foundation depth (5:51; 7:31; 9:33). Right from the planning and implementation stages, the peatland rewetting and PV installation measures should be considered together and implemented in parallel (1:136; 2:55).

3.2.2. Adaptation of Construction Equipment, Infrastructure, and Soil Protection Measures

Due to the changed, softer soil conditions resulting from rewetting, many experts expect various challenges. In particular, they point to the necessary stability of the ground-mounted PV plants and the accessibility of the rewetted site for machinery (2:17; 3:15; 4:24; 4:65; 5:35; 5:82).

Similar to paludiculture (6:40), the reduced accessibility for heavy machinery and construction equipment requires adapted technology (7:48; 9:43). For example, converted snow groomers with particularly wide tracks and consequently lower soil pressure could help to protect the soil and vegetation as much as possible (9:67). For the initial pile-driving work, the use of normal tracked construction equipment should be sufficient in most cases. For delivering material by truck, additional ground protection mats would be necessary (9:70).

Special construction equipment is still only available in small numbers in Germany (9:43). This increases the effort and cost of providing and delivering suitable equipment for construction (9:43). Nevertheless, the production of adapted machines for the construction phase is possible and comparatively uncomplicated for established mechanical engineering companies that build such crawler tracks (9:94). Another idea is to prestructure sites by creating backfills with accessible paths so that other partial areas do not have to be driven over. Additional costs would have to be expected here too (5:85).

The PV expert points out that an access road must be suited for the delivery and removal of a transformer station weighing at least 20 tonnes, as well as for the dead weight of the heavy-duty crane weighing at least 40 tonnes. For maintenance and repair, the accessibility and trafficability for a heavy-duty crane must also be permanently given (5:76). Major problems with Peatland PV for electricity connections via cable routes are not expected (5:111).

3.2.3. Installation and Foundation of the Modules

In addition to the consequences for trafficability, the changed ground conditions due to rewetting also have an impact on the installation and foundation of the constructions. The stud frames would have to provide sufficient support for the dead weight of the modules and possibly additional snow loads, as well as enough resistance to wind and its potential lifting forces (5:37; 5:54).

A PV plant is composed of several parts, including the substructure with foundations. If the foundations need to reach mineral soil below the peat layer and if the modules possibly need to be lifted higher above the vegetation, the driving posts might have to be longer accordingly (5:45; 9:97). Handling the driving posts would become very difficult. In addition, the softer ground conditions could require smaller distances and thus a higher number of driving posts (5:45).

The assessment of the changed conditions for the installation of Peatland PV in comparison with open-space PV on drained peatland is a matter for a geologist and specialist in soil foundation and rewetting (5:30). The geotechnical engineer gives insights into the technical consequences for full rewetting in combination with Peatland PV: (a) the bending moments of the posts due to wind load are maximised just below ground surface, (b) the corrosion attack due to the increased atmospheric oxygen input at the ground surface is maximised, and (c) in the case of rewetting with mean water levels close to ground level (0 to 40 cm below the surface), the negative effects in terms of bearing capacity reduction are maximised (9:82). Nevertheless, according to the geotechnical engineer, there are technical solutions to all these problems; hence, complete rewetting can be considered the norm for Peatland PV — especially in consideration of the other ecological benefits (9:83). The peatland expert uses the analogy with the construction of wind turbines in the sea and floating PV on lakes to illustrate that the construction of PV on wet peatlands must also be technically feasible (8:39).

3.2.4. Durability and Service Life of Materials

The standard materials used in the construction of open-space PV plants are conventional and highly cost-effectively optimised steel posts or small piles with variable zinc coatings (5:65; 9:22). Special or thicker coatings of the substructure might be necessary to achieve suitable corrosion protection (7:24; 9:44; 9:57). According to the geotechnical engineer, steel corrosion is difficult to predict despite existing literature values. With the exception of polymer coatings, this is mainly a matter of probability (9:73). However, the available experience regarding chemical resistance is sufficient to realise the 30-year service life that is now common in bank financing (9:76).

Besides special coatings, there is even a possibility of the development of new construction methods based on alternative building materials (9:22). For example, flat-roof PV construction methods could be adapted to peatlands. Dolphins, i.e., piles driven into the seabed as fixing points or as protecting structures, are already made of plastics in coastal regions of the Netherlands (9:47).

3.2.5. Maintenance, Care, and Mowing

Within the technological dimension of Peatland PV, maintenance and care are also considered critical factors by several experts (1:114; 2:17; 3.24). Maintenance is carried out at least once a year for standard constructions (5:68). The interval of inspections would potentially have to be shortened in the case of difficult site conditions, such as greater corrosivity and ground movement (5:72). This also means that the accessibility of the site has to be ensured to a greater extent, both for the maintenance team and for the transport of repair materials. Such inspections regularly take place in spring and autumn, but not during the main production period (5:72).

While no advantages or disadvantages were mentioned for cleaning the modules compared with conventional open-space PV (5:79), keeping the vegetation short in the case of Peatland PV raises new questions (3:17). Since sheep grazing is no longer possible after full rewetting with water levels close to the surface, technical mowing between or under the modules might be necessary (9:34), which is also standard practice for conventional open-space PV (7:91). The modules should not be shaded, e.g., by reeds growing tall (1:25).

Adapting mowing and harvesting technology for Peatland PV is similar to paludiculture. The development and provision of new technology is costly but manageable (6:40). The geotechnical engineer also sees a greater maintenance effort but no insurmountable challenges (9:89). For mowing, it might be necessary to manufacture smaller machines, e.g., beam mowers for the work under the modules (9:94).

3.2.6. Dismantling

When planning the Peatland PV plant and its dismantling, it should be assumed that the area will remain permanently rewetted and that there is no possibility of short-term drainage. Therefore, the dismantling process must also be feasible in wet conditions (5:96). The same equipment that would be used for installation could also be used for deconstruction. The pile driver with appropriately wide crawler tracks with a reverse start function, and so-called ‘impact reversal’ could drive the piles out of the ground just as well as they were driven in. On this basis, the geotechnical engineer estimates that the challenges of deconstruction are just as surmountable as those of installation (9:103; 9:106).

3.2.7. Alternative Construction Methods

Most experts referred to the conventional ground-mounted construction method with elevation on steel piles, even though floating structures on flooded sites could be an alternative construction method for Peatland PV (4:29). One PV project manager estimates the benefit of floating construction for Peatland PV to be rather low: Technical solutions are conceivable in principle, but the sites would have to be comparatively large and, above all, evenly structured (5:58). The peatland expert points out that shallow lakes are subject to greater water level fluctuations than other lakes and the PV modules could sink uncontrollably in summer if evaporation is very high (8:44).

Other construction methods, such as plastic troughs or areal foundation elements that are resting on the ground surface, might face problems like subsidence and lifting forces (5:54; 9:97). According to the geotechnical engineer, a foundation with small piles in the mineral subsoil would be the norm. The comparatively low impact on vegetation and soil, as well as the low degree of ground sealing, minimises conflicts with nature conservation and the target of a high groundwater recharge rate (9:97).

There are also numerous options and construction methods for the choice of modules and their orientation, which probably differ in impact, e.g., on shading and vegetation development. In addition to conventional ‘monofacial’ modules in a southern orientation, there are new technologies such as ‘bifacial’ modules in an east-west orientation or tube systems at a height of several metres (6:58).

3.2.8. SWOT Analysis of the Technological Dimension of Peatland PV

The SWOT matrix displays the main aspects of the technological dimension (

Table 3. SWOT matrix on Peatland PV in the technological dimension.

Strengths	Weaknesses
Adapted technology and equipment usable for different purposes in the project process	High degree of site and project specificity Changes in peat soil properties when wet (a) Reduced trafficability → Need for adapted equipment technology (b) Difficulties for installation → Deeper foundations, greater material costs and reduced manageability (c) Increased soil protection measures Additional technical effort and slowing down/extension of all project phases (soil investigations, access, installation, maintenance, dismantling, etc.) Soil investigations prior to rewetting only instructive to a limited extent for the situation after rewetting Need for adaptation of materials/constructions to acidic soil environment (corrosion protection) for comparable durability and service life Higher maintenance intensity (inspection, repair, cleaning, etc.) No empirical knowledge on the construction of Peatland PV
Opportunities	Threats
Technical innovation/solutions allow for Peatland PV in a state of full rewetting Negative impacts on vegetation and soil can be minimised through thorough project preparation Pilot projects with monitoring for knowledge gain and empirical values for future projects	Additional effort in planning and preparation, e.g., feasibility study Difficulty in planning and risk of unforeseen technical obstacles due to lack of experience Threat of negatively influencing the feasibility and profitability of a project

). The reference within the comparison is mostly open-space PV on mineral soils. From the technological perspective, there are hardly any strengths of Peatland PV but many weaknesses concerning planning, installation, operation, and dismantling, resulting in threats like additional expenditure, slowing down of the individual project phases, and questioning profitability. However, adapted technology and equipment are already available, and opportunities are created by improved technology, proper project planning, and knowledge gained from pilot sites.

3.3. Legal Dimension

In a constitutional state like Germany, every form of land use is subject to its legal framework which determines whether, where, in what form, and to what extent PV projects can be realised. New projects, procedures, and technologies can raise uncertainties regarding the application and interpretation of legal provisions, and it is not uncommon that amendments and adjustments are required by the legislator. The specialist lawyer for agricultural law emphasises the need for action not only in the adaptation but above all in the inter-coordination of the various specialised legal regulations, including spatial planning, construction legislation, the Renewable Energy Sources Act, and the nature conservation law (10:54).

3.3.1. Spatial Planning, Suitability Areas, and Construction Legislation

The German Spatial Planning Act (ROG) defines the tasks, guiding principles, and binding effects of spatial planning at the national level. Requirements are a cost-effective, secure, and environmentally compatible energy supply, as well as the expansion of energy networks. Further requirements, such as climate change mitigation, the expansion of renewable energies, and the preservation and development of natural sinks for substances harmful to the climate, must be considered (§ 2 para. 2 no. 4 ROG).

Since most of Germany is densely populated and its land is intensively used, land use is heavily regulated. These legal regulations should be adapted to allow for creative and synergetic land use solutions, according to the geotechnical engineer (9:109). PV should be constructed space-efficiently and close to the grid infrastructure if possible, and it is common ground among the experts that the potential for PV on conversion sites, brownfields, sealed sites, and roofs should be exploited first (2:62; 3:55; 6:60; 8:70; 10:71). In the meantime, the German government has also spoken out in favour of directing the PV expansion to roofs and other sealed surfaces, as well as to technologies that enable multiple uses of the surface [41]. Since the use of sealed surfaces for energy is expected to be not sufficient to achieve the climate targets by 2030 (2:62; 8:70), the potential of buildings and roof surfaces must be met with a similar amount of expansion in open space (2:62). In MV, the use of agricultural land for PV and therefore also Peatland PV is generally only allowed close to motorways, federal roads, and railways (LEP-LVO M-V). In 2021, the state parliament granted approval for the wider use of PV on agricultural land if certain criteria are met [42,43]. Various experts welcome the additional expansion of open-space PV, as well as the prospects of Peatland PV (2:62; 4:21; 10:71; 10:74).

In the designation process for open-space PV and Peatland PV, the exclusion principle could be applied. For example, protected areas, areas with a special value for the protection of species or the landscape should be excluded, according to the nature conservation expert (1:17). Instead, intensively used sites that are under strong ecological pressure should be considered as priority (5:12). Such sites could even benefit from enhancement through the implementation of Peatland PV (5:12; 5:15). The peatland expert refers to the strategy on peatland utilisation in MV and the proposed category ‘suitability without assessment requirements for paludiculture’, which comprises the most degraded peatland soils in MV with approximately 85,000 ha (8:57; 8:61) [8].

According to the experts, the bureaucracy surrounding the approval procedure for Peatland PV must be simplified, shortened, accelerated, and overall, designed more efficiently (1:57; 1:130; 4:69; 4:71; 5:133). The legal privileging of Peatland PV in the Building Code could help to speed up the necessary bureaucratic processes, comparable to the privileging of wind power in § 35 para. 1 BauGB (4:74; 10:60; 10:64; 10:67). Generally, all specialised legal regulations must be adapted and aligned in order to allow for efficient approval processes and the successful construction of Peatland PV plants in the end (10:56). Additionally, the designation of suitability areas could fasten the approval processes, either at the community level or at the federal spatial planning level (1:124; 1:130; 4:71; 10:61). Wind power, for example, is already covered by a specialised law, which mandates the individual states to define suitability areas and therefore fastens the approval processes.

The obligation of the municipality to inform and include a multitude of authorities and representatives of public interests is one reason for the complicated approval procedure, according to the agricultural law expert (10:56). The lower nature conservation authority usually has the most conflicts and thus often has the most objections (1:52). Therefore, the legislator should provide the nature conservation authority with guidelines for dealing with Peatland PV as soon as possible (8:66). The continuation of drainage-based agriculture with its negative climate impacts should be used as reference when authorities weigh up the opportunities and threats of Peatland PV (8:29). Concerns about negative developments comparable to the contradictory incentives of maize cultivation on drained peatlands for biogas production could be addressed by introducing an area cap per federal state (8:21). Experts were already considering the inclusion of peatland PV in the EEG in 2022 (5:133; 5:135), which has come into effect in the meantime [44].

3.3.2. Energy Legislation

In Germany, one of the most important legal frameworks for the realisation of open-space PV is the Renewable Energy Sources Act (EEG) and its amendments, although the EEG subsidy is generally becoming less important for open-space PV, as it competes with power purchase agreements (PPAs) (5:99). These PPAs are now running on a large scale (5:99). For Peatland PV, the EEG only has validity and increased attractiveness if a special allowance or a separate cost-efficient tender is introduced specifically for Peatland PV, according to a PV expert (5:99; 5:133; 5:135).

Due to additional costs, Peatland PV might have fewer chances in the EEG tender process compared with conventional open-space PV. Without a separate tendering segment, there is a risk that Peatland PV projects will not be selected. Policy adjustments were considered necessary by experts (2:49). Lack of knowledge about technical parameters makes it difficult to estimate the right amount of subsidies and fixed feed-in tariffs to ensure the economic operation of such Peatland PV constructions (4:84).

The amendment to the EEG 2023, which also mentions rewetting as a condition for the construction of open-space PV on peatlands, can be considered as the main turnout for Peatland PV (6:33). It is now a matter of law that the construction and operation of renewable energy plants are in the overriding public interest and serve public safety (§ 2 sentence 1 EEG 2023). In addition, Peatland PV is officially included as a new land category in the tenders for first-segment solar installations: According to § 37 para. 1 no. 3 lit. e EEG 2023, they belong to the special solar installations that meet the requirements laid down for them in a determination by the Federal Network Agency in accordance with § 85c EEG 2023, e) on drained and agriculturally used peatland soils, if the sites are permanently rewetted with the construction of the solar installation. The new regulation of the EEG 2023 requires bidders to declare that the construction of the plant will not create any additional obstacle to future rewetting of peatland soils (§ 30 para. 1 no. 9 EEG 2023). The applicable value for Peatland PV has increased by 0.5 cents/kWh, as per § 38b para. 1 sentence 3 EEG 2023. This value is used for calculating market premiums and feed-in tariffs. If the PV plant meets Federal Network Agency requirements [45], the applicable value is 7 cents/kWh. The additional agricultural use of the sites in the form of paludiculture (Paludi PV) can be regulated in the requirements (§ 85c para. 1 sentence 3 EEG 2023).

3.3.3. Nature Conservation Legislation

The agricultural representative is convinced that there are suitable sites in MV for the combination of peatland rewetting and open-space PV. Under the condition of a detailed assessment of compatibility with individual conservation objectives, they consider the categorical exclusion of protected areas inappropriate (2:40; 2:41; 2:46; 2:63). Another expert called for a political decision on which interest should be given greater weight in evaluation processes (3:36). The Federal Agency for Nature Conservation (BfN) and the German Nature and Biodiversity Conservation Union (NABU) agree that protected areas like the European Natura 2000 should be free of construction such as open-space PV. However, exceptions are possible for nature parks, landscape conservation areas, and biosphere reserve development zones, as long as the protection goals are met [46] (p. 6), [47].

Until electricity generation in Germany is GHG neutral, renewable energies are said to be prioritised in the respective balancing of conflicting interests (§ 2 sentence 2 EEG 2023). Even the expert from the conservation authority admits that in the course of the expansion of open-space PV and wind power, new standards would have to be set, and old taboos in conflict with nature conservation might have to be broken (1:130).

3.3.4. Land Status in Interim and Subsequent Use

In the approval process, the type of interim and subsequent land use should be specified in the development plan (10:27). Different classifications are possible, depending on the legal field, e.g., building planning law or agricultural subsidy law. Accordingly, a site that is no longer used for agricultural purposes due to the construction of an open-space PV plant loses its eligibility for subsidies of the EU Common Agricultural Policy (10:20).

According to § 9 para. 2 BauGB, land use and construction permits can be legally limited to a certain period of time or until certain circumstances arise. The subsequent use is to be specified in that case (§ 9 para. 2 BauGB). The legal framework § 201 BauGB only includes a definition of the term agriculture, but no further differentiation between arable land and grassland (10:27). Legal certainty regarding the subsequent use specifically as farmland is thus not given, according to the expert on agricultural law (10:27).

In addition to agricultural subsidy law, nature conservation law can protect permanent grassland (10:20), i.e., prohibiting the conversion to arable land if a grassland site was not ploughed for at least five years (DGErhG M-V). Whether extensive grassland developing below the PV modules is legally classified as permanent grassland or not is disputed among experts. According to the expert from the nature conservation authority, the interim use of PV plants is exempt from this regulation (1:177). This is opposed by the assessment of the energy agency expert and the expert for agricultural law (4:39; 10:32; 10:35). Both argue that the current legal framework does not guarantee a return to arable land after dismantling, as the building planning law cannot undermine nature conservation law and the Permanent Grassland Preservation Act. This controversy highlights the need for political clarification of legal framework conditions for interim and subsequent land status for conventional open-space PV, as well as Peatland PV and Paludi PV (4:39; 10:32; 10:35).

3.3.5. Consequences for Valuation and Inheritance Tax Legislation

Peatland PV is built on previously agriculturally used sites, which are tax-privileged property assets. The change in land use may affect the calculation of property tax and inheritance tax, causing economic hardship to landowners (10:41; 10:42). This is not limited to Peatland PV but affects open-space PV in general (10:48). Legislation must be adapted effectively to create legal certainty for landowners and farmers, e.g., regulations of the Valuation Law (BewG) and Inheritance Tax Law (ErbStG). Legal adjustments should be manageable, according to the experts (4:42; 10:45; 10:55).

3.3.6. Eco-Account Regulation and Guidelines on the Impact Mitigation Regulation

The German Building Code (BauGB) requires avoiding and compensating negative impacts on the landscape and balance of nature. Interventions in nature and landscape involve changes to the shape or use of land or to the groundwater level that may significantly impair the balance of nature or landscape’s performance (BNatSchG). State law specifies what is considered an intervention (NatSchAG M-V) and regulates compensation measures and their stocking for future interventions through eco-accounts and land agency recognition (ÖkoKtoVO M-V). Compensation needs and requirements are detailed in the Guidelines on the Impact Mitigation Regulation (HzE).

The implementation of the Impact Mitigation Regulation differs in the federal states, with so-called eco-points being calculated for the change in value of initial and target biotopes (3:45). In MV, the compensation measures themselves are assessed in proportion to the size of the area (3:45). Generally, measures such as rewetting are only granted if permanence can be ensured (3:49). Maintaining the carbon store as an ecosystem service does not yet play a role in the impact compensation regulation (3:45). However, the threat of missed target conditions, such as specific water levels, could cause additional problems (3:82). The inclusion of securing the carbon store as an ecosystem service in the Eco-Account Regulation and further guidelines (HzE) is generally possible (3:78). This concerns the preservation of the existing carbon store and minimising CO₂ emissions. Carbon storage as a process, i.e., carbon sequestration, has to be assessed differently. According to an expert, the increase in carbon accumulation on the site is questionable (6:54).

The construction of an open-space PV plant with simultaneous compensation by rewetting peatland on the same site has not been implemented yet and is not included in the Guidelines on the Impact Mitigation Regulation (HzE). Due to ecological restrictions, e.g., for breeding and resting birds, it would certainly not be possible to achieve the same ecosystem value as with pure rewetting. If rewetting is counted as a compensation measure, a change in the HzE specifications is required (3:32; 3:45). One expert argues that rewetting should be sufficient as compensation for the impact of the Peatland PV plant (7:125; 7:132; 7:135).

3.3.7. SWOT Analysis on the Legal Dimension of Peatland PV

Table 4. SWOT matrix on Peatland PV in the legal dimension.

Strengths	Weaknesses
Integration of Peatland PV in the Renewable Energy Sources Act (§ 37 para. 1 no. 3 e EEG 2023) Construction and operation of plants to produce renewable energies are in the public interest and serve public security (according to the amendments in § 2 EEG 2023)	Uncertainties for applicants of PV plants due to slow, complicated approval processes/bureaucracy Uncertainties for authorities in dealing with the approval of Peatland PV due to lack of administrative regulations Uncertainties on interim and subsequent use Uncertainties in the Valuation Law and Inheritance Tax Law → Official conversion leads to very high inheritance tax amounts Uncertainties regarding Impact Mitigation Regulation → No guidelines for dealing with Peatland PV, e.g., intervention and compensation on the same site
Opportunities	Threats
Designation of suitability areas Flexibilisation of land use planning law Adaptation of spatial planning law, building law, agricultural subsidy law, Valuation and Inheritance Tax Law and the Impact Mitigation Regulation, as well as coordination of the entire specialised legal regulations with each other	Obstacles due to the complexity of different specialised legal regulations and lack of coordination Threats for the realisation of Peatland PV, especially for pioneers until adaptation and alignment of specialised legal regulations

highlights the SWOT aspects of the legal dimension, with the amendment to the EEG 2023 explicitly mentioning Peatland PV and declaring that renewable energies are in the public interest as a strength. However, multiple weaknesses in the legal dimension are evident due to ambiguities in specialised legal regulations. Adaptations offer opportunities for legally secure implementation. The difficulty of harmonising complex regulations is a threat. Multiple legal uncertainties are considered as weaknesses causing threats in the practical realisation of Peatland PV, especially for pioneers.

3.4. Economic Dimension

The economic dimension of Peatland PV is complex and interconnected with other dimensions. It involves the business perspective of landowners, land users, and PV project developers, as well as the macroeconomic and societal perspective, including social acceptance. Profitability is crucial, as measures that do not yield profits are unlikely to be implemented (4:54).

3.4.1. Economic Profitability for the PV Project Developer

Experts see great threats to the economic viability of Peatland PV, especially due to the technical hurdles and the resulting additional time and financial effort (2:49; 5:45; 5:106; 7:75; 7:166; 10:42). The additional technical effort, which is mainly due to higher material costs, more specialised equipment, and more challenging operations, is highly dependent on the individual project (5:45). Some experts estimate the additional costs for the overall installation at 10 to 20% (7:75; 9:60), while one expert could even imagine an increase of 50 to 100% (5:48). Depending on the financial leeway due to other framework conditions, these additional costs can also bring down a project (5:45).

The rewetting itself costs a lot of time and money and it should be considered financially separate from the construction of the Peatland PV (1:142; 5:107; 8:50; 8:52). Restoration measures are funded by the federal state and the EU (1:143). Peatland PV as land use after rewetting could create added value (8:52).

The operating times are usually 20 to 25 years for conventional open-space PV modules, but investors tend more towards 30 to 35 years, also depending on the location, according to a PV expert (5:116). Roughly speaking, it can take about five to ten years until amortisation (5:119).

The durability of the materials through sufficient corrosion protection is one of the most important critical factors for the economic feasibility of Peatland PV (9:73). Reliable and sufficient experience with chemical resistance already exists, so that service lives of 30 years, which are customary for banks, can be realised (9:76). This is important to ensure that the constructions can be used in accordance with the financing and thus to ensure economic viability. However, one expert feared that due to the many technical uncertainties, hardly any bank would be willing to finance Peatland PV as things were at the time of the interview (March 2022) (4:65).

One PV expert is critical here: They roughly estimate the additional costs for Peatland PV at 10 to 20% of the total installation. In their opinion, the conventional profit margin is not sufficient to compensate for this (7:72; 7:75). Due to the additional costs for the technical implementation of Peatland PV, the expert has strong doubts about the profitability of Peatland PV and sees the need for further incentives for the implementation of Peatland PV (7:162).

The first subsidies for Peatland PV were introduced with the Renewable Energy Sources Act 2023. Previously (at the time of the interviews), various experts had already mentioned such feed-in tariff subsidies as an incentive tool (1:21; 2:49; 4:109; 7:72; 7:169). In addition to a sufficient feed-in tariff, there are other factors relevant to the project realisation. The availability of suitable and sufficiently large sites also plays a role in the competitiveness of Peatland PV (5:58; 5:71).

In addition, the individual projects would have to cover a sufficiently large and relatively similarly structured site (5:58). For sufficient project profitability, the minimum size of an open-space PV plant is 5 to 6 ha or 5 MWp (5:68; 5:100) [48] (p. 23). The electricity price also depends on the size of the project (5:99). Since smaller projects are unprofitable, it would be better to aim for pure rewetting of such small peatland sites instead (5:68). Increased space requirements of adapted machines and increased row spacing could pose a threat to the necessary economies of scale of Peatland PV projects (7:48).

3.4.2. Economic Profitability for the Landowner and User

Given the scarcity of land due to conflicts between a multitude of different land use interests, an innovative land use form or combination must also be economically viable and competitive. Since most peatland is currently used by drainage-based agriculture, farmers and landowners are relevant actors. According to the farmers’ representatives, the share of rented land is relatively high in MV: 60 to 70% of agricultural production takes place on rented land and only 30 to 40% on land owned by the farmers (2:22).

Possible rental income for the owner of agricultural land or the profit that a farmer can make strongly depends on the respective agricultural usage (7:57). According to the experts, landowners in MV can receive on average 200 to 300 EUR/ha rental payments if they rent out agricultural land (7:57), while farmers make profits from cultivating the land between 300 and 1000 EUR/ha with an average of about 600 EUR/ha (4:57; 4:85; 7:57). Landowners, as well as farmers, could receive much higher income by renting out their land for open-space PV, without farmers having to regularly cultivate the fields themselves (4:85). The rental payments for open-space PV range from 2000 to 4000 EUR/ha/a (2:25; 4:92; 7:55), strongly depending on the respective region, and with exceptions of less than 1000 EUR/ha/a (7:51). While rents for open-space PV in other federal states reached higher prices, in MV they would be 1500 to 2000 EUR/ha/a (7:55). In contrast, rental payments for agricultural use in MV were on average 323 EUR/ha for arable land and 178 EUR/ha for grassland in 2023 [49]. At current electricity prices, open-space PV pays off for everyone (4:101). Ultimately, a farmer with conventional biomass production cannot compete with these revenues from open-space PV (1:21; 2:25). From the perspective of a PV project developer, the agricultural production value or soil fertility are not decisive, as long as the sites are PV-compatible (4:98).

Giving up or stopping the utilisation of sites without payment or compensation, for example, due to peatland rewetting, is not an option for landowners from a purely economic point of view (4:57). So far, rewetting of mostly privately owned peatlands has always been dependent on the willingness of landowners, and thus, just very few peatland restoration projects have been realised (1:137; 8:30). In contrast to agricultural land use and open-space PV, there is currently no revenue to be made from pure peatland protection through rewetting (1:20).

The implementation of such projects is almost always linked to compensation claims, which amount to 2000 to 3000 EUR/ha/a, according to the conservation expert (1:144). Considering the necessary scope of rewetting, long-term funding is unclear (1:137). An alternative to compensation payments is land swapping, according to the conservation expert (1:82; 1:88). However, livestock farms, in particular, depend on the sites for fodder production in agricultural use and are therefore not very interested in compensation payments (1:82). In addition, the Ministry of Finance MV’s mandate to the land administration is to maintain the value of the state’s land and to preserve the rental income (3:42). Land swaps only shift the question of compensation (3:42).

The lawyer for agricultural law concludes that economic aspects and the protection of one’s own capital are ultimately the decisive factors for farms and landowners (10:79). If these peatlands have to be withdrawn from agricultural use in the interest of climate change mitigation (10:12), then they can at least be put to other beneficial uses through the construction of Peatland PV, which can also create synergy effects (10:16). Incentives, possibly through attractive subsidies, should be created to convince landowners (10:17).

The question of to what extent one is prepared to economise nature conservation is raised by the conservation expert (1:28). For the implementation of peatland protection on a large scale across the board, a certain economic added value must ultimately be generated (1:113). Thus, should Peatland PV generate greater income than conventional grassland use, this could certainly provide an incentive for peatland conservation on sites previously destroyed by drainage (1:21; 1:135; 3:65). It is unrealistic to simply leave several hundred thousand hectares to themselves throughout Germany (3:65). In this context, Peatland PV can be considered as a viable option (3:65), next to paludiculture (6:28).

The potential uses of one and the same rewetted peatland site could even be extended beyond Peatland PV (8:75). For example, the renewable energy production of Peatland PV could be combined with the energetic utilisation of growths from rewetted peatlands. This combination of renewable energy, agricultural biomass production, and the rewetting of peatlands, called Paludi PV (8:75), is illustrated in Figure 1.

Stakeholders, such as farmers, always need to be included at an early stage (2:103). Especially for farms that provide or need fodder, perspectives must be created, and amicable solutions must be found (2:18; 2:37; 2:103). It cannot be predicted whether Peatland PV will provide incentives for rewetting as long as certain framework conditions are not clarified (4:8; 4:10), but in the case of economic profitability of Peatland PV, a corresponding leverage potential is possible (6:29).

3.4.3. Subsidies and Incentives Affect Land Use Decisions

The economic feasibility of Peatland PV is influenced by the opportunity costs, i.e. the income forgone of the best alternative land uses, and related positive or negative incentives. Several interviewees stressed the effect of existing agricultural subsidies for drained peatlands on the one hand (1:201; 3:72; 3:75; 6:47; 6:76) and of a possible introduction of CO₂ pricing for the land use sector in the future (4:57; 4:60). The expert from the agricultural ministry considers a political change regarding agricultural subsidies and emissions trading as inevitable, especially in the light of the national goal of GHG neutrality by 2045 (6:47; 6:51; 6:76; 6:79). In order to achieve the climate change mitigation goals and to make climate-friendly forms of land use such as Peatland PV more marketable, the eligibility of drainage-based land use on peatland for agricultural subsidies must be discontinued as a first step (3:72; 6:47; 6:51). Here, the fact that peatland protection is in the public interest must be considered (3:64). Especially the subsidy approach is criticised: if a subsidy for Peatland PV is introduced but at the same time agricultural payments for drainage-based agriculture are paid, this subsidy must be scaled higher than the agricultural payment (6:76). This is contradictory, inefficient, and expensive (6:76).

Next to phasing out subsidies for drainage, the inclusion of peatland emissions in an emissions trading system has been discussed. So far, carbon credits are traded only on the voluntary market (4:57). The lawyer is confident that emissions from the land use sector will also be included in the European Emissions Trading Scheme and that this industry will be treated more and more like other industries in the future (10:82). Some experts have doubts about the successful implementation of a CO₂ pricing instrument that actually corresponds to an extensive internalisation of external costs (4:60), especially against the background of further strong agricultural lobby groups at federal and EU level (6:51). Furthermore, the pricing of CO₂ emissions from land use requires an effective instrument for quantifying emissions (3:78; 3:81). The generation and sale of carbon credits in combination with Peatland PV could be a profitable deal for landowners. Certainly, pricing the emissions of a land use that has been practised for decades represents a considerable encroachment on property, but the need for this pricing cannot be dismissed, according to the lawyer, and the fact that something has been done in a certain way for decades is not the strongest argument (10:85).

3.4.4. Social Acceptance of Land Use Transformation

When reflecting on economic issues, experts also raise concerns about social acceptance. It is considered crucial for both rewetting and renewable energy expansion. Most people are not aware of the climate relevance of peatlands, and the discourse on their importance is not conducted accordingly (6:73). The rewetting of drained peatland sites is desirable, but abandoning the use of 1.8 million hectares of peatland in Germany is naive, according to the peatland expert (8:71). Wherever compatible with conservation goals, Peatland PV or Paludi PV can reduce the land use pressure of the renewable energy production on mineral soils (8:75). Good mineral arable soils are essential for food security and should be primarily used for agriculture (2:40; 2:63; 8:75).

According to one expert, the difference between conventional open-space PV and Peatland PV will likely have little influence on social acceptance, as people prefer to preserve cultural landscapes (4:78; 4:81). Moreover, acceptance of building over large areas with open-space PV is considered low, and not only because MV is already producing renewable energy in the range of 180 to 190% of its electricity demand (4:75). Proper communication is crucial in promoting renewable energies, even if the gradual expansion is easier to communicate than sudden massive increases (4:75).

When aiming to meet climate change mitigation goals, it is necessary to double or triple PV installations by 2030 (2:62). The PV experts approve Peatland PV’s potential to reactivate sites and expand the land potential for the PV expansion while additionally contributing to climate change mitigation (5:19; 9:20). The expert of the energy agency predicts the threat of nature conservation objections to be high but is confident in landowner acceptance and potential leverage effect (6:73).

3.4.5. SWOT Analysis on the Economic Dimension of Peatland PV

The economic dimension of Peatland PV encompasses both business and economic aspects (

Table 5. SWOT matrix on Peatland PV in the economic dimension.

Strengths	Weaknesses
Further utilisation and land rental opportunities for landowners with (a) guaranteed income from feed-in tariffs and (b) significantly higher rental income Inclusion in the EEG 2023 as a separate land category Expansion of land potential for PV through greater availability of land Expansion of renewable energies and substitution of fossil energies	Higher costs due to technological difficulties, i.e., additional costs (a) for construction (especially for substructure/foundation) (b) due to increased effort for maintenance, care, mowing, cleaning (c) due to the provision of appropriate technology/equipment for construction work (d) due to increased soil protection measures Little chance of competing in normal tendering procedures (addressed by the amendment to the EEG 2023) Impairments for local residents and infrastructure due to rewetting Loss of agricultural biomass production
Opportunities	Threats
Incentive/leverage for larger rewetting projects Contribution to combating climate change/ the climate crisis and thus mitigating negative consequences for society as a whole Contribution to energy self-sufficiency and energy security (especially since the start of Russia’s war of aggression on Ukraine) Mitigation of opportunity costs and conflicting incentives in the land use sector Valorisation of ecosystem services, i.e., internalisation of external costs and benefits, e.g., through the introduction of emissions trading	Total additional costs for a Peatland PV project difficult to estimate due to technological challenges Compensation payments to those affected by rewetting Risk of lack of profitability of the whole project Risk of unwillingness of banks to finance Peatland PV projects Reluctance to take on the role of a pioneer due to lack of experience Lack of opportunities for people affected to exert influence on political processes Uncertainty regarding social acceptance in society, among landowners and land managers

). The main economic strength of Peatland PV is the continued value creation in a rewetted state, which creates opportunities for secured income from feed-in or increased rental income of landowners. The additional costs that result primarily from the technical difficulties pose a threat to the necessary bank financing and overall profitability of the project. Peatland PV as a separate land category with increased feed-in tariffs presents an opportunity to expand renewable energy supply and contribute to energy self-sufficiency, especially during times of energy crises. Landowners face legal uncertainties and economic threats, e.g., concerning inheritance tax and land value maintenance.

3.5. Assessment of the Future Prospects of Peatland PV

3.5.1. The Need for Pilot Projects to Gain Practical Knowledge

Against the background of numerous crises and new challenges, especially in the field of land use and energy production, almost all experts call for the establishment and promotion of pilot projects for Peatland PV (1:16; 7:166; 8:78). Finally, there is a lack of practical experience regarding the implementation of open-space PV in connection with the rewetting of peatland areas (1:46; 1:103; 3:28). The open questions regarding implementation of Peatland PV are numerous (3:48).

Such pilot projects should be comprehensively monitored in terms of flora and fauna (1:138). The gained experience could be used to optimise the construction of the PV plant in terms of row spacing, size, and angle of the modules (1:138). In addition to testing the installation of the foundation in a wet peatland, long-term tests regarding the durability of the materials and their service life are relevant (7:108). Technical conditions and their impact on profitability can only be assessed in detail when considering a specific project (5:48).

3.5.2. Overall Assessment of the Opportunities and Threats of Peatland PV

At the end of each interview, all experts were asked for their final overall assessment of the opportunities and threats for Peatland PV (Figure 2). For one expert, who opted for a scale value of 2, the threats outweighed the opportunities. Nine out of ten experts rated the opportunities as predominant (values of 6 to 9). The average scale value is 6.6. While the two PV experts were either very sceptical (value 2) or indecisive on the potential of Peatland PV (value 6), the geotechnical engineer was very confident the opportunities predominate (value 8).

3.5.3. TOWS Analysis and Recommendations for the Implementation of Peatland PV

The TOWS matrix relates the main previously identified strengths, weaknesses, opportunities, and threats to each other and helps to derive recommendations for the implementation of Peatland PV (

Table 6. TOWS matrix with recommendations for the implementation of Peatland PV.

	Strengths	Weaknesses
	Restoration of the ecosystem services of peatlands through rewetting Adapted technology and equipment usable for different purposes Integration of Peatland PV in the EEG 2023 Further utilisation of rewetted land and land rental opportunities for landowners Renewable energy production	Possible negative impacts on conservation objectives Additional technical effort and slowing down/extension of all project phases Uncertainties for applicants of PV plants due to slow, complicated approval processes/bureaucracy Higher costs due to technological and approval difficulties
Opportunities	SO: Leverage strengths to benefit from opportunities	WO: Overcome weaknesses by seizing opportunities
Reduction in GHG emissions in the land use sector Technical innovation/solutions allow for Peatland PV in a state of full rewetting Adaptation of relevant laws and improved coordination of specialised legal regulations Valorisation of ecosystem services, i.e., internalisation of external costs and benefits Mitigation of land use pressure through combined land use Substitution of fossil energy sources	Promote the combined land use and use the twofold reduction in CO2 emissions through rewetting and renewable energy production to reduce conflicts and achieve societal objectives Use the best available technologies and establish Peatland PV under full rewetting conditions to reduce the GHG emissions of the land use sector Make full use of the EEG and enhance renewable energies to substitute fossil energy sources and contribute to energy self-sufficiency and energy security	Reduce negative environmental impacts, technical efforts and costs by improving technologies Resolve inconsistencies, speed up processes and reduce bureaucratic costs and uncertainties by adapting and aligning relevant laws and specialised legal regulations Cover higher costs by using payments for ecosystem services
Threats	ST: Use strengths to protect against threats	WT: Overcome weaknessesby minimising threats
Conflicts with nature conservation due to unknown influence on flora and fauna Difficulty in planning and risk of unforeseen technical obstacles due to lack of experience Difficulty of harmonising complex specialised legal regulations Uncertainty regarding the profitability of Peatland PV compared with other open-space PV projects Uncertainty regarding social acceptance	Identify co-benefits of Peatland PV with conservation objectives to turn conflicts into synergies Use adapted technologies to minimise conflicts with nature conservation Make use of the feed-in market premium offered by the EEG to reduce uncertainty regarding profitability Use continued added value to enhance social acceptance	Reduce uncertainties regarding the interplay with flora and fauna, peat soil and carbon store by establishing pilot projects with monitoring and scientific support Establish and secure profitability by reducing technical hurdles and gaining experience in pilot projects Reduce uncertainties of approval processes by including Peatland PV in harmonised specialised legal regulations Strengthen the marketability of Peatland PV by removing false incentives, such as subsidies for land uses harmful to the climate

). The strengths and opportunities primarily relate to an economic benefit in the area of climate change mitigation. The elimination of technical and legal weaknesses and hurdles can help to increase the profitability and thus the attractiveness of the practical implementation of Peatland PV. To create more economic incentives, possibilities for internalizing external costs of peatland drainage and external benefits of rewetting should be examined. Acceptance among stakeholders and society can also be increased by addressing conflicting objectives and opportunity costs in land use. Possible threats to flora, fauna, and soil should be further researched as part of pilot projects.

4. Discussion

4.1. Contribution and Transferability of This Study

Phasing out peatland drainage is a complex exnovation problem, and Peatland PV is considered as one possible innovation pathway to support acceptance for this sociotechnical transition [50]. In a dynamic phase of social and political discourse, this article provides a first, multidimensional insight into possible strengths and weaknesses, opportunities, and threats of Peatland PV. This innovative land use combination was examined concerning the ecological and technological, but above all with a focus on the economic-legal framework conditions. While most interviewees of this study considered the opportunities of Peatland PV to be predominant, weaknesses and threats have been identified in all the dimensions.

Although this study was conducted with a regional focus on North-East Germany, its results are relevant for other regions in Germany, other countries in the European Union (EU), and beyond. The production of solar (or wind) power on peatlands is also discussed in other peatland-rich countries, e.g., the United Kingdom, Ireland, Finland, the Netherlands, Poland, Latvia, and Indonesia, among others [7,17,18,51]. The limits of transferability of the results to other regions or countries are to be determined individually in the respective context. Ecological and technical aspects must always be considered in view of site- and project-specific conditions. Drained peatlands in MV are, for instance, mainly fens, while bogs dominate in North-West Germany [52]. The types of peatland, which show a large diversity in Germany, Europe [53], and worldwide [54], may significantly affect the ecological and technological dimensions of Peatland PV. As for the economic dimension, it should be remembered that MV is sparsely populated, and large-scale farming and low livestock densities characterise agriculture [55]. Differences in agricultural structures but also population densities among countries and regions are likely to affect the economic dimension of Peatland PV and its adaptation, as has been observed in the case of agrivoltaics [56]. Finally, the assessment of the legal framework has a spatial focus on MV, as one of the federal states of Germany, and as Germany is one of the Member States of the EU. Although the federal laws and regulations need to comply with the laws and regulations of the EU and apply to the whole of Germany, it should be noted that the individual states in Germany enjoy a certain degree of freedom in implementing federal laws and enacting state-specific laws. There is evidence that legislative acts have major impacts on the development of renewable energies [57].

Although the results of the specific laws and regulations may lack transferability beyond Germany, they represent the major legal and policy areas that likely need to be considered also in other countries, such as spatial planning and construction, nature conservation, climate change mitigation, and (renewable) energy. For instance, all Member States of the EU are obliged to ensure that until climate neutrality is reached, the ‘permit-granting procedure, the planning, construction and operation of renewable energy plants, the connection of such plants to the grid, the related grid itself, and storage assets are presumed as being in the overriding public interest’ (Directive (EU) 2023/2413) [58] (p. 41). Member States should also accelerate the permit-granting procedure and define renewable acceleration areas, and they are allowed to exclude solar power from certain areas. The newly enacted nature restoration law (Regulation (EU) 2024/1991) requires Member States to rewet peatlands but also states that ‘the restoration of biodiversity should take into account the deployment of renewable energy and vice versa. It should be possible to combine restoration activities and the deployment of renewable energy projects, wherever possible…’ [59] (p. 13). Peatland PV outside protected areas would exactly do that. Overall, this explorative study can contribute to the field development of a highly topical issue, inspire future studies, and support the derivation of general strategies for the future implementation of Peatland PV.

4.2. Lack of Implementation and Missing Stakeholder Perspectives

To the best of our knowledge, this study is the first to reflect in detail on implementing open-space PV in combination with the intended rewetting of peatlands. In Germany, two specific PV plants on peat soils are mentioned in relation to raised water levels, but full rewetting was either not intended or not achieved: In Lottorf (Schleswig-Holstein), the drainage system was partially destroyed during the construction of the PV plant; in Schornhof (Bavaria), the approval of the hydrological report was still pending two years after installation [14].

Due to the lack of scientific literature, this study is mainly reliant on expert interviews. Since no Peatland PV plants have been implemented in Germany to date, the experts’ statements are not based on verified empirical experience. Instead, the assessments are based on their individual field of expertise. The interviews revealed a consensus among the different experts that Peatland PV contributes to climate change mitigation, both by raising water levels and renewable energy production, but divergent knowledge on required target water levels and related ecosystem functions. Some experts shared a common misunderstanding, which assumes that peatlands are rewetted for carbon sequestration, becoming a new carbon sink, while the major effect of restoring the carbon store function is actually a reduction in GHG emissions by preserving the existing carbon stock.

With the selection of the 10 experts for interviews, not all possible stakeholder perspectives on Peatland PV could be fully covered, e.g., those of landowners, municipalities, etc. The reluctance to be interviewed by some experts with a particularly negative attitude towards the implementation of Peatland PV may also have led to a bias in the average overall assessment. However, these reservations might be directed not only against Peatland PV in particular but against the use of open spaces for renewable energy production in general [60]. The implementation of pilot projects will increase knowledge and may alter the assessments in all dimensions.

4.3. Limitations of the SWOT Method

This study applies the SWOT analysis not to a company in its market environment but to an innovative combination of land uses. Some weaknesses of the SWOT method have been identified in previous studies, including the distinction between internal and external factors and the hard delineation of the considered time horizon [33] (p. 67). Transferring the SWOT method to the context of an innovative form of land use revealed further difficulties. In this case, the various SWOT aspects have two basic directions of impact: (1) SWOT aspects ‘of’ Peatland PV with an impact from inside outwards and (2) SWOT aspects with an impact ‘on’ Peatland PV from outside inwards. However, the direction of impact could not be clearly and exclusively identified for each aspect nor differentiated in the SWOT matrices (Table 2, Table 3, Table 4 and Table 5).

4.4. Increasing Transparency in the Discussion: What Is the Reference System?

Due to the different professional backgrounds and interests of the experts, they also take different perspectives on Peatland PV and emphasise different aspects. Generalisation and extrapolation always mean a shortening of reality. A general tendency can be identified, however, concerning the respective areas of application and of reference: Peatland climate experts mostly apply the reference system from Figure 3a and compare land uses with and without peatland rewetting. Conservationists often express concerns within the reference system Figure 3b and compare Peatland PV land use with pure rewetting. PV experts often refer to the similarities of Peatland PV with conventional open-space PV (Figure 3c) and to their differences (Figure 3d). Agricultural representatives emphasise the need to preserve sites for agricultural biomass production and use this as a benchmark for their consideration (Figure 3e). Innovative land use combinations are often discussed controversially in public discourse. Their area of application is visualised in Figure 3f. A lawyer, on the other hand, must ultimately consider all legally relevant aspects, the area of application of which must be determined individually for different land uses.

This study reveals the diversity of the reference systems on which experts base their assessments and opinions. Once Peatland PV has progressed further into science, politics, and society, a discourse analysis on the topic could provide interesting insights.

4.5. Contribution to the Energy Transition: Spatial Relevance of Peatland PV

The results of this study demonstrate that Peatland PV should not be understood in competition with but, like all other open-space and agrivoltaics, rather as a complement to expanding PV on conversion areas, buildings, and sealed surfaces. The Fraunhofer Institute for Solar Energy Systems emphasises the urgency of the energy transition, stating that there is no time to trial options sequentially; instead, the focus should be on parallel expansion, including building-integrated PV, urban areas, transport routes and vehicles, agrivoltaics, and floating PV [61] (p. 31). To achieve GHG reductions in Germany, renewable energies must expand by 60% by 2030 and by 100% by 2045, with an annual increase of 19 to 23 GW per year from 2021 to 2045 [62] (p. 3). The technical potential for Peatland PV is estimated at 270 to 660 GWp, based on the agriculturally used peatland area of 1.1 million hectares and an occupancy density of 0.25 to 0.6 MWp/ha [61] (p. 36). When considering the possible PV potential in Germany, a distinction needs to be made between theoretical, technical, and economic–practical potential [61] (pp. 31 f.). Complex economic, legal, and technological framework conditions, as well as social acceptance, determine which portion of the technical potential can be utilised practically and commercially [61] (p. 34). Recently, it was estimated that if socioeconomic, technological, and environmental constraints are taken into account, the potential of Peatland PV is reduced to 0.1 or 0.2 million hectares suitable for large-scale PV plants (>10 ha) [15].

4.6. Strategies for Implementing Peatland PV

Based on the study results, key recommendations for the implementation of Peatland PV can be derived to overcome current weaknesses and protect against possible threats, especially in the ecological, technological, and legal dimensions.

➢

Great need for pilot sites with accompanying research

Most of the experts call for pilot sites (Section 3.5) to verify the expected improvement in hydrology and carbon storage, monitor flora and fauna, and gain knowledge on technical implementation (e.g., construction design, module sizes, orientation, inclination, row spacing), as well as the different impacts on shading, vegetation cover, and evapotranspiration. Socio-economic research addressing the profitability for different stakeholders (Section 3.4) under different business and contracting models, as well as social acceptance (Section 3.4), should always accompany the pilot sites.

➢

Consider the introduction of a temporary regional area cap

Concerns about the negative impacts of Peatland PV and the threat of unwanted developments could be addressed by introducing an area cap per federal state (Section 3.3), thus allowing for pilot projects and knowledge generation in a first step, which can provide evidence-based guidelines for possible larger-scale implementation in a second step [14].

➢

Ensure complete rewetting for subsidized Peatland PV

Water levels close to the surface are the prerequisite for peat-preserving conditions in Peatland PV [14] (pp. 2–3). According to expert information presented in this study, solutions exist for all technical hurdles, even for full rewetting (Section 3.2). The Federal Network Agency requires minimum water levels of 10 cm below the surface in winter and 30 cm below the surface in summer [45] (No. 2 d)). These summer water levels are still peat-depleting and should be complemented by the requirement of an average water level of 10 cm below the surface (or higher) during summer (April to September) to ensure peat preservation [63] (pp. 3–4). Minimum water levels need to be maintained in the peat body; however, ditch water levels are no sufficient indicators [63] (p. 3). The targeted minimum water levels must be confirmed by the water authority or proven by submitting a hydrological report to the grid operator [45] (No. 2 f)).

➢

Prevent PV construction on peat soils without rewetting

According to the expert information, open-space PV is installed already on more than 500 ha of drained peat soils (Section 3.1.2). The Federal Network Agency’s requirements for Peatland PV under § 85c EEG 2023 only apply to the eligibility for subsidies under the EEG but not beyond. Thus, the steering function of the EEG is limited. The construction of conventional open-space PV on drained peatlands without rewetting measures continues due to the profitability of PPAs outside the EEG. To effectively prevent open-space PV on drained peatlands, further legal provisions must be adopted, also in Germany.

➢

Provide guidelines for dealing with conflicts of interest during the approval processes

The uncertainty connected to the approval of a Peatland PV project was identified as a major weakness both for applicants and for the authorities (Section 3.3). Possible conflicts with species protection and with other legally protected goods like water, soil, and climate require a complex weighing of interests. Similar obstacles are known for the rewetting of peatlands itself since rewetting is not necessarily compatible with the objectives of nature conservation or the water framework directive [64] (p. 16). Planning and approval procedures of peatland rewetting projects are time-consuming and costly, especially due to difficult case-by-case assessments typically arising from a lack of clear regulations on how to deal with conflicting objectives and a lack of prioritisation [65] (p. 8). PV installations might alleviate the situation further. To accelerate peatland rewetting with and without PV, regulatory changes to, e.g., water, soil, and conservation law, as well as guidelines for approval authorities on balancing conflicting interests are recommended. For instance, when assessing a trade-off between existing and new species on the site, a distinction between species that are typical and atypical for wet peatland sites is necessary. Furthermore, the implementation of Peatland PV can be facilitated if the compensation obligations according to the Impact Mitigation Regulation can be fulfilled on the same site by raising the water levels to the surface.

➢

Consider the introduction of suitability areas

Some experts suggested the designation of suitability areas for Peatland PV (Section 3.3). Identifying areas with low conflict potential may be an approach to accelerate approval procedures [16]. Identifying the most degraded peat soils as suitable areas for cropping paludiculture in North-East Germany (85,500 ha in MV, Section 3.3.1), as well as the deliberative process involving different authorities and stakeholders, may serve as a blueprint [14] (p. 3), [66] (p. 66).

➢

Designate renewable energies and peatland rewetting to be of overriding public interest

According to § 2 EEG 2023, state authorities must consider renewable energies in the overriding public interest (Section 3.3.2). This prioritisation of renewable energies can have a strong influence on administrative decisions [67] (p. 4). When weighing renewable energies against other legal interests, like nature conservation and building law, renewable energies should only be overcome in exceptional cases. This assessment is founded in constitutional law [68] (para. 111 ff.) [69] (para. 159 f.) [70] (para. 73; 85) [71,72]. The legal possibilities created by § 2 EEG 2023 might also support the implementation of pilot projects of Peatland PV. Legally enshrining peatland climate change mitigation as an (overriding) public interest in various laws is also suggested to accelerate and upscale peatland rewetting in Germany in general [64] and could additionally support Peatland PV.

➢

Create legal certainty

The adaptation of the legal framework (Section 3.3) is important to leverage the opportunities of Peatland PV, accelerate procedures, and reduce bureaucracy. On the other hand, legal regulations can guide the expansion and minimise possible threats. Following the inclusion of Peatland PV as a separate land category in the Renewable Energy Sources Act 2023, various legal problems remain: The challenge for the legislator will be to coordinate and harmonise all relevant specialised legal regulations — starting with spatial planning, building, agricultural subsidy, and nature conservation law. Regarding the Valuation Law and Inheritance Tax Law, similar clarity on the application must be created as has already been carried out for agrivoltaics. In addition, legal clarity must be provided, particularly concerning the land status, including the possibility for agricultural use in interim and subsequent use, to reduce uncertainties for stakeholders, especially landowners.

4.7. Can Peatland PV Become Economically Feasible?

The additional time and financial expenditure in all project steps, from planning and installation to maintenance, care, mowing, and dismantling, have a significant influence on the profitability of Peatland PV. The economic profitability and resulting marketability ultimately remain two of the most critical factors in the implementation of Peatland PV. However, if those can be achieved, Peatland PV might stop the decline in land value by offering an alternative source of income for landowners and setting incentives for rewetting [73]. For an assumed plant size of 10 MWp (11 ha) in Schleswig-Holstein/ North-West Germany, the profitability of Peatland PV was estimated and compared with open-space PV on mineral soil [68]. They concluded that the possible rental payments would be in general lower for Peatland PV compared with the alternative but still positive and competitive with agriculture if the feed-in point is within a range of 6 to 7 km from the plant. A distance of 3 km would allow the investor a rental payment of 2200 EUR/ha, thus exceeding the average contribution margin of intensive dairy farming [74] (p. 56). In this study, Peatland PV was calculated with increased revenues of 0.5 cents/kWh under the EEG 2023 and additional investment and maintenance costs of 12.7% and 3%, respectively [74] (p. 51). The calculated additional costs did not include the costs of rewetting.

Adapting the policy and regulatory framework can make Peatland PV a more attractive land use alternative in the future. Phasing out false incentives like agricultural subsidies for drainage-based agriculture, as well as agri-environmental payments that do not require water level elevations, would reduce opportunity costs, especially in the case of low-intensity peatland use. Other governance instruments that are suitable to account for the role of peatlands as long-term carbon stores in a wet state or as a disproportionately high source of GHG emissions in a drained state are, for instance, a CO₂ tax or CO₂ certificates. The EU Emissions Trading Scheme (ETS) has been practising CO₂ pricing for some industries for several years but does not yet cover agriculture and the LULUCF sector. The carbon dioxide emissions of these sectors, which primarily come from drained peatlands, could be included in the ETS by issuing emission certificates to landowners [69]. Peatland rewetting can result in gross revenue of 2000 EUR/ha/a based on an average mitigation of 20 tonnes of CO₂/ha/a and a CO₂ price of 100 EUR/tonne [75] (p. 48). Combining income from CO₂ certificates with revenues from Peatland PV would remunerate twofold climate benefits and provide a strong incentive for upscaling peatland rewetting.

5. Conclusions

This study clearly shows that Peatland PV as a combination of open-space PV and peatland rewetting may have various synergies. The combined land use can mitigate generally increasing conflicts of land use and reduce land use pressure. The rewetting of peatlands can restore the carbon store function, preserves the existing carbon stock and reduces the GHG emissions of the land use sector. While all potential for PV expansion on conversion sites, buildings, and sealed surfaces must continue to be utilised, the production of renewable energy through Peatland PV holds the potential to further substitute fossil fuels and contribute to energy self-sufficiency and energy security. Thus, through the combination of PV and peatland rewetting, Peatland PV can make a relevant contribution to combating the climate and energy crisis. In the future, the combination of Peatland PV with simultaneous agricultural biomass production, i.e., Paludi PV, can make a further contribution to added value and value creation on land. The construction of PV plants on peatlands without rewetting must be prevented in any case, not only for subsidised plants. If the construction of a PV plant takes place prior to the peatland rewetting, compatibility with rewetting must be ensured and proof of reached target water levels has to be mandatory. This should be ensured by the adaptation and alignment of legislation. Finally, the multiple synergies resulting from combined land use can promote social acceptance. This study elicited a great need for pilot projects and accompanying scientific research to gain further knowledge, to support pioneers in the implementation of Peatland PV, and to specify the need for technological innovations and legal adjustments. Last but not least, real-life data will improve the economic analysis and profitability assessment, which are the prerequisites for estimating the assumed leverage effect for scaling up the rewetting of agriculturally used peatlands.