*Article* **Impact of Subsidy Programmes on the Development of the Number and Output of RES Micro-Installations in Poland**

**Beata Bieszk-Stolorz**

Institute of Economics and Finance, University of Szczecin, 71-101 Szczecin, Poland; beata.bieszk-stolorz@usz.edu.pl

**Abstract:** Renewable energy sources are intended to support the decarbonisation process of the Polish economy. Since 2005, the share of renewable energy in total electricity in Poland has been increasing. The number of photovoltaic panels installed by prosumers as part of micro-installations increased particularly strongly. The aim of this research is an assessment of the impact of government programmes on the development of RES micro-installations in Poland. A regression discontinuity design was used in the analysis. It is a model from the group of average impact effect models used in evaluation studies. The added value of the presented study is its application in the assessment of the impact of implemented programmes on the number and output of micro-installations in Poland. In the study, it is shown that there had been no increase in the number and output of micro-installations at the adopted threshold (2019Q4). On the other hand, there was a sharp increase in them over the whole period starting from 2019Q4.

**Keywords:** renewable energy sources; government regulations; subsidy programmes; prosumers; micro-installations; regression discontinuity design

**Citation:** Bieszk-Stolorz, B. Impact of Subsidy Programmes on the Development of the Number and Output of RES Micro-Installations in Poland. *Energies* **2022**, *15*, 9357. https://doi.org/10.3390/en15249357

Academic Editors: Grzegorz Mentel and Sebastian Majewski

Received: 11 November 2022 Accepted: 8 December 2022 Published: 10 December 2022

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**Copyright:** © 2022 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

#### **1. Introduction**

In 1996, the European Parliament and the European Council adopted the 'White Paper for a Community Strategy and Action Plan' [1]. The Union's objective at the time was to double the share of renewable energy in total gross internal energy consumption. Unfortunately, the enormous potential of renewable energy resources (RES) has still not been realised [2]. The political aim of the European Union is its transformation into a competitive, modern, prosperous, and climate-neutral economy by 2050. To accelerate this transformation, the European Commission presented 'The European Green Deal' in 2019 [3]. It aim was the reduction of over half of greenhouse gas emissions by 2030. The European Union is now the largest political bloc with policy targets to create a climateneutral economy by 2050 [4]. The development of renewable energy sources is linked to the issue of energy security. Jonek-Kowalska [5] showed that the level of energy security for most of the 32 assessed European countries was low due to the predominant use of non-renewable energy resources in their energy mixes. Countries that have a high level of energy security own non-renewable resources or use alternative energy carriers in the form of nuclear power or renewables. EU legislation is forcing the reduction of carbon emissions and the abandonment of non-renewable energy resources and is promoting renewable energy sources. This is a real economic and technological challenge. Such a transformation requires an effective and strategic approach, especially in those countries that have so far mainly used hard coal in the energy sector [6].

In Poland, the Energy Law came into force in 1998 and initiated substantial restructuring and regulation of heat markets and electricity. It introduced a free market for energy and regionally diversified rates. The law favours innovative methods of energy saving and supports clean technologies. It also recognises renewable energy sources as one option to achieve environmental targets in Poland. Nevertheless, the Polish energy system is dominated by coal-fuelled power stations [7]. Renewable energy sources are intended to support

the process of decarbonising economies. A situation in which the renewables can be equally competitive must be cultivated by institutional considerations and inducements [8]. The legal situation is supportive of introducing renewables energy. Prosumers in Poland are largely interested in photovoltaics. The concept of rooftop PVs, also known as "building integrated/applied PV" (BIPV/BAPV) is drawing significant attention. Jurasz et al. [9] emphasise that PVs are almost the only source of electricity that can be used on a large scale in highly populated areas. PV technology requires low maintenance and is noiseand emission-free during its operation phase. Recently, there has been a dynamic increase in the number and output of micro-installations connected to the distribution grid. The majority of them are photovoltaic (PV) installations, of which the dominant majority are prosumer micro-installations connected to the grid on the basis of notification [10]. At the end of 2021, the installed capacity in EU countries reached 158 GW, representing an annual increase of 21.4 GW. Poland was just behind Germany in terms of PV cell growth [11].

#### *Hypothesis and the Research Objective*

In the study, the following hypothesis is put forward:

**Hypothesis (H):** *Regulations and projects implemented in Poland in 2019 have had a positive impact on the increase in the number and output of micro-installations.*

The aim of this article is to estimate the impact of government programmes on the development of RES micro-installations in Poland. Funds for the modernisation and upgrading of energy installations in Poland from the budget are subject to evaluation. The various reports and studies are based on basic statistical research. They do not usually go beyond the scope of descriptive statistics. In this research, an evaluation is carried out using an econometric model. A regression discontinuity design approach was used in the analysis. It is a model from the group of average impact effect models used in evaluation studies. A model using the Regression Discontinuity Design (RDD) in the social sciences was first introduced by Thistlethwaite and Campbell in 1960 [12]. They studied the impact of merit awards on students' future achievements (career aspirations, postgraduate registration, academic achievement, etc.). The RDD has been known for many years. However, its use in scientific research has been quite rare [13]. In socio-economic analysis, it has been used more and more since the late 1990s, with many articles appearing in the fields of labour market, education, environment, forensics, or health [14]. One strand of literature has emerged on measuring the effects of potential benefit duration on unemployment duration [15–18]. Another strand in which RDD has been applied is the impact of regulatory changes on socio-economic phenomenon [19–29].

The added value of the presented study is its application to assess the impact of implemented programmes on the number and output of micro-installations in Poland. An applied econometric model (RDD) allowed a comparison of changes in the years before the subsidy programme was introduced with the period after the introduction of the programme. It was possible to assess the impact at the time of the introduction of the programme, as well as to assess changes over the whole period after its introduction.

#### **2. The Renewable Energy in Poland**

There is an increasing emphasis worldwide on the development of renewable energy sources. Their use is not connected with a long-term deficit, as their resource is renewed in a relatively short time. Such sources include the sun, wind, water (tidal and wave power), closed-cycle nuclear power, biomass, biogas, bioliquids, and biofuels, as well as geothermal, aerothermal, and hydrothermal energy. RES are used, among other things, for the production of electricity.

The production of electricity in Poland depends on the economic situation. Energy demand increases with the economic development of the country. Figure 1 shows two characteristic declines caused by the global crises [30]. Since 2005, the share of renewable

energy in Poland's total electricity production has been increasing. Since 2019, the structure of gross electricity production from renewable energy sources in Poland has changed (Figure 2). The share of photovoltaic power plants has begun to increase in this structure. Particularly rapid growth has occurred in the number of electricity prosumers in Poland (Table 1). Their number was 25,623 in 2017 and 845,505 in 2021, almost 100% of which were prosumers using and producing energy from photovoltaic panels.

**Figure 1.** Total electricity production and share of renewable energy in Poland 2005–2021. Source: own elaboration on the basis of data from https://stat.gov.pl, accessed on 11 November 2022.

**Figure 2.** Gross electricity production from renewable energy sources in Poland 2017–2021 (GWh). Source: own elaboration on the basis of data from https://www.are.waw.pl/, accessed on 11 November 2022.

**Table 1.** Number of electricity prosumers in Poland in 2017–2021. Source: own elaboration on the basis of data from https://www.are.waw.pl/, accessed on 11 November 2022.


One obstacle to the development of renewable energy sources in Poland is the state of the electricity transmission and distribution infrastructure [31]. In order to support investments in RES, it is first necessary to strive to simplify all state administrative procedures concerning investments in this sector. Decisive legal actions creating favourable conditions for RES development ought to be implemented by state authorities. Modification of the RES support system and harmonisation of the interpretation of the regulatory framework would also promote a faster introduction of new renewable energy sources [31]. The potential of renewable energy resources in Poland is high, which indicates real opportunities for further development of the renewable energy sector. According to experts, wind energy, solar energy, and solid biomass processing have the best chances for development in Poland. They point out that the main cause for the slow development of RES in Poland is the coal lobby [32]. Despite many efforts, the public administration in Poland is not conducive to the development of RES, which is often emphasised by owners of RES installations [33]. Administrative simplification is needed to reduce the investment preparation period and the associated costs. Existing procedures must be as simple as possible. The deadlines that individual decision-makers have should be reviewed (shortened if possible) or methods should be found on how to bypass certain systemic preparation stages [34]. Poland is one of the countries whose economy largely depend on energy imports and relies on non-organic energy sources, mainly coal or gas [35].

The rapid development of photovoltaic installations in Poland may exacerbate the problem of the mismatch between evening and daytime electricity demand in households. The Polish electricity system should prepare to stabilise the grid. This is a problem that should be solved in the near future [36].

The literature highlights the fact that the impact of government expenditure on economic development is not unambiguous. It depends on the country studied, the methodology used, the period studied, and the analysed socio-economic phenomenon [37].

A number of programmes are being implemented in Poland with the aim of meeting international obligations in the field of renewable energy, improving air quality, and increasing energy security. Some of them are directly dedicated to renewable energy sources, while others include support for the installation of these sources alongside other measures. Some of these programmes apply to individuals: homeowners or flat owners. Therefore, they concern micro-installations and prosumers.

An RES micro-installation is an installation of RES with a total installed electrical output of no more than 50 kW, connected to an electricity grid with a rated voltage of less than 110 kV or with a cogeneration heat output of no more than 150 kW, where the total installed electrical capacity is no more than 50 kW.

A prosumer is a final consumer purchasing electricity on the basis of a comprehensive contract, generating electricity exclusively from renewable energy sources in a microinstallation, for consumption for their own needs.

On 30 August 2019, the call for applications for the "My Electricity" programme began in Poland. This is the first time such a large nationwide support has been applied for individuals. The programme is a strong impetus for the further development of prosumer energy. The aim of the programme is to increase the production of electricity from photovoltaic micro-installations in the Republic of Poland. Importantly, the obtained subsidy can be combined with the so-called thermo-modernisation relief, which translates into financial efficiency of this support. The fourth edition of this programme was launched in 2022.

Recently, in Poland, the increase in output was mainly due to micro-installations (inter alia, the programme "My Electricity"), and in the near future there should be an increase in the output of large installations supported by the auction system [38].

A similar programme is the "My Heat" programme. Its aim is to support the development of individual heating and prosumer energy development in the area of air, water, and ground source heat pumps in new single-family residential buildings. The programme will run in the period 2022–2026.

The "Clean Air" programme is being implemented in Poland between 2018 and 2029. It is aimed at owners and co-owners of single-family houses, or at separate dwellings in single-family buildings with a separate land register. It is a response to the worsening air quality in Poland. Thanks to the programme, it is possible to apply for subsidies for the replacement of cookers, insulation of buildings, and the installation of photovoltaic panels and heat pumps. The programme aims to increase the energy efficiency of households and reduce or avoid emissions of harmful pollutants introduced into the atmosphere by single-family houses. This is mainly achieved by replacing old solid fuel heat sources with modern heat sources, meeting the highest standards and thermo-modernisation of buildings (e.g., external wall insulation). The "Clean Air" programme can contribute to reducing energy poverty in Poland.

Another programme to be implemented between 2019 and 2027 is "Stop SMOG". It is dedicated to municipalities located in areas where the so-called anti-smog resolution is in force to support the elimination or replacement of heat sources with low-emission ones and thermo-modernisation in single-family residential buildings of the least affluent people.

The "Warm Dwelling" programme will be implemented between 2022 and 2026 and is intended for municipalities, which will then issue an intake in their area for individuals with a legal title arising from ownership or a limited right to a dwelling unit located in a multi-family residential building. It is aimed at replacing all inefficient solid fuel heat sources for heating the dwelling with efficient heat sources or connecting to an efficient heat source in the building.

The transition to an electro-energy system dominated by renewable energy sources requires the consideration of economic, technical, and socio-political, as well as regulatory and institutional, aspects. Any changes in laws and regulations should be made with a full understanding of these aspects, otherwise change processes may be blocked [39]. Currently, a number of regulations are being introduced in Poland as a part of decarbonisation. Their aim is to develop a sustainable energy strategy. Some of these regulations include renewable energy sources. In order to achieve the sustainable development, governments ought to implement cost-effective, environmentally friendly and socially acceptable policies. Czarnecka et al. [40] identified socio-economic characteristics that influence the evaluation of the decarbonisation process in Poland. Respondents were those using central or local funds to conduct this process. The authors showed that, in Poland, financial incentives have the greatest potential for successful decarbonisation. Particularly important are subsidies for changing individual heating infrastructure or for developing prosumer photovoltaics. According to them, these activities should be financed from local resources.

As Rynska [11] points out, the first report on the PV market in Poland was published in 2012. At that time, the output of installations was estimated at 7.9 MW. Initial estimates for the following years turned out to be incorrect. In 2020, production was already higher than proposed for 2030. Even with various policy measures, the strongest incentive can only come from national regulations and financial incentives supporting stakeholders. PV development often does not depend on climatic conditions, but rather on the level of incentives taken by individual countries and the overall policy measures taken at the EU level.

The problem with subsidising renewables in Spain was described by Wuebben and Peters [41]. In 2008, Spain was the world leader in the number and output of photovoltaic installations. During this period, the tariff deficit (the mismatch between government expenditures on subsidies and revenues from taxes and tariffs for electricity) reached record levels in Spain. In the following years, the Spanish government removed incentives for prosumers and even tightened existing regulations. Spain has become one of the most restrictive regulatory regimes of all EU Member States. The setbacks and lack of stable regulation have created an unattractive market for investors. The number of new renewable energy installations has stopped growing [42].

Christoforidis et al. [43] proposed a novel generalised methodology for the technoeconomic assessment of different Net-Metering (NEM) policies with respect to profitability

for the prosumer. They tested the methodology on the example of Greece. They showed that the macroeconomic impacts of NEM are country specific. They affect each economy differently. In order that a policy is successful, it must create a win–win situation for all stakeholders.

#### **3. Methods**

The estimation of the mean impact effect is related to the analysis of dependence between the occurring phenomena. The basic element of these methods is a random variable describing two states: impact (*Y*1) and the lack of impact (*Y*0). The relationship between the empirical and hypothetical results can be presented as follows: *Y* = *dY*<sup>1</sup> + (1 − *d*)*Y*<sup>0</sup> for *d* - {0, 1}. The dependent variable *Y* is modelled as a conditional expected value. It has a known realisation of the vector of observed characteristics, *X*. The mean treatment effect is defined by the formula *ATE* = *E*(*Y*<sup>1</sup> | *X*) − *E*(*Y*<sup>0</sup> | *X*). The regression discontinuity design (RDD) is one of the popular methods of evaluation research.

The study uses the RDD model. Two forms of such models are mentioned in the literature: sharp and fuzzy [44,45]. The sharp form can be used if the cut-off point fully identifies the experimental group. If not, all units on a given side of the cut-off point can be assigned to the experimental group (they still have to satisfy an additional condition), then the fuzzy form of the model ought to be used. In the case of this study, due to a single set of conditions, the sharp form of the model has been used

On each side of the cut-off point, *c*, we estimate the parameters for two separate regression functions. On the left-hand side of the cut-off point, *c*, the function has the form [14]:

$$\mathcal{Y} = \mathfrak{a}\_l + f\_l(\mathcal{X} - \mathfrak{c}) + \mathfrak{c} \tag{1}$$

and on the right:

$$Y = a\_I + f\_I(X - \mathfrak{c}) + \mathfrak{e} \tag{2}$$

Both models (1) and (2) can be written as one:

$$Y = \mathfrak{a}\_I + \pi \, D + f(X - c) + \varepsilon \tag{3}$$

where:

$$
\pi = \alpha\_r - \alpha\_l \tag{4}
$$

$$f(X - c) = f\_l(X - c) + D[f\_l(X - c) - f\_l(X - c)]\tag{5}$$

*D* is a dichotomic variable whose form depends on the position of the experimental group in relation to the defined eligibility threshold, c. If it is defined:

$$D = \begin{cases} 0 \text{ for } X < c \\ 1 \text{ for } X \ge c \end{cases} \tag{6}$$

then the experimental group is defined by the inequality *X* ≥ *c*, and the control group by *X* < *c*.

If *fl* and *fr* have a linear form, the following holds:

$$f\_l(X - \mathcal{c}) = \beta\_l(X - \mathcal{c}) \tag{7}$$

$$f\_r(X - \mathfrak{c}) = \beta\_r(X - \mathfrak{c}) \tag{8}$$

and model (3):

$$\mathcal{Y} = \mathfrak{a}\_l + \mathfrak{r}\,D + \beta\_l(X - \mathfrak{c}) + \beta D(X - \mathfrak{c}) + \mathfrak{e} \tag{9}$$

where *β* = *β<sup>r</sup>* − *βl*.

In model (9), the parameter *τ* reports the change in the value of the variable *Y* when passing the threshold. If this parameter is positive, there has been an increase in the threshold, if negative, there has been a decrease in the value of the dependent variable. The parameter *β*, on the other hand, reports whether there has been a change in the rate of change in the growth of the dependent variable after passing the threshold.

The study uses data from Statistics Poland [7]. These are only annual data and do not detail the types of renewable energy sources. For this reason, data collected by The Energy Market Agency (ARE) [46] and Polish Power Transmission and Distribution Association [47] were also used. The quarterly data contained therein enabled the construction of the RDD model. Data on the number of micro-installations and micro-installation output in Poland from 2017Q2 to 2022Q2 were used to construct the model.

#### **4. Data Analysis**

At the outset, the research period was established. Due to data availability, quarterly data were included in the modelling. We mark the subsequent years as *Xi* for *i* = 1, 2, ... , 21; 2017Q2 (the first observed quarter) is defined as 1 (*X*<sup>1</sup> = 1), and quarter 2022Q2 (the last observed) as 21 (*X*<sup>21</sup> = 1). Preliminary analysis of the data is shown in Figure 2 and Table 1, and a review of the programmes targeting prosumers allowed us to assume the threshold as (*X*<sup>11</sup> = *X*<sup>0</sup> = 11) (2019Q4). This estimate of the number and the output of micro-installations, *Yi*, was used in two models. Each has the general form of:

$$\hat{Y}\_i = \mathfrak{a}\_l + \tau D + \beta\_l (X\_i - X\_0) + \beta D (X\_i - X\_0) \tag{10}$$

where:

*Yi*—number of micro-installations (output of micro-installations);

*Xi*—quarter number;

*τ*—average impact of the change of regulations on the number of micro-installations (output of micro-installations) at the threshold *X*<sup>0</sup> = 11.

We define the dummy variable, *D*, as follows:

$$D = \begin{cases} 0 \text{ for } 1 \le X\_i < 11\\ 1 \text{ for } 11 \le X\_i \le 21 \end{cases} \tag{11}$$

Parameter estimates are shown in Table 2.

**Table 2.** Number of electricity prosumers in Poland in the period 2017–2021.


For the number of micro-installations, the following models were obtained:

$$
\dot{Y}\_i = 1873.06 + 8744.70 X\_i \text{ for } D = 0 \tag{12}
$$

$$\hat{Y}\_{\text{i}} = -995, 896.04 + 97, 679.90 \text{X}\_{\text{i}} \text{ for } D = 1 \tag{13}$$

For the output of micro-installations [MW] the following models were obtained:

$$
\hat{Y}\_i = 11.21 + 56.26X\_i \text{ for } D = 0 \tag{14}
$$

$$
\hat{Y}\_i = -7754.35 + 731.89X\_i \text{ for } D = 1 \tag{15}
$$

Equations (12) and (14) describe the linear models of the number and the output of microinstallations before 2019Q4, respectively. Equations (13) and (15) describe the linear models of the number and the output of micro-installations starting from 2019Q4, respectively. The RDD models (12)–(15) are shown in Figures 3 and 4.

**Figure 3.** The regression discontinuity design models for the number of micro-installations in Poland.

**Figure 4.** The regression discontinuity design models for the output of micro-installations in Poland.

The following conclusions can be drawn from the estimations in Table 2:


increased. However, the lack of significance of these parameters informs the fact that this growth was slow from quarter to quarter.

• The estimators of the *β* parameter were statistically significant and positive for both models. Comparing the slope parameters in models (12) and (13), as well as (14) and (15), one can see a clear sharp increase in their values. This means that since 2019Q4 the number and output of micro-installations started to increase rapidly.

#### **5. Discussion**

The analysis confirms the results of other studies. The RES subsidy programmes introduced in Poland for prosumers have significantly increased the number of RES and the output of energy production. Kata et al. [48] analysed the role of municipalities in the adaptation of RES installations in residents' households. Municipalities promote renewable energy in the "civic" segment primarily through the introduction of the so-called umbrella projects. They also positively influence RES adaptation through the mimicry effect, also in other households in the nearest neighbourhood. The imitation effect results in more inhabitants taking an interest in RES investments and expecting support from the municipality. These expectations relate to the co-financing of the installation, information, and consultancy support. It is the imitation effect that causes a rapidly growing interest in a particular programme. This was particularly evident after the introduction of the "My Electricity" programme. In Poland, the number of companies offering the installation of photovoltaic panels increased in the period 2020–2021 despite the ongoing pandemic, and so did the number of realised orders. The results obtained with the RDD model also indicate a rapid interest in the programme.

Zdonek et al. [49] attempted to evaluate the "My Electricity" programme for increasing renewable energy production in prosumer photovoltaic (PV micro-installations) sources in Poland. The evaluation was performed from the perspective of business, beneficiaries, and the local community. The authors concluded that the beneficiaries evaluated the surveyed programme rather well. Owners of small PV installations felt that the subsidy covered by the programme was a good motivation. Owners of larger PV installations prefer the subsidy being a percentage, not an amount. The cooperation with companies installing domestic PV systems and the process of handling the application for grants were also positively assessed by the beneficiaries. This positive assessment is reflected in the number of new PV sources installed and the output of new connections. The "My Electricity" programme has contributed to approximately 2 GWp of installed PV capacity between 2019 and 2021. The total cost of the programme on the state side is approximately EUR 390 million in direct subsidies and additional tax credits for prosumers [50]. The research in this paper is in line with these findings.

The process of growth in the overall share of energy from renewable sources in Poland follows the upward European trend (Figure 5). The exception in Poland is the year 2017, when there was a decrease and then an increase in the share due to changes in legislation and subsidies favourable to prosumers. However, despite these favourable changes, Poland's situation differs significantly from that of other European countries. Although the average overall share of energy from renewable sources in Poland is not much lower than the average for EU countries, Poland ranks among the last in Europe in 2020 (Figure 6). The situation of Poland is slightly better in relation to other European states in terms of the share of RES in total electricity production (Table 3). In Poland, most electricity from RES is produced in wind power plants. The changes analysed in the research part of the article concern electricity produced in prosumer micro-installations, which mainly concern solar installations. If the favourable changes in legislation and investment subsidies do not worsen, the number of these installations and their capacity will certainly continue to grow. This is because the overall aim is to increase the overall share of energy from renewable sources and to become independent of foreign supplies of energy resources.

**Figure 5.** Overall share of energy from renewable sources, 2004–2020, EU27 from 2020 (%). Source: own elaboration on the basis of data from https://ec.europa.eu/eurostat/web/energy/data/shares, accessed on 11 November 2022.

**Figure 6.** Overall share of energy from renewable sources in 2020 (%) in selected European countries. Source: own elaboration on the basis of data from https://ec.europa.eu/eurostat/web/energy/data/ shares, accessed on 11 November 2022.

The development of RES in Poland depends on the level of public awareness in all consumer groups. The results of a study by Maciaszczyk et al. [51] showed that there is a relationship between the respondents' age and education and their readiness to consider renewable energy issues and implement them in their households. Awareness of the importance of RES increases slightly with the age of the respondents and their level of education. However, these variables did not significantly influence the decision to install RES in the household. The implication is that potential prosumers in Poland are still in the phase of following the RES market.

As Pietrzak and Kuc-Czarnecka [52] emphasise for the RES sector, there should be a focus, not on independent RES, but on the energy mix. Any regulations and implemented projects should allow the creation of cogeneration from different renewable sources. This direction of development of energy markets should increase the level of energy security, both in analysed countries and worldwide.


**Table 3.** Share of RES in total production of electricity and share of main RES sources in total RES in European countries in 2020. Source: own elaboration on the basis of data from https://ec.europa.eu/ eurostat/web/energy/data/shares, accessed on 11 November 2022.

#### **6. Conclusions**

The conducted analysis confirmed the hypothesis. Regulations and projects implemented in Poland 2019 have had a positive impact on the increase in the number and output of micro-installations. The main contributor to this was the "My Electricity" programme. Due to the character of the investment, this change did not occur immediately, but several months after the introduction of the favourable programme. There was a sharp increase in the number of micro-installations and their output. A new Renewable Energy Sources Act came into force in Poland on 1 April 2022. The profitability of photovoltaics under the new system will be lower. The new system is not as favourable for prosumers as the previous one. The return on investment will extend by several years. This does not mean the end of the prosumer. Photovoltaics will still be more profitable than paying the usual electricity bills. The change in legislation will provide the impetus for further research into the impact of regulation on the development of RES in Poland. However, it will be necessary to wait for new data on the energy market in Poland.

One limitation of the research is the access to data. They are usually only available on an annual basis. This is because such a high degree of data aggregation makes it impossible to directly track changes over the year. Another problem is the lack of data by different energy sources, as well as the lack of data distinguishing micro-installations. In addition, data published by different institutions differ. Hence, the analyses appearing in the literature differ in the results obtained. However, the assessments of changes in the access and use of renewable energy sources are the same. Studies confirm the increase in the use of RES in Poland, especially by prosumers.

This article can be an important source of information for policy makers and creators of energy policy in Poland. Any new legal regulations may have a positive or negative impact on prosumer behaviour. This is especially important in the case of economic crises. Measures to mitigate the current energy crisis in Europe should be based on scientific research in the particular area. Thus, future legal regulations are largely likely to contribute to the rapid growth of micro-installation, or its decline.

**Funding:** The project is financed within the framework of the program of the Minister of Science and Higher Education under the name "Regional Excellence Initiative" in the years 2019–2022; project number 001/RID/2018/19; the amount of financing was PLN 10,684,000.

**Data Availability Statement:** Contained within the text and cited references.

**Conflicts of Interest:** The author declares no conflict of interest.

#### **References**

