Evaluation of Energy Harvesting for Economically Developing Region for Competent Interexchange Between Energy Supply from Fossil Fuel and Renewable Energy from Solar PV

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper addresses an important topic with potential implications for renewable energy adoption in developing regions, however, it requires substantial revision to meet scientific publication standards. This methodology needs to be strengthened, the analysis deepened, and the presentation significantly improved. I recommend a major revision with particular attention to clarifying the research questions, improving the methodological rigor, and enhancing the overall clarity and organization of the manuscript.

1. The regression equation must be explained in detail, specifying the meaning of each variable. Moreover, provide details on how the regression model was validated.
2. The R² value alone is insufficient to demonstrate model fit without residual analysis or additional diagnostics.
3. Figures illustrating variable correlations should be consolidated and better explained.
4. The rationale for grouping data by seasons and its impact on solar PV performance requires clearer justification.
5. Conclusions regarding solar power production by data group are not clearly supported by the results.

 Additionally, the introduction should:

1) Clearly state the research gap and specific research questions.

2) Offer more context on South Africa’s energy landscape, particularly the challenges faced in KwaZulu-Natal.

3) Add more recent literature on solar PV implementation in comparable settings.

 

 

Author Response

The regression equation must be explained in detail, specifying the meaning of each variable. Moreover, provide details on how the regression model was validated.

The R² value alone is insufficient to demonstrate model fit without residual analysis or additional diagnostics.

• Residual analysis was considered in the study and it equal an error in prediction. Error is considered in calculation

Figures illustrating variable correlations should be consolidated and better explained.

• An explanation in introductory of all figures was included in the article.

The rationale for grouping data by seasons and its impact on solar PV performance requires clearer justification.

• Through the addition of literature to justify solar PV performance in the region of KZN for better implementation has now been added.

Conclusions regarding solar power production by data group are not clearly supported by the results.

• Comparison of data grouping and season was made to align with an aim of the article.

 Additionally, the introduction should:

 

1) Clearly state the research gap and specific research questions.

- Revised the problem statement and added research questions.

2) Offer more context on South Africa’s energy landscape, particularly the challenges faced in KwaZulu-Natal.

- literature based on South African situation was included to paint the picture.

3) Add more recent literature on solar PV implementation in comparable settings.

- Recent literature was added.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Editors and Authors!

The work is devoted to the topical issue of studying the use of renewable energy sources. At the same time, there are a number of critical comments and issues to the text of the presented work that need to be addressed before recommending it for publication.

 

1. «Weak» Introduction.  The essence of the issue considered in the article is not sufficiently substantiated. There is practically no argumentation as to why this is important. The authors do not indicate the current state of the issue, confirmed by the relevant literature references. What studies have been conducted in this area, etc. It would also be useful to include an image of the region that the authors are studying.
2. Please clearly justify the relevance of the problem, indicate the purpose of the work, its novelty, the general and specific contribution of this work, where the results obtained are applicable.
3. Line 42. "The South African government has supported the promotion of renewable energy throughout the globe such as China." Provide a link confirming this statement.
4. Line 47 and below. "The Western Cape has successfully installed solar energy with minimal failure rates"; «South African looked up to countries such Germany, America and China which have successfully installed solar energy and developed relevant technology that will promote or improve their ecological situation.»; «From one South African Province to another, the comparison and implementation of solar energy has not been largely successful»; Provide references to support each of these statements.
5. Line 57. «Several solar energy harvesters have been installed in KZN; however, the failure rate have consistently gone downward through the infrastructure and technological installation».
6. Line 61. «The study intends to demonstrate solar PV adaptable in the region of KZN as [4] Believes that Photovoltaic system is one of the profitable systems without storage technology.» It is not clear what the reference [4] refers to.
7. Line 467 and below. «Use full justification … (pp. 1-4)». How is this text related to the Introduction? Please justify in the text of the article what these statements are and how they relate to the authors' research. If necessary, provide references to the source(s).
8. Line 78. "Section 1 provides an introduction which has background of renewable energy, a problem statement of the study, the method used, the aims and objectives, and an overview of the significance of the study and research questions". This statement does not correspond to the content of Section 1. See the comments above.
9. Line 98. "Data utilized in this study on solar energy was extracted from the database of regional municipality under the department of renewable energy". Please provide more detailed information about "regional municipality" and "department of renewable energy" and the data obtained. Provide an appropriate reference to the source of the data. If this is classified information, do the authors have the right to use the obtained data for processing and presentation?
10. Line 102. And below. "3.1 Sample and population". Provide more specific information in this section. (number, placement, size, time range, etc.)
11. Line 125. "Multiple regression analysis is the most suitable regression approach since it is a statistical technique that mostly analyses the relationship between a single dependent variable and several independent variables." Provide a reference to support this statement.
12. Line 131. "if the value p". Specify what the value "p" means.
13. Line 136. And further in the text "for example, (Bewick et al., 2010), Rawski et al., (2016)" etc. Use a uniform approach to indicate references (square brackets).
14. There is a discrepancy between the references (14) and their citations in the text (e.g., [15 & 16], (Bewick et al., 2010), (Fang, 2013), Rawski et al., (2016), etc.). Please, align the number of references and their citations in the text.
15. Line 133. Specify what the value of " ε" in the formula means. If this is the formula used by the authors, then provide a link to the source or indicate that this is the author's approach.
16. How do the equations in lines 133 and 139 differ from each other? Justify why this particular form of regression dependence was chosen in this work. Provide references if necessary.
17. The designations of the elements of equation (1) are incorrect. In the equation, they have indices, while in the explanation there are no indices.
18. Line 147 «Decisions are influenced by the results obtained from the analysis including the regression results.»; « To improve the status, it is necessary to overlook the cause of failure or possible causes of failure.» Provide references to support each of these statements. What «Decisions» are the authors talking about? Provide a more detailed description
19. Line 151. «The coefficient of determination…». Where is this coefficient and its designation given?
20. Line 158. If this is the formula used by the authors, then provide a link to the source or indicate that this is the authors' approach. Provide the designations of all elements used in the equation. How do these elements correlate with formula (1)
21. Use a unified approach to designate the same quantities (e.g., r² and R2, V0 and V_0, x1 and X1, P and p, etc.).
22. Line 165 and below. The authors do not provide any references to the temperature data obtained. In some places, the designation 0C is missing, and the statement "This is the coldest period of the KwaZulu Natal region as well as other part of the world" is also unfounded.
23. The logical structure of the article is broken, for example, in "3. Results" the authors discuss "group 2" without explanation, and then below, in Table 2, provides an idea of what exactly is being divided into groups, the authors use formula (1), where x1, x2, x3 are indicated, whereas further in the work, in Table 1, x1, x2, x3, x4, x5 are already used.
24. Line 174. "x indicate independent variable (e.g. solar power consumption, Temperature)." This statement does not correlate with the text in Section 2 and in Table 1.
25. Line 178. "The variables presented in Table 1 above were obtained from the database of eThekwini Municipality". Table 1 does not provide any data. It is not clear whether the authors use data only from eThekwini Municipality or for the entire region of KwaZulu Natal, as stated in the text of the article.
26. Line 179. "The temperature, period and solar radiation were collected directly from the renewable energy as well as in the historical information." This statement does not correlate with the text given in Section 2 and Table 1. The dimensions of these quantities also do not correlate with the dimensions presented in Table 1. If these are different data,
27. Line 195. "The solar power grouped using categories months in the table 3." does not correlate with the contents of Table 3 "Table 3: Independent variable significance indication"
28. Line 197. "The solar system parameter, which is the dependent variable are investigated throughout all independent variable (consumption, solar import, energy export, solar self-consumption and temperature)." does not correlate with the parameters of Table 2.
29. Lines 197-204. It is not clear from the text of the article whether temperature is a parameter under consideration or not
30. It is not clear how the data (and what they represent) were obtained in Fig. 1-16. Table 2 only gives an idea of the breakdown of the data into groups. What kind of data this is, how they correlate with each other over time or in any other way is not clear from the text of the manuscript. Why they are presented in this particular form in Fig. 1-4, 5-8, 9-12, 13-16 is not clear.
31. Line 331. "The reason for outlining data grouping throughout the is to demonstrate the performance among the parameters during the different season and weather conditions." How did the authors track the change in weather conditions over time? Or is this data for only one year? Can other factors influence these parameters and why? The authors do not discuss this in the transcript.
32. It is not clear how the data in Table 3 were obtained.
33. It is not clear how the authors move from regression analysis (section 3.1-3.2) to multiple regression model (section 4.6)
34. Line 351. "In summary, the table 4.10 below demonstrate the following that". Table 4.10 is missing from the text.
35. Overall, section "4.6 APPLICATION OF MULTIPLE REGRESSION MODEL" seems to be taken out of context. There is no justification for the applicability of the model, no explanation of what the parameters in tables 3-5 are, how these coefficients were obtained, if above (section 3.1, 3.2) the authors spoke about linear regression. The discussions that are carried out in this section come before section 4 "Discussion", which also does not correspond to the logic of the article.
36. It is not clear how the coefficients of table 4 were obtained, which are then used in "the projected model " in the "Discussion" (line 378).
37. Line 389. Perhaps a formula (table) is missing?
38. The conclusions contain a conclusion on the results of the study. On what basis did the authors include the figure?!
39. Line 416. "Solar power production (Wh) in the DG 1 shows an almost 32% of solar power to be produced in this term [7]." It is not clear why the authors use a reference to a literary source in the conclusions.
40. How were the data for Fig. 5 (in the Conclusions) obtained? The figure numbering is duplicated.
41. References [7]. Provide a full, correct reference to the source.
42. It should also be noted that the work is poorly structured and substantiated. There are critical discrepancies between the presented data and the results obtained. The presentation of data in different sections of the manuscript differs. The information is presented in a very generalized form, in vague phrases, which is not acceptable in a scientific publication. The conclusions, on the contrary, are very specific. There is no substantiation of the approach used. The numbering of sections, tables, and figures is inconsistent (for example, the sequence of sections: section 2, section 3, and immediately section 4.6; table 4.10; fig. 4.23; fig. 5 is duplicated twice). In general, the work gives the impression of disparate parts connected without logical sequence.

Author Response

«Weak» Introduction.  The essence of the issue considered in the article is not sufficiently substantiated. There is practically no argumentation as to why this is important. The authors do not indicate the current state of the issue, confirmed by the relevant literature references. What studies have been conducted in this area, etc. It would also be useful to include an image of the region that the authors are studying.

• Modified and added research questions

Please clearly justify the relevance of the problem, indicate the purpose of the work, its novelty, the general and specific contribution of this work, where the results obtained are applicable.

• Revised the research problem

Line 42. "The South African government has supported the promotion of renewable energy throughout the globe such as China." Provide a link confirming this statement.

• Improved the statement and supported with literature.

Line 47 and below. "The Western Cape has successfully installed solar energy with minimal failure rates"; «South African looked up to countries such Germany, America and China which have successfully installed solar energy and developed relevant technology that will promote or improve their ecological situation.»; «From one South African Province to another, the comparison and implementation of solar energy has not been largely successful»; Provide references to support each of these statements.

• Referenced

Line 57. «Several solar energy harvesters have been installed in KZN; however, the failure rate have consistently gone downward through the infrastructure and technological installation».

• Reconstructed the sentence for better understanding

Line 61. «The study intends to demonstrate solar PV adaptable in the region of KZN as [4] Believes that Photovoltaic system is one of the profitable systems without storage technology.» It is not clear what the reference [4] refers to.

• The sentence was reconstructed

Line 467 and below. «Use full justification … (pp. 1-4)». How is this text related to the Introduction? Please justify in the text of the article what these statements are and how they relate to the authors' research. If necessary, provide references to the source(s).

• The text was removed from the manuscript since it was not related.

Line 78. "Section 1 provides an introduction which has background of renewable energy, a problem statement of the study, the method used, the aims and objectives, and an overview of the significance of the study and research questions". This statement does not correspond to the content of Section 1. See the comments above.

• The structure was followed and research question was incorporated as well.

Line 98. "Data utilized in this study on solar energy was extracted from the database of regional municipality under the department of renewable energy". Please provide more detailed information about "regional municipality" and "department of renewable energy" and the data obtained. Provide an appropriate reference to the source of the data. If this is classified information, do the authors have the right to use the obtained data for processing and presentation?

• eThekwini municipality is regional municipality with a special department of renewable energy focusing in solar energy mostly.

Line 102. And below. "3.1 Sample and population". Provide more specific information in this section. (number, placement, size, time range, etc.)

• The study time and range was between 2015 and 2020 and 12 months focus data was used within the range.

Line 125. "Multiple regression analysis is the most suitable regression approach since it is a statistical technique that mostly analyses the relationship between a single dependent variable and several independent variables." Provide a reference to support this statement.

• Referenced

Line 131. "if the value p". Specify what the value "p" means.

• It p-value where p represents probability

Line 136. And further in the text "for example, (Bewick et al., 2010), Rawski et al., (2016)" etc. Use a uniform approach to indicate references (square brackets).

• The references were replaced with latest reference

There is a discrepancy between the references (14) and their citations in the text (e.g., [15 & 16], (Bewick et al., 2010), (Fang, 2013), Rawski et al., (2016), etc.). Please, align the number of references and their citations in the text.

• Replaced within new references.

Line 133. Specify what the value of " ε" in the formula means. If this is the formula used by the authors, then provide a link to the source or indicate that this is the author's approach.

• The value -ε is insignificant but considered in the calculation.

How do the equations in lines 133 and 139 differ from each other? Justify why this particular form of regression dependence was chosen in this work. Provide references if necessary.

• 139 represents the multiple regression and the 133 is the standard of regression formular.

The designations of the elements of equation (1) are incorrect. In the equation, they have indices, while in the explanation there are no indices.

• Corrected and aligned with research

Line 147 «Decisions are influenced by the results obtained from the analysis including the regression results.»; « To improve the status, it is necessary to overlook the cause of failure or possible causes of failure.» Provide references to support each of these statements. What «Decisions» are the authors talking about? Provide a more detailed description

• More description is given on the paragraph

Line 151. «The coefficient of determination…». Where is this coefficient and its designation given?

• The coefficient of determination is introduced in this line and values are given on the results and discussion.

Line 158. If this is the formula used by the authors, then provide a link to the source or indicate that this is the authors' approach. Provide the designations of all elements used in the equation. How do these elements correlate with formula (1)

• Designation is also included in the study

Use a unified approach to designate the same quantities (e.g., r² and R2, V0 and V_0, x1 and X1, P and p, etc.).

• The summary of these values is given in the conclusion.

Line 165 and below. The authors do not provide any references to the temperature data obtained. In some places, the designation 0C is missing, and the statement "This is the coldest period of the KwaZulu Natal region as well as other part of the world" is also unfounded.

• Referenced

The logical structure of the article is broken, for example, in "3. Results" the authors discuss "group 2" without explanation, and then below, in Table 2, provides an idea of what exactly is being divided into groups, the authors use formula (1), where x1, x2, x3 are indicated, whereas further in the work, in Table 1, x1, x2, x3, x4, x5 are already used.

• Referenced the regression analysis.

Line 174. "x indicate independent variable (e.g. solar power consumption, Temperature)." This statement does not correlate with the text in Section 2 and in Table 1.

• Solar variables are represented by x.

Line 178. "The variables presented in Table 1 above were obtained from the database of eThekwini Municipality". Table 1 does not provide any data. It is not clear whether the authors use data only from eThekwini Municipality or for the entire region of KwaZulu Natal, as stated in the text of the article.

• Reconstructed the sentence.

Line 179. "The temperature, period and solar radiation were collected directly from the renewable energy as well as in the historical information." This statement does not correlate with the text given in Section 2 and Table 1. The dimensions of these quantities also do not correlate with the dimensions presented in Table 1. If these are different data,

• Reconstructed the information related to the table 1.

Line 195. "The solar power grouped using categories months in the table 3." does not correlate with the contents of Table 3 "Table 3: Independent variable significance indication"

• Aligned with the table 3 to fit the data group

Line 197. "The solar system parameter, which is the dependent variable are investigated throughout all independent variable (consumption, solar import, energy export, solar self-consumption and temperature)." does not correlate with the parameters of Table 2.

• Aligned with table 2 and parameters

Lines 197-204. It is not clear from the text of the article whether temperature is a parameter under consideration or not

• Reconstructed the paragraph

It is not clear how the data (and what they represent) were obtained in Fig. 1-16. Table 2 only gives an idea of the breakdown of the data into groups. What kind of data this is, how they correlate with each other over time or in any other way is not clear from the text of the manuscript. Why they are presented in this particular form in Fig. 1-4, 5-8, 9-12, 13-16 is not clear.

• All the statistical and presented in the graph.

Line 331. "The reason for outlining data grouping throughout the is to demonstrate the performance among the parameters during the different season and weather conditions." How did the authors track the change in weather conditions over time? Or is this data for only one year? Can other factors influence these parameters and why? The authors do not discuss this in the transcript.

• We tool information from the department of renewable and used the statistical

It is not clear how the data in Table 3 were obtained.

• Re-introduced on the paragraph

It is not clear how the authors move from regression analysis (section 3.1-3.2) to multiple regression model (section 4.6)

• Reconstructed paragraph

Line 351. "In summary, the table 4.10 below demonstrate the following that". Table 4.10 is missing from the text.

• Reconstructed the statement

Overall, section "4.6 APPLICATION OF MULTIPLE REGRESSION MODEL" seems to be taken out of context. There is no justification for the applicability of the model, no explanation of what the parameters in tables 3-5 are, how these coefficients were obtained, if above (section 3.1, 3.2) the authors spoke about linear regression. The discussions that are carried out in this section come before section 4 "Discussion", which also does not correspond to the logic of the article.

It is not clear how the coefficients of table 4 were obtained, which are then used in "the projected model " in the "Discussion" (line 378).

• Reconstructed the sentence.

Line 389. Perhaps a formula (table) is missing?

• Formular inserted

The conclusions contain a conclusion on the results of the study. On what basis did the authors include the figure?!

• Reconstructed

Line 416. "Solar power production (Wh) in the DG 1 shows an almost 32% of solar power to be produced in this term [7]." It is not clear why the authors use a reference to a literary source in the conclusions.

• The 32% in the DG1 represent the harvest and

How were the data for Fig. 5 (in the Conclusions) obtained? The figure numbering is duplicated.

References [7]. Provide a full, correct reference to the source.

• The study was referenced in theses work

It should also be noted that the work is poorly structured and substantiated. There are critical discrepancies between the presented data and the results obtained. The presentation of data in different sections of the manuscript differs. The information is presented in a very generalized form, in vague phrases, which is not acceptable in a scientific publication. The conclusions, on the contrary, are very specific. There is no substantiation of the approach used. The numbering of sections, tables, and figures is inconsistent (for example, the sequence of sections: section 2, section 3, and immediately section 4.6; table 4.10; fig. 4.23; fig. 5 is duplicated twice). In general, the work gives the impression of disparate parts connected without logical sequence.

• Aligned all figures from result and discussion. And focus the study to the initial aim.

Reviewer 3 Report

Comments and Suggestions for Authors

1. Make sure the paper/text respects the scientific recommendations in template.
2. Title might be more coherent: Evaluation of Energy Harvesting for Economically Developing Region: A Competent Interexchange Between Energy Supply from Fossil Fuel and Renewable Energy from Photovoltaic Sources.
3. The scientific value of the paper should be reflected by the announced interexchange discussion in title.
4. Please add more keywords.
5. Abstract should not be confused with Introduction, therefore the first sentences should be eliminated and the rest ideas should be more developed to reveal the research purpose, methodology and expected results.
6. The link/study over both, energy supply from fossil fuel and renewable energy supply from solar photovoltaic is not clearly understood from provided methodology/results/conclusion, as the paper is focused on photovoltaic results, rather than other energy supply like fossil fuel.
7. Line 158 should be formated as another equation with proper numbering.
8. The figures should have appropiate/similar dimensions.
9. Trend lines equations in figures are hard to read.
10. It could be discussed further research possibilites/trends/links about hybrid PV panels/systems, in an additional section after Conclusions.
11. The paper lacks Author Contributions and Abbreviations sections.
12. More references should underline some assumptions that are presented as common knowledge, but they could be confirmed by actual scientific literature.
13. Line 459 should be deleted.
14. Overall, the ideas should a have a more logical coherency.

Comments on the Quality of English Language

1. Take care of scientific writing quality.
2. Take care of English writing quality.
3. Assure all acronyms/abbreviations are properly defined.

Author Response

Make sure the paper/text respects the scientific recommendations in template.

Title might be more coherent: Evaluation of Energy Harvesting for Economically Developing Region: A Competent Interexchange Between Energy Supply from Fossil Fuel and Renewable Energy from Photovoltaic Sources.

The scientific value of the paper should be reflected by the announced interexchange discussion in title.

More scientific word added.

Please add more keywords.

Considered some keywords

Abstract should not be confused with Introduction, therefore the first sentences should be eliminated and the rest ideas should be more developed to reveal the research purpose, methodology and expected results.

Tried to reconstruct the introduction to eliminate confusion.

The link/study over both, energy supply from fossil fuel and renewable energy supply from solar photovoltaic is not clearly understood from provided methodology/results/conclusion, as the paper is focused on photovoltaic results, rather than other energy supply like fossil fuel.

Study introduced in the introduction and alignment throughout the manuscript

Line 158 should be formated as another equation with proper numbering.

Rewrote

The figures should have appropiate/similar dimensions.

Aligned

Trend lines equations in figures are hard to read.

It could be discussed further research possibilites/trends/links about hybrid PV panels/systems, in an additional section after Conclusions.

The paper lacks Author Contributions and Abbreviations sections.

More references should underline some assumptions that are presented as common knowledge, but they could be confirmed by actual scientific literature.

Line 459 should be deleted.

Deleted

Overall, the ideas should a have a more logical coherency.

• Reconstructed

Reviewer 4 Report

Comments and Suggestions for Authors

The article discusses application of solar power technology in the region of KwaZulu Natal with the goal to replace traditionally used unsustainable energy sources such as coal. The methodology is stated to be based on multiple regression analysis applied to data obtained from a regional municipal database. The introduction describes the importance of the solar energy use in South Africa, along with the associated challenges.

I believe the topic is interesting and relevant, especially in the context of increasing environmental issues and the fact that the region in question is rich in solar energy and could greatly benefit from its use.

1) However, some of the article’s main points remain vague and the introduction includes only a small number of references.

2) In the Materials and Methods section, it would be helpful to provide a reference or link to the database used in the study.
In lines 136, 138, and 161, citations to Bewick et al. (2010), Fang (2013), and Rawski et al. (2016) are included in the text but missing from the reference list, so it is unclear what they are referring to.

3) In the Results section: line 168, Table 1 that is mentioned is actually Table 2. In line 169 the statement regarding the “other part of the world” is not correct. In line 196 the authors probably meant to refer to Table 2 and not Table 3. In line 285 a part of the sentence seems to be missing: “…good relationship among the since…”

Sentences in lines 293 and 301 are exactly the same but with 2 different references, so it is unclear what the authors wanted to say.

4) In the Discussion, lines 394–397 seem to be out of place.

Overall, the manuscript has a lot of inconsistencies in style, references, and referencing of tables and figures, with only few examples shown above. Some sections are very hard to understand and follow and could be improved. I would also expect a more detailed comparison of the results with findings from previous studies.

Comments on the Quality of English Language

The manuscript contains a lot of grammatical and stylistic errors that make it difficult to follow. Only few of the many examples are in line 27: “...load shedding”, the meaning of this part is unclear; lines 28–29: the sentence construction is confusing; line 67: the phrase is not clear; line 148 "...overlook" is misleading, etc. The manuscript requires a thorough language and grammar revision.

Author Response

1) However, some of the article’s main points remain vague and the introduction includes only a small number of references.

- Reconstructed the majority of the work

2) In the Materials and Methods section, it would be helpful to provide a reference or link to the database used in the study.

In lines 136, 138, and 161, citations to Bewick et al. (2010), Fang (2013), and Rawski et al. (2016) are included in the text but missing from the reference list, so it is unclear what they are referring to.

• Corrected

 

3) In the Results section: line 168, Table 1 that is mentioned is actually Table 2. In line 169 the statement regarding the “other part of the world” is not correct. In line 196 the authors probably meant to refer to Table 2 and not Table 3. In line 285 a part of the sentence seems to be missing: “…good relationship among the since…”

- reconstructed

Sentences in lines 293 and 301 are exactly the same but with 2 different references, so it is unclear what the authors wanted to say.

 

4) In the Discussion, lines 394–397 seem to be out of place.

- Deleted

Overall, the manuscript has a lot of inconsistencies in style, references, and referencing of tables and figures, with only few examples shown above. Some sections are very hard to understand and follow and could be improved. I would also expect a more detailed comparison of the results with findings from previous studies.

• More information has been added

 

Comments on the Quality of English Language

The manuscript contains a lot of grammatical and stylistic errors that make it difficult to follow. Only few of the many examples are in line 27: “...load shedding”, the meaning of this part is unclear; lines 28–29: the sentence construction is confusing; line 67: the phrase is not clear; line 148 "...overlook" is misleading, etc. The manuscript requires a thorough language and grammar revision.

• Some information was reconstructed and some deleted.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The quality of the article has improved, but it is still not sufficient to meet the standards of the journal. 

Author Response

File attached

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Editors and Authors!

The authors have reviewed and partially corrected the text of the manuscript (sustainability-3593681-peer-review-v2.pdf) in accordance with the previously submitted comments. At the same time, the authors ignored or responded insignificantly to most of the significant comments. I believe that without their elimination it is not possible to recommend the work for publication in the high-level journal such as Sustainability.

 

In particular, the Introduction and Conclusions have not been revised, no justification for the source of data has been provided, there are still discrepancies in the literature between the number of sources in the text and the list of references, some of the answers (for example, on the designations in the formulas) were given to the reviewer without being included in the text of the work (although this is the ultimate goal of the review), etc.

I would also like to draw the authors' attention to the use of relevant references when making corrections to the text. For example, in the text of the manuscript "The previous studies confirm that most energy is consumed in buildings with China and USA contributing 14% of the global final energy consumption through buildings [8]." (Line 127), reference [8] is the abstract of a master's thesis and contains information about "INVESTIGATING THE ROOT CAUSE OF SOLAR POWER UNSUSTAINABILITY IN KWAZULU-NATAL, SOUTH AFRICA." At the same time, this statement is not explicitly stated in the work [8].

The reviewer's work is not helped by the discrepancy between the authors' responses and the text of the revised manuscript. For example, in response to the reviewer's comment

"Line 47 and below. "The Western Cape has successfully installed solar energy with minimal failure rates"; "South African looked up to countries such Germany, America and China which have successfully installed solar energy and developed relevant technology that will promote or improve their ecological situation."; “From one South African Province to another, the comparison and implementation of solar energy has not been largely successful”; Provide references to support each of these statements."

They answer “Referenced”.

At the same time, the text of the manuscript itself does not indicate any references to these phrases.

As well as the note "Section 1 provides an introduction which has background of renewable energy, a problem statement of the study, the method used, the aims and objectives, and an overview of the significance of the study and research questions." This statement does not correspond to the content of Section 1. See the comments above.”

The authors respond, “The structure was followed and the research question was incorporated as well.” Yes, the research question was added. However, the authors did not make the changes that were originally requested, although they claim the opposite.

Etc.

 

Authors are strongly encouraged to work through all the comments presented in the initial review, make the highlighted changes to the text of the manuscript, and provide a full response to each comment indicating the corrections made. Authors are also encouraged to review the structure of publications in the latest issues of Sustainability, uniformity in numbering of tables, figures, etc.

Author Response

File with improvement attached.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The authors improved the paper, however I can't see all the improvements stated in their Response. Please be sure you upload the correct version for Final version.

Author Response

File with improvement attached

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

I have no further science-related comments.

Comments on the Quality of English Language

I strongly recommend that the authors have the manuscript reviewed by a professional English editing service as it still contains a lot of stylistic and language issues that may affect understanding of the text.

Author Response

File attached with changes

Author Response File: Author Response.docx

Round 3

Reviewer 1 Report

Comments and Suggestions for Authors

This article is highly applicable and offers practical reference value.

The authors have made the required revisions, and I agree to accept it in its current form.

Author Response

«Weak» Introduction. The essence of the issue considered in the article is not sufficiently substantiated. There is practically no argumentation as to why this is important. The authors do not indicate the current state of the issue, confirmed by the relevant literature references. What studies have been conducted in this area, etc. It would also be useful to include an image of the region that the authors are studying.

- literature What it says: [1] believes that KZN citizens can be rescued by the use of renewable Energy instead of coal energy  to avoid fossil fuel disastrous consequences. While [2] noticed that three KZN solar irradiation data sets for Kwazulu-Natal on average decreases in size by 3 kW of PV panels.  During the KZN case study done by [1] the PV system is one of clearness and environment friendly technology for the production of electricity. Refer to line 84 -89.

Please clearly justify the relevance of the problem, indicate the purpose of the work, its novelty, the general and specific contribution of this work, where the results obtained are applicable.

• Argument and novelty of the work: Improve solar implementation in low developing regions such as KZN for small scale businesses using multiple regression and solar system analysis for planning and managing the system in the small scale. [1] cited that energy production through environmental data is the major component on solar PV systems.  Most studies look at the broader view of the country. If KZN region (eThekwini municipality) is measured based on the amount of sunlight it receives it will be easy to plan for interchanging from fossil fuel to solar energy. [1] believes that it is vital to understand amount of solar for the location in order to design solar PV. The high demand of development of sustainable renewable energy balance requires more contributions to RE understanding. is due to a growing understanding of how RE contributes to the development of a more sustainable energy consumption balance [3]. Refer to line 96 -106.

Line 42. "The South African government has supported the promotion of renewable energy throughout the globe such as China." Provide a link confirming this statement.

• Reference this statement: “The South African government has supported the promotion of renewable energy throughout the globe but focused on the techniques implemented by developed countries such as China [4]”

Line 47 and below. "The Western Cape has successfully installed solar energy with minimal failure rates"; «South African looked up to countries such Germany, America and China which have successfully installed solar energy and developed relevant technology that will promote or improve their ecological situation.»; «From one South African Province to another, the comparison and implementation of solar energy has not been largely successful»; Provide references to support each of these statements.

• Added a supporting referenced – From which the statement the literature comes from: The Western Cape province (Cape Town) represents approximately 25 % of beverage production and has irradiation during in dry summers and hot weather regardless of its location. Some researchers believes that KZN province is one of the low irradiation and make it low on beverage production by at least 10 % [4]. Refer to line 64 – 70

Line 57. «Several solar energy harvesters have been installed in KZN; however, the failure rate have consistently gone downward through the infrastructure and technological installation».

• references needed: SA’s primary biomass resources are in KZN but also in Mpumalanga and Limpopo [1]. Refer to line 83.

Line 61. «The study intends to demonstrate solar PV adaptable in the region of KZN as [4] Believes that Photovoltaic system is one of the profitable systems without storage technology.» It is not clear what the reference [4] refers to.

• The sentence was reconstructed, and the word spending was missing: without spending more on the storage technologies. (the term spending was missing on the sentence). Refer to line 91 – 93.

Line 467 and below. «Use full justification … (pp. 1-4)». How is this text related to the Introduction? Please justify in the text of the article what these statements are and how they relate to the authors' research. If necessary, provide references to the source(s).

• The text was removed from the manuscript since it was not related.

Line 78. "Section 1 provides an introduction which has background of renewable energy, a problem statement of the study, the method used, the aims and objectives, and an overview of the significance of the study and research questions". This statement does not correspond to the content of Section 1. See the comments above.

• As section 1 introduced the study (through reading you will discover: introduction, background, problem statement, aim and objective, research questions and summary of the article)

Line 98. "Data utilized in this study on solar energy was extracted from the database of regional municipality under the department of renewable energy". Please provide more detailed information about "regional municipality" and "department of renewable energy" and the data obtained. Provide an appropriate reference to the source of the data. If this is classified information, do the authors have the right to use the obtained data for processing and presentation?

• eThekwini municipality is regional municipality with a special department of renewable energy office that focuses on collecting KZN energy data, focusing in solar energy mostly.

Line 102. And below. "3.1 Sample and population". Provide more specific information in this section. (number, placement, size, time range, etc.)

• The section is 2.1 Sample and population: It modified to: “The target of the population for this study was the directly involved users of regional municipality solar power projects developed in the past decade which are available in the regional municipality database. The installed solar system within eThekwini region of 50 site and of 20m² size plot each site. The data was for the period of 5 years from 2015 to 2020. Due to the high number of variables, this study will focus on the high impact variables that led to multiple regression. The database has multiple buildings that installed solar power which was used to apply these variables (solar harvested, and consumption). The regional municipal historic solar energy for these buildings was utilized to conduct comparison between the variables. The previous studies confirm that most energy is consumed in buildings with China and USA contributing 14% from the global final energy consumption through buildings [11]” refer to line 146 – 157.

Line 125. "Multiple regression analysis is the most suitable regression approach since it is a statistical technique that mostly analyses the relationship between a single dependent variable and several independent variables." Provide a reference to support this statement.

• Referenced

Line 131. "if the value p". Specify what the value "p" means.

• It p-value where p represents probability

Line 136. And further in the text "for example, (Bewick et al., 2010), Rawski et al., (2016)" etc. Use a uniform approach to indicate references (square brackets).

• Journal uniform -The references were replaced with latest reference, but I have maintained the uniform: refer

There is a discrepancy between the references (14) and their citations in the text (e.g., [15 & 16], (Bewick et al., 2010), (Fang, 2013), Rawski et al., (2016), etc.). Please, align the number of references and their citations in the text.

• Replaced within new references. – This has been fixed reference properly

Line 133. Specify what the value of " ε" in the formula means. If this is the formula used by the authors, then provide a link to the source or indicate that this is the author's approach.

• The means error – provide the reference

How do the equations in lines 133 and 139 differ from each other? Justify why this particular form of regression dependence was chosen in this work. Provide references if necessary.

• There is nothing differ from these equations. The two equations emerged to one and variables were detailed. The final equation is:   
• Where:
• Y0 is the dependent variable (overall output)
• x: independent variable (input)
• a: intercept (Y value at x = 0)
• b: gradient of the regression line
• ε: accidental error.

The designations of the elements of equation (1) are incorrect. In the equation, they have indices, while in the explanation there are no indices.

•  Indices are included on the explanation

Y₀ is the dependent variable (overall output)

: independent variable (input)

a: intercept (Y value at x = 0)

: gradient of the regression line (it the same throughout)

ε: accidental error.

 

Line 147 «Decisions are influenced by the results obtained from the analysis including the regression results.»; « To improve the status, it is necessary to overlook the cause of failure or possible causes of failure.» Provide references to support each of these statements. What «Decisions» are the authors talking about? Provide a more detailed description

• Reference to the regression analysis as they are influenced by the difference studies. More description is given on the paragraph – decision regarding

Line 151. «The coefficient of determination…». Where is this coefficient and its designation given?

• To validate the regression result, The coefficient of determination is introduced in this line and values are given on the results and discussion. Validating the study equation:

Data validation equation

The mathematical coefficient formula used in this research is:

r² = [Σ(xy)- (Σx)(Σy)/n))/√(Σx² -(Σx²/n)(Σy²-(Σy²/n))]² = variation explained by regression/total variation.

Where:

n= number approach

x= variables

y=solar system production

Line 158. If this is the formula used by the authors, then provide a link to the source or indicate that this is the authors' approach. Provide the designations of all elements used in the equation. How do these elements correlate with formula (1)

• Designation is also included in the study – Double check if the formular is there,
• r² = [Σ(xy)- (Σx)(Σy)/n))/√(Σx² -(Σx²/n)(Σy²-(Σy²/n))]² = variation explained by regression/total variation.
• Where:
• n= number approach
• x= variables
• y=solar system production

Use a unified approach to designate the same quantities (e.g., r² and R2, V0 and V_0, x1 and X1, P and p, etc.).

• Uniform applied

Line 165 and below. The authors do not provide any references to the temperature data obtained. In some places, the designation 0C is missing, and the statement "This is the coldest period of the KwaZulu Natal region as well as other part of the world" is also unfounded.

• Referenced temperature and restructure based on the winter.
• represents dependent variable (solar power production), and x indicates independent variables (e.g. solar power consumption, Temperature (℃)).

The logical structure of the article is broken, for example, in "3. Results" the authors discuss "group 2" without explanation, and then below, in Table 2, provides an idea of what exactly is being divided into groups, the authors use formula (1), where x1, x2, x3 are indicated, whereas further in the work, in Table 1, x1, x2, x3, x4, x5 are already used.

• The equation and the table has the same equation with equally number of variables.

Line 174. "x indicate independent variable (e.g. solar power consumption, Temperature)." This statement does not correlate with the text in Section 2 and in Table 1.

• Solar variables are represented by x and all are align the variable

Line 178. "The variables presented in Table 1 above were obtained from the database of eThekwini Municipality". Table 1 does not provide any data. It is not clear whether the authors use data only from eThekwini Municipality or for the entire region of KwaZulu Natal, as stated in the text of the article.

• Reconstructed the sentence. Re-aligned: The data used all comes from eThekwini region on the database of renewable office. The information is for Solar energy harvested and solar energy consumed.

Line 179. "The temperature, period and solar radiation were collected directly from the renewable energy as well as in the historical information." This statement does not correlate with the text given in Section 2 and Table 1. The dimensions of these quantities also do not correlate with the dimensions presented in Table 1. If these are different data,

• The statement was removed because it was contradicting, and it was presented on section 2.1 under sample and population.

Line 195. "The solar power grouped using categories months in the table 3." does not correlate with the contents of Table 3 "Table 3: Independent variable significance indication"

• Aligned with the table 3 to fit the data group

Line 197. "The solar system parameter, which is the dependent variable are investigated throughout all independent variable (consumption, solar import, energy export, solar self-consumption and temperature)." does not correlate with the parameters of Table 2.

• Table 2 provides the Data grouping (DG) information, this line also take information on table 1.

Lines 197-204. It is not clear from the text of the article whether temperature is a parameter under consideration or not

• Temperature is the guiding value to the data grouping provided in table 2.

It is not clear how the data (and what they represent) were obtained in Fig. 1-16. Table 2 only gives an idea of the breakdown of the data into groups. What kind of data this is, how they correlate with each other over time or in any other way is not clear from the text of the manuscript. Why they are presented in this form in Fig. 1-4, 5-8, 9-12, 13-16 is not clear.

• Data was grouped in the seasonal grouping to analyse and avoid confusion. All the statistical and presented in the graph.

Line 331. "The reason for outlining data grouping throughout the is to demonstrate the performance among the parameters during the different season and weather conditions." How did the authors track the change in weather conditions over time? Or is this data for only one year? Can other factors influence these parameters and why? The authors do not discuss this in the transcript.

• We tool information from the department of renewable and used the statistical for one year and predicted data was validated

It is not clear how the data in Table 3 were obtained.

• Re-introduced on the paragraph: The historical data was applied on the multiple regression to be able to analysis the future performance of the solar system. Table 3 is the statical summary of all variables. It was obtained on the excel through multiple regression analysis

It is not clear how the authors move from regression analysis (section 3.1-3.2) to multiple regression model (section 4.6)

• Due to number of variable the most useful equation is for multiple regression that will be inline with linear overview.

Line 351. "In summary, the table 4.10 below demonstrate the following that". Table 4.10 is missing from the text.

• The statement was aligned with following table 5

Overall, section "4.6 APPLICATION OF MULTIPLE REGRESSION MODEL" seems to be taken out of context. There is no justification for the applicability of the model, no explanation of what the parameters in tables 3-5 are, how these coefficients were obtained, if above (section 3.1, 3.2) the authors spoke about linear regression. The discussions that are carried out in this section come before section 4 "Discussion", which also does not correspond to the logic of the article.

Explanation: The use of multiple regression can lead to the better understanding of decision-making for economical reason to make improvement on the systems.  

It is not clear how the coefficients of table 4 were obtained, which are then used in "the projected model " in the "Discussion" (line 378).

• Introduce the table for better understanding of the ecoefficiency.

Line 389. Perhaps a formula (table) is missing?

• Formular inserted: same equation: Yv= 42603,780 + 0,0136x₁ + 0,4425x₂+ 0,1667x₃ + 0,1554x₄ +0.011x₅ + ε

The conclusions contain a conclusion on the results of the study. On what basis did the authors include the figure?!

• The graph is included on the base of validating the recommendation on solar implementation in eThekwini region. This help reader to understand the predictions made from the results.

Line 416. "Solar power production (Wh) in the DG 1 shows an almost 32% of solar power to be produced in this term ." It is not clear why the authors use a reference to a literary source in the conclusions.

• The references were removed as this comes directly form the results. The 32% in the DG1 represent the harvest and

How were the data for Fig. 5 (in the Conclusions) obtained? The figure numbering is duplicated.

References [7]. Provide a full, correct reference to the source.

• Full representation of reference: N. Mdlolo, “Investigating the Root Cause of Solar Power Unsustainability in Kwazulu-Natal, South Africa,” no. November, 2019.

 

It should also be noted that the work is poorly structured and substantiated. There are critical discrepancies between the presented data and the results obtained. The presentation of data in different sections of the manuscript differs. The information is presented in a very generalized form, in vague phrases, which is not acceptable in a scientific publication. The conclusions, on the contrary, are very specific. There is no substantiation of the approach used. The numbering of sections, tables, and figures is inconsistent (for example, the sequence of sections: section 2, section 3, and immediately section 4.6; table 4.10; fig. 4.23; fig. 5 is duplicated twice). In general, the work gives the impression of disparate parts connected without logical sequence.

• Aligned all figures from result and discussion. And focus the study to the initial aim.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Editors and Authors!

The review of the submitted manuscript revealed some edits that, in essence, do not significantly improve the quality of the manuscript. Authors often do not respond to the reviewer's comments, the answer does not correspond to the essence of the question or does not correspond to what is actually written ("corrected / not corrected") in the manuscript.

For example,

“Please clearly justify the relevance of the problem, indicate the purpose of the work, its novelty, the general and specific contribution of this work, where the results obtained are applicable”

The authors respond

“Aligned accordingly, refer to line 59 to 60. “ (!)

These lines lack the required corrections, as do the text of the Introduction.

 

Or

 

“Line 67 and below. “Use full justification … (pp. 1-4)”. How is this text related to the Introduction? Please justify in the text of the article what these statements are and how they relate to the authors' research. If necessary, provide references to the source(s).”

The authors respond

“The text was removed from the manuscript since it was not related.”

 

Whereas in fact

Line 97 “Useful justification:

1. The energy interchanging to solar PV system can be used in the high solar radiant such as KZN region to provide clean energy.
2. Solar PV system is continuously improved and protective of the environment.
3. The cost of the solar PV system is very affordable, and it is profitable, which forces the interchange to be supported.
4. The sufficient energy efficient to be produced by the solar PV system in the 103 eThekwini region is proven by the regression analysis to determine

a) Risks of interchanging to implementing solar PV at high rate

b) Failure rate of the system

c) Cost related to the implementation of solar PV system.”

And etc.

 

As a general remark, it should be noted that references to correction lines do not improve the quality of the answer, since the lines have apparently shifted and do not correspond to the essence of the question, the literature in the text does not match the number of literature in the List of References (there are no references to sources 23 and 24), there are punctuation errors, changes in the case of characters, etc. This also worsens the perception of the manuscript.

I would also like to note the lack of structure of the manuscript. In particular,

Line 90 and further "The research questions that the article will focus on: 1. What diverse KZN region from being the leading solar energy implement? 2. Is solar harvest in the region of KZN favorable or easily affected by the moisture? 3. Based on the scarcity of skill to implement a successful solar rate, what majorly can be in place to control solar energy failure rate? Thus, the research is focused on the PV technology implementation in KZN region". Further, these questions are not reflected in the Conclusions.

 

The Conclusions themselves contain figures, although the previous remark noted the need for their absence. The authors' conclusions are essentially a continuation of the discussion.

Authors are encouraged to study the latest issues of the journal to familiarize themselves with the journal's accepted article structure.

 

It is recommended that the manuscript be carefully revised, taking into account the previous ( and these comments, before submitting it for re-review.

Author Response

Attached

Author Response File: Author Response.docx