Increasing the Efficiency of Ecological Solar Panels Combined with the Building’s Roof
, Mariana Kasynets 1, Stepan Shapoval 1, Olena Savchenko 1, Iryna Sukholova 1, Nadiia Spodyniuk 2 and Oleksandr Dovbush 1Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsI would like to highlight that the issue addressed is complex, as one of the major drawbacks in implementing a solar panel is finding a balance between maximum efficiency and the lowest cost possible. Thus, the authors aim to optimize these parameters by combining solar panels with building elements. In my perspective, the paper is interesting but needs improvements. Here is my suggestion to improve the quality of the paper:
- The authors propose dividing the 6-factor experimental part into two 3-factor parts; however, they do not provide an adequate justification for this division. The explanation could be more detailed on why this approach is advantageous or necessary.
- Line 253: please correct the reference.
- The description of the solar panel components is given, but there is a lack of information on how these components were selected or how they contribute to the panel's efficiency.
- How may the laboratory conditions differ from the field conditions? This should be addressed.
- Are 30-minute intervals sufficient to capture significant variations in environmental conditions or panel performance?
- The formulas provided on line 314 do not have enough resolution. Please improve.
- What are the possible limitations or challenges of the proposed system? Discussions on limitations and future directions are important parts of scientific conclusions. The authors should improve the conclusion section.
- The conclusion regarding the influence of tube diameter only under low radiation intensity is interesting but not adequately explored. Details on the specific levels of radiation intensity and how this affects panel efficiency are interesting. If possible, it should be included in the manuscript.
Comments on the Quality of English LanguageThe quality of English language is fine
Author Response
Reviewer 1
I would like to highlight that the issue addressed is complex, as one of the major drawbacks in implementing a solar panel is finding a balance between maximum efficiency and the lowest cost possible. Thus, the authors aim to optimize these parameters by combining solar panels with building elements. In my perspective, the paper is interesting but needs improvements. Here is my suggestion to improve the quality of the paper:
- The authors propose dividing the 6-factor experimental part into two 3-factor parts; however, they do not provide an adequate justification for this division. The explanation could be more detailed on why this approach is advantageous or necessary.
Designing a complete 6-factor experiment is an extremely complex process. The experimental planning matrix must follow Newton's binomial rule. According to this rule, such a matrix has 26=64, namely 64 rows and 64 columns, that is, it is quite bulky. In this regard, it is proposed to divide the 6-factor problem into two 3-factor ones, each of which has 8 rows and 8 columns, respectively. This is more than obvious, it simplifies the situation, therefore it is beneficial and absolutely necessary. However, it requires a number of assumptions, which are described in the text on page 7, item 4.1: “the radiation intensity, the type of tubes, and the solar panel coverage are represented by a conditionally constant value”.
- Line 253: please correct the reference.
Reference (line 253) is corrected.
- The description of the solar panel components is given, but there is a lack of information on how these components were selected or how they contribute to the panel's efficiency.
Since these systems are elements of buildings, their installation can be foreseen both in new construction and in the reconstruction of the building, which will increase the efficiency of the system as a whole and reduce the payback period. The selection of components was carried out in such a way as to make maximum use of the elements of the building, in particular the existing roof covering, as a basis for the solar panel. Only the main elements that ensure the circulation of the heat carrier along the circuit have been added.
- How may the laboratory conditions differ from the field conditions? This should be addressed.
In order to confirm the laboratory studies, field tests were carried out, since it is impossible to reproduce the effect of all factors affecting the operation of the system as a whole. Research in laboratory conditions provides an opportunity to select controllable determining factors to establish the nature of their influence on the selected response function. Since the efficiency coefficient is a relative value, not an absolute one, it is important to analyze its change from selected factors and determine ways to increase it. In addition, comparisons of this method of laboratory research with field studies of the same installations, which are presented in other scientific works, were carried out.
- Are 30-minute intervals sufficient to capture significant variations in environmental conditions or panel performance?
The authors' research shows that for flat solar collectors, the deviation of solar radiation within 15 degrees from the perpendicular arrival on the surface of the absorber has almost no effect on its efficiency. Therefore, the minimum research time of 30 min was chosen, since the conditions of the arrival of solar radiation, namely the angles of its arrival on the surface of the heat sink, change further. Before the start of the experiment, the solar panel was shaded with a screen and the heat emitters were turned on, after they reached their maximum power (up to 15 min), the shading screen was removed and the solar panel was heated for 30 min (after which the temperature changes of the layers in the solar panel were not recorded). The required heat carrying medium flow rate was set, which was kept constant throughout the experiment. Measurements were made every 10 minutes. During field studies, significant fluctuations in the environment were not recorded.
- The formulas provided on line 314 do not have enough resolution. Please improve.
Resolution of the formulas on lines 322 – 328 now is improved.
- What are the possible limitations or challenges of the proposed system? Discussions on limitations and future directions are important parts of scientific conclusions. The authors should improve the conclusion section.
The conclusion section is improved.
The proposed system is quite relevant in today's conditions of increasing traditional energy sources and the general plan of decarbonization of the planet. However, the use of these systems has certain limitations, namely: the problem of condensation in the middle of the structure, during sudden changes in weather conditions, and in regions with a significant cold period and low solar activity. Therefore, the use of these panels is not possible for all climatic regions, which may be determined by the periodicity of work; in addition, a significant increase in mass on the facade may be a limitation, which may not always contribute to the structural stability of the building and will require additional structural solutions.
- The conclusion regarding the influence of tube diameter only under low radiation intensity is interesting but not adequately explored. Details on the specific levels of radiation intensity and how this affects panel efficiency are interesting. If possible, it should be included in the manuscript.
The authors agree that this aspect has not been sufficiently investigated. In this work, research was planned only at 2 values of solar radiation intensity: 500 W/m2 and 1000 W/m2. It is added on page 10, lines 326 – 328 as “The direction of the future research”: “In addition, it is advisable to conduct research at other values of the intensity of solar radiation, for example 700 - 800 W/m2 and 1200 - 1300 W/m2”. It is also included in conclusion item.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsI make the following comments to the manuscript:
The introduction should take a broader account of the global state of knowledge. Literature research was too much limited to the local bibliography. Must be completed.
Explain why only 2 panels were tested? How was their orientation relative to the cardinal directions chosen?
The charts (Fig. 7 to 10) and their descriptions are not entirely legible. It is suggested to refine them (including graphic correction of text 314-315).
The conclusions are too short. They do not refer to a broader view of the presented topic, in particular in relation to the existing state of knowledge.
The entry in lines 78-82 is too general. After all, it depends on many factors. For correction
No descriptions in Fig. 5 - need to be corrected.
Author Response
Reviewer 2
I make the following comments to the manuscript:
The introduction should take a broader account of the global state of knowledge. Literature research was too much limited to the local bibliography. Must be completed.
The introduction is corrected and completed.
Explain why only 2 panels were tested? How was their orientation relative to the cardinal directions chosen?
The research was preceded by the analysis of literature data and the authors' own experience, so two typical types of pipelines that could currently be used for the production of test samples were chosen. In addition, it was believed that the sun's rays shine at a right angle, because known methods recommend that this is how to study the thermal characteristics of solar collectors in laboratory conditions, in order to obtain the most reliable results. Since these systems are building elements, the selection of components was made in such a way as to make maximum use of the building elements. In this case, it is the existing roof covering as a basis for the solar panel. Only the main elements that ensure the circulation of the heat carrier along the circuit have been added. The orientation relative to the cardinal points was not taken into account, since the solar panel is combined with the roof covering, that is, it is an element of the building, which, due to the structural features of flat roofs, is horizontal and has no an orientation concerning rhombus.
The charts (Fig. 7 to 10) and their descriptions are not entirely legible. It is suggested to refine them (including graphic correction of text 314-315).
Descriptions of the charts (Fig. 7 to 10) are refined (including graphic correction of text 314-315).
The conclusions are too short. They do not refer to a broader view of the presented topic, in particular in relation to the existing state of knowledge.
The conclusions are corrected. However, these studies showed sufficient thermal efficiency of the proposed solar panel, which reached more than 50%. It should be taken into account that this type of solar collector is low-temperature, so at this stage this is a good indicator and indicates the possibility of applying these technical solutions, especially this is relevant for pre-heating the heat carrier in heat supply systems, or with the subsequent increase in potential with the help of heat pumps. But this is the subject of future research.
The entry in lines 78-82 is too general. After all, it depends on many factors. For correction
Text in lines 91 – 94 now is corrected. Authors are agree, that this value depends on many factors. However, if we accept certain simplifications, averaging and generalizations, in particular regarding the geographical location of the city, the intensity of solar radiation, the design of the panel, etc., then on a sunny summer day in Ukraine, the productivity of a flat panel with 1 m2 of its surface per day can reach 50 liters of water with a temperature of up to 50 - 60 0C.
No descriptions in Fig. 5 - need to be corrected.
Descriptions in Fig. 5 have been added.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThank you for your report. The paper can be accepted in the present form.
