Decoding Solar Adoption: A Systematic Review of Theories and Factors of Photovoltaic Technology Adoption in Households of Developing Countries

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. The introduction briefly mentions the research gap but lacks a clear articulation of the novelty of the study. It would be beneficial to explicitly highlight how this study differs from previous research.
2. The objective of the study is not clearly stated in the abstract. Consider revising the abstract to include a concise and clear statement of the study's primary objective.
3. The methodology section lacks a clear justification for the selected methods. It is recommended to provide a rationale for the chosen methods and experimental setup.
4. The literature review section provides a good background but lacks recent references from the past two years. Including more up-to-date references would strengthen the study.
5. The results section provides raw data without a detailed interpretation. It is suggested to provide a more in-depth discussion about the implications of the results.
6. Statistical Analysis:It would be beneficial to include a statistical analysis to validate the experimental results and improve the credibility of the findings.
7. Figures and Graphs:Several figures are presented without proper captions or descriptions. Each figure should have a clear and informative caption, along with a brief interpretation in the text.
8. Unit Consistency:The units used in the results section are inconsistent. It is recommended to standardize the units throughout the document.
9. Comparison with Existing Work:The discussion section lacks a comparison of the study's results with those from similar studies. Adding a comparative analysis would enhance the credibility of the findings.
10. Conclusions Section:The conclusion section is too brief and does not summarize the key findings effectively. It is recommended to expand the conclusion with key insights, practical implications, and future directions.
11. Conclusions Section:It is recommended to elaborate on the potential real-world applications of your findings and provide more specific future research directions. This will help readers understand the broader impact and potential scope of your work.
12. Conclusions Section:Consider adding a comparative analysis with existing literature, particularly emphasizing how your findings align or differ from those in similar studies. This will enhance the scientific impact and validity of your research.
13. Figure 1:The quality of Figure 1 is poor, making it difficult to interpret the data. It is suggested to provide a high-resolution image.
14. Page 5, Table 2:The table does not have a footnote explaining the abbreviations used. Adding a footnote would improve the readability of the table.
15. The section3 lacks a comprehensive comparison of the most commonly used theoretical frameworks. Consider including a brief comparison table or diagram to highlight the key differences and applicability of each framework in understanding consumer behavior.
16. Section3；The discussion does not provide recent references to support the theoretical frameworks. It is recommended to include recent literature (preferably within the last five years) to strengthen the academic foundation of this section.
17. References Section:Several references are outdated (older than 10 years). It is highly recommended to update the references to include recent studies to improve the relevance of the literature review. Most recent literature is missing org/10.1016/j.renene.2024.121834, doi.org/10.1016/j.energy.2024.131802
18. Section 4.4: Link the technological findings to specific policy implications, such as regulatory frameworks or sustainability policies, to enhance the practical relevance of the study.

Comments on the Quality of English Language

 The English could be improved

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

1. The introduction briefly mentions the research gap but lacks a clear articulation of the novelty of the study. It would be beneficial to explicitly highlight how this study differs from previous research.

The currents lines were included in the introduction to address this comment: However, the adoption of household PV in developing countries still lags behind that in developed nations. Unique socioeconomic, infrastructural, and cultural factors in developing economies can hinder or facilitate adoption in ways not fully captured by models based on developed-country contexts. There is a need to decode solar adoption by examining the theories and factors that have been studied in relation to household PV uptake in developing countries. This study differentiates itself from prior reviews by focusing exclusively on behavioral theories applied to household PV adoption in developing countries, emphasizing context-specific socioeconomic and policy variables often neglected in global analyses. (Lines 41-49)

2. The objective of the study is not clearly stated in the abstract. Consider revising the abstract to include a concise and clear statement of the study's primary objective.

The beginning of the text in the abstract was modified to address the comment with this sentence: This systematic review explores key theories and factors shaping the adoption of photovoltaic (PV) systems by households in developing countries. Following the PRISMA protocol, we re-viewed 44 empirical and theoretical studies published between 2010 and 2024, selected from an initial set of 350 articles retrieved from Scopus and Web of Science. (Lines 11-14)

3. The methodology section lacks a clear justification for the selected methods. It is recommended to provide a rationale for the chosen methods and experimental setup.

The following sentences were included to address this comment: A qualitative synthesis was chosen due to the methodological heterogeneity of included studies, which range from case studies to quantitative models, making meta-analysis unfeasible. This method allows for thematic exploration across diverse contexts. (Lines 95-97)

4. The literature review section provides a good background but lacks recent references from the past two years. Including more up-to-date references would strengthen the study.

Currently, 18 references were obtained from the application of the bibliographic review equation, which are part of publications from the last two years. If some recent researches were excluded after the search process using the equation, it was because they did not meet the screening criteria during the selection of the final documents for full review.

5. The results section provides raw data without a detailed interpretation. It is suggested to provide a more in-depth discussion about the implications of the results.

Two paragraphs were modified to address this comment: The results of this review show the variation in theoretical framework, factor and methodology applied in the studies of household PV in developing countries. Consumer decision-making theories like the TPB, TAM and DOI framework have widely been applied to explore consumer decision-making processes. Their use in developing contexts comes with limitations, though. Analysis fails to consider the specific socio-economic, infrastructural, and policy environments that impact consumer habits in these regions, often this leads to the application of models developed for high income nations with insufficient context. Research in this field should therefore pursue the endeavor of refining these constructs or come up with new models to capture the realities related to energy access and affordability constraints in developing countries. (Lines 433-442)

A key gap in the literature noted is the lack of integration between behavioral economics and psychological insights with respect to the study of PV adoption. Alt-hough economic factors like cost, subsidies and the return on investment are some-times widely cited, less research focuses on consumer decision processes in relation to cognitive biases, risk perceptions and decision heuristics. These are psychological concepts whose understanding would offer insights on how households trade long-term energy security against short-term financial pressure. Furthermore, alt-hough some studies consider elements like social norms and community influence, their role in helping to explain large-scale adoption trends remains under-explored. (Lines 443-451)

6. Statistical Analysis: It would be beneficial to include a statistical analysis to validate the experimental results and improve the credibility of the findings.

We acknowledge the reviewer’s suggestion to incorporate a statistical analysis; however, this was not appropriate for the present review due to the substantial methodological heterogeneity among the included studies. The selected literature comprises a wide range of empirical designs-qualitative case studies, quantitative surveys, mixed-method evaluations, and theoretical modeling-which differ in both scope and variables measured. As such, applying a meta-analytic technique or statistical aggregation would have required the exclusion of many studies, potentially introducing selection bias and reducing the comprehensiveness of the synthesis.

7. Figures and Graphs: Several figures are presented without proper captions or descriptions. Each figure should have a clear and informative caption, along with a brief interpretation in the text.

The caption in figure 2 was included to address the comment. It was included according to the journal style recommendations: The keyword co-occurrence network highlight’s central themes like developing countries and solar energy, with clusters focusing on policy, technical aspects, rural electrification, and sustainability. Strong connections, such as between renewable energy and energy policy, emphasize governance's role, while gaps in areas like technology diffusion suggest opportunities for further research. (Adjusted caption for Figure 2)

It is worth noting that the paragraph in the document after figure 2 was also included to explain further the results of the graph.

8. Unit Consistency: The units used in the results section are inconsistent. It is recommended to standardize the units throughout the document.

Units and subunits have been adjusted to make them consistent across the article.

9. Comparison with Existing Work: The discussion section lacks a comparison of the study's results with those from similar studies. Adding a comparative analysis would enhance the credibility of the findings.

The discussion section was complemented and included with the next paragraph to address this comment: Nonetheless, within the current body of literature, some clear insights emerge. Financial barriers – especially high upfront installation costs and limited access to credit – are consistently cited as the primary obstacle to household PV adoption in developing countries (appearing in the majority of studies). Information and awareness gaps also loom large; where knowledge about solar benefits and technical know-how is lacking, adoption lags. On the positive side, peer effects and community success stories can strongly encourage adoption, suggesting that pilot projects and demonstration homes can have a multiplier effect if well publicized. Policy support (subsidies, feed-in tariffs, or net metering) has been shown to be a game-changer in several contexts, but policies need to be stable and effectively communicated to build trust. Importantly, the review underscores that models and frameworks must be context-sensitive: for instance, TAM and TPB can be useful, but they may require additional factors (like trust in providers, or perceived risk of technology failure) to fully explain behavior in low-income, infrastructure-poor settings. (Lines 482-495)

10. Conclusions Section: The conclusion section is too brief and does not summarize the key findings effectively. It is recommended to expand the conclusion with key insights, practical implications, and future directions.

The conclusion section was complemented and included with the next paragraph to address this comment: Overall, these gaps and patterns call for a more nuanced approach in both re-search and practice. Future research should aim to bridge the identified gaps. This includes integrating behavioral economics perspectives (to understand decision-making under poverty and uncertainty), exploring under-studied regions, and examining long-term adoption dynamics (not just intention or early adoption, but sustained use and expansion of PV systems). For practitioners and policy-makers, the findings imply that successful promotion of household solar in developing countries must tackle fi-nancial barriers (through subsidies or innovative financing like pay-as-you-go schemes), invest in community engagement and education, and ensure after-sales support to build confidence in the technology. (Lines 498-506)

11. Conclusions Section: It is recommended to elaborate on the potential real-world applications of your findings and provide more specific future research directions. This will help readers understand the broader impact and potential scope of your work.

The conclusion section was complemented and included with the next paragraph to address this comment: Such efforts to address the gaps in knowledge and practice are crucial for ad-vancing the field. By developing appropriate policies, business models, and community interventions that are tailored to local contexts, stakeholders can promote the adoption of PV technology in the developing world-helping to achieve broader sustainability and energy access goals. In conclusion, while significant progress has been made in understanding household PV adoption in emerging economies, there remains much to learn. This systematic review provides a foundation and direction for future work aimed at decoding and accelerating solar adoption where it is needed most. (Lines 511-518)

12. Conclusions Section:Consider adding a comparative analysis with existing literature, particularly emphasizing how your findings align or differ from those in similar studies. This will enhance the scientific impact and validity of your research.

The discussion section was complemented and included with the next paragraph mentioned in comment number 9 to address the recommendation in this comment.

13. Figure 1:The quality of Figure 1 is poor, making it difficult to interpret the data. It is suggested to provide a high-resolution image.

To address this recommendation, Figure 1 was improved according to journal requirements and was generated inside the word document to improve the legibility and resolution.

14. Page 5, Table 2: The table does not have a footnote explaining the abbreviations used. Adding a footnote would improve the readability of the table.

To address this suggestion, abbreviations were included in Table 1 and are in parenthesis in Table 2, first column.

15. The section 3 lacks a comprehensive comparison of the most commonly used theoretical frameworks. Consider including a brief comparison table or diagram to highlight the key differences and applicability of each framework in understanding consumer behavior.

To address this comment, the main discoveries and theoretical frameworks used by the main authors and publications were included in Table B1.

16. Section 3；The discussion does not provide recent references to support the theoretical frameworks. It is recommended to include recent literature (preferably within the last five years) to strengthen the academic foundation of this section.

In response, we carefully reviewed the citations in this section and confirmed that several references published within the last five years (2020–2024). Some recent sources were used to update and support the application of the Technology Acceptance Model (TAM), the Theory of Planned Behavior (TPB), and other frameworks in the context of developing countries. (e.g. works such as Kyere et al. 2023, Waris et al. 2022, and Duque-Hurtado & Duque 2024)

17. References Section: Several references are outdated (older than 10 years). It is highly recommended to update the references to include recent studies to improve the relevance of the literature review. Most recent literature is missing.

Some references included in the manuscript were published more than ten years ago. However, these sources were retained intentionally due to their foundational contribution to the theoretical frameworks and empirical constructs analyzed in this review. Additionally, the selected time window for this systematic review -2010 to 2024- was defined with methodological purpose. It begins shortly before the global adoption of the Sustainable Development Goals (SDGs) in 2015, which marked a shift in international energy and development agendas and extends to include the most current publications available at the time of writing. This window allows us to examine how PV adoption research in developing countries evolved both before and after the SDG framework, particularly SDG 7 (Affordable and Clean Energy). Within this timeframe, we ensured that recent and relevant studies were well represented. In fact, 18 of the 44 studies included were published within the last two years (2022–2024)

18. Section 4.4: Link the technological findings to specific policy implications, such as regulatory frameworks or sustainability policies, to enhance the practical relevance of the study.

To address this recommendation a last paragraph was included at the end of section 4.4. section:  These findings have significant implications for policy and regulatory frame-works. For instance, the documented importance of trust in providers and the availability of after-sales support highlights the need for national regulations that enforce service quality standards and consumer protection mechanisms (Alrashoud & Tokimatsu, 2019). Governments and regulatory agencies could establish technical certification schemes for PV installers, minimum warranty periods, and independent grievance redress systems to foster trust and ensure technological reliability (Wang et al., 2023). Moreover, the identification of maintenance and reliability issues as key adoption barriers suggests that public programs should not only focus on upfront subsidies, but also on sustained technical support and training (Ahmed et al., 2022). (Lines 422-431)

Comments on the Quality of English Language

The English could be improved.

We appreciate the reviewer’s observation regarding the use of English. In response, we conducted a careful and systematic language revision throughout the manuscript. This included improvements in grammar, word choice, sentence structure, and overall writing style. The revised version aims to enhance clarity, coherence, and academic tone, ensuring that the arguments are communicated with greater precision and fluency. We are confident that these changes significantly improve the readability and linguistic quality of the manuscript.

We sincerely thank the reviewer for their careful and constructive feedback, which has been invaluable in strengthening the overall quality of the paper.

Reviewer 2 Report

Comments and Suggestions for Authors

1) The text could be more concise and summarize the theoretical and empirical fundamentals. Some sections, like the discussion of frameworks, could be simplified for better clarity.

2) The discussion is informative, however it could benefit from an evaluation of the gaps and limitations, especially with respect to geographic imbalances and the absence of behavioral economics integration. The concept of a developing country is currently broad and unspecific. Thus, it would be more accurate if the authors could define the World Regions targeted such as Latin America, Africa, the Middle East, and the Far East, and classify the target countries by the Human Development Index (HDI).

3) Figure 1 is confusing, and needs to be improved to be better understood.

4) The Figure 2 is presented twice.

5) The conclusions are based on the review findings, further emphasis on actions and more connections to the evidence base would strengthen this section.

Comments on the Quality of English Language

The language is clear and professional, but could be more objective and eliminate small redundancies.

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

1) The text could be more concise and summarize the theoretical and empirical fundamentals. Some sections, like the discussion of frameworks, could be simplified for better clarity.

To address this recommendation, we revised Sections 3.1 through 3.4 to streamline the language, remove redundant phrasing, and improve the logical flow. While maintaining the theoretical rigor of the analysis, we ensured that each framework’s relevance and limitations in the context of developing countries are clearly and efficiently conveyed.

2) The discussion is informative, however it could benefit from an evaluation of the gaps and limitations, especially with respect to geographic imbalances and the absence of behavioral economics integration. The concept of a developing country is currently broad and unspecific. Thus, it would be more accurate if the authors could define the World Regions targeted such as Latin America, Africa, the Middle East, and the Far East, and classify the target countries by the Human Development Index (HDI).

To address the recommendation, these two paragraphs were included: Nonetheless, within the current body of literature, some clear insights emerge. Financial barriers – especially high upfront installation costs and limited access to credit – are consistently cited as the primary obstacle to household PV adoption in developing countries (appearing in the majority of studies). Information and awareness gaps also loom large; where knowledge about solar benefits and technical know-how is lacking, adoption lags. On the positive side, peer effects and community success stories can strongly encourage adoption, suggesting that pilot projects and demonstration homes can have a multiplier effect if well publicized. Policy support (subsidies, feed-in tariffs, or net metering) has been shown to be a game-changer in several contexts, but policies need to be stable and effectively communicated to build trust. Importantly, the review underscores that models and frameworks must be context-sensitive: for in-stance, TAM and TPB can be useful, but they may require additional factors (like trust in providers, or perceived risk of technology failure) to fully explain behavior in low-income, infrastructure-poor settings. (Lines 482-497)

Overall, these gaps and patterns call for a more nuanced approach in both re-search and practice. Future research should aim to bridge the identified gaps. This in-cludes integrating behavioral economics perspectives (to understand decision-making under poverty and uncertainty), exploring under-studied regions, and examining long-term adoption dynamics (not just intention or early adoption, but sustained use and expansion of PV systems). For practitioners and policy-makers, the findings imply that successful promotion of household solar in developing countries must tackle financial barriers (through subsidies or innovative financing like pay-as-you-go schemes), invest in community engagement and education, and ensure after-sales support to build confidence in the technology. (Lines 498-510)

3) Figure 1 is confusing and needs to be improved to be better understood.

To address this recommendation, Figure 1 was improved according to journal requirements and was generated inside the word document to improve the legibility and resolution.

4) The Figure 2 is presented twice.

One of the repeated figures has been deleted.

5) The conclusions are based on the review findings, further emphasis on actions and more connections to the evidence base would strengthen this section.

To address the recommendation, these three paragraphs were included: Such efforts to address the gaps in knowledge and practice are crucial for advancing the field. By developing appropriate policies, business models, and community interventions that are tailored to local contexts, stakeholders can promote the adoption of PV technology in the developing world-helping to achieve broader sustainability and energy access goals. In conclusion, while significant progress has been made in understanding household PV adoption in emerging economies, there remains much to learn. This systematic review provides a foundation and direction for future work aimed at decoding and accelerating solar adoption where it is needed most. (Lines 511-518)

The language is clear and professional but could be more objective and eliminate small redundancies.

We appreciate the reviewer’s observation regarding the use of English. In response, we conducted a careful and systematic language revision throughout the manuscript. This included improvements in grammar, word choice, sentence structure, and overall writing style. The revised version aims to enhance clarity, coherence, and academic tone, ensuring that the arguments are communicated with greater precision and fluency. We are confident that these changes significantly improve the readability and linguistic quality of the manuscript.

We sincerely thank the reviewer for their careful and constructive feedback, which has been invaluable in strengthening the overall quality of the paper.

Reviewer 3 Report

Comments and Suggestions for Authors

The study is interesting and provides a useful contribution to the operators/studies of the sector.
However, it has several limitations, the most important of which are perfectly explained by the authors, and this is certainly a note of merit of the article.

The main limitations in my opinion are:

1. The analysis does not consider the specific socio-economic, infrastructural and political contexts that influence consumer habits in developing countries, often leading to the application of models developed for high-income nations. Research should therefore pursue the objective of refining these constructs or developing new models to capture the realities related to energy access and affordability constraints in developing countries.
2.  Fundamental aspects related to costs, subsidies and return on investment, and others such as bureaucracy, time, installation hassle, market complexity, all aspects aimed at understanding how households balance long-term energy security with short-term financial pressure, are not sufficiently considered. households balance long-term energy security with short-term financial pressure. The authors themselves underline how financial barriers, in particular high initial installation costs and limited access to credit, are consistently cited as the main obstacle to the adoption of domestic photovoltaics in developing countries.
   In this context, a reference to the "Transaction Cost Theory" could be useful.
3. There is a problem - also clearly underlined by the authors - linked to the strong geographical imbalance of the studies considered, concentrated in Asia to the detriment of other areas.                                                                                                                                 

I therefore believe that the main elements to improve the paper are already fully available to the authors, given their awareness of the matter.
I would add that, perhaps, the time limit 2010-2024 could be extended, to try to identify more relevant articles, as well as it is worth asking whether to limit the search to WoS and Scopus.
Finally, I think that an explicit reference to the concept of "sustainability", already in the abstract, is useful to connect the paper to the typical topics covered by the journal.

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

The main limitations in my opinion are:

1. The analysis does not consider the specific socio-economic, infrastructural and political contexts that influence consumer habits in developing countries, often leading to the application of models developed for high-income nations. Research should therefore pursue the objective of refining these constructs or developing new models to capture the realities related to energy access and affordability constraints in developing countries.

To address this suggestion the following were completed and included in the text: However, most of these models were originally developed in high-income contexts, and their uncritical application to developing countries may fail to capture the complexities associated with energy poverty, informal economies, and fragile institutions. (Lines 495-497)

And: To address these challenges, future theoretical work should prioritize the development of flexible, adaptive models grounded in the realities of developing regions. This includes incorporating multidimensional poverty, informal housing structures, and non-linear adoption dynamics. (Lines 507-510)

However, we note that the main objective of this systematic review is not to develop new theoretical models, but rather to synthesize and critically evaluate the behavioral theories and empirical factors that have been applied in the study of residential PV adoption in developing countries. Thereby providing a conceptual map that can inform future research and model development efforts.

2. Fundamental aspects related to costs, subsidies and return on investment, and others such as bureaucracy, time, installation hassle, market complexity, all aspects aimed at understanding how households balance long-term energy security with short-term financial pressure, are not sufficiently considered. households balance long-term energy security with short-term financial pressure. The authors themselves underline how financial barriers, in particular high initial installation costs and limited access to credit, are consistently cited as the main obstacle to the adoption of domestic photovoltaics in developing countries.

In this context, a reference to the "Transaction Cost Theory" could be useful.

Although the majority of studies applied consumer behavior models, no studies explicitly integrated transaction cost elements such as time, complexity, or procedural burden—highlighting a theoretical blind spot. (Lines 218-220)

And: Notably, none of the studies integrated Transaction Cost Theory, despite its relevance for capturing institutional inefficiencies and hidden costs associated with decentralized energy technologies. (Lines 324-326)

3. There is a problem - also clearly underlined by the authors - linked to the strong geographical imbalance of the studies considered, concentrated in Asia to the detriment of other areas.

In response to this suggestion, we have added: Mostly, studies revealed a regional imbalance, with more than 60% focusing on Asia, while Latin America and the Middle East were underrepresented. (Lines 453-455)

And: A more balanced regional representation in future empirical research would enhance the development of culturally and institutionally relevant PV adoption strategies. (Lines 457-459)

• I therefore believe that the main elements to improve the paper are already fully available to the authors, given their awareness of the matter.
• I would add that, perhaps, the time limit 2010-2024 could be extended, to try to identify more relevant articles, as well as it is worth asking whether to limit the search to WoS and Scopus.
• Finally, I think that an explicit reference to the concept of "sustainability", already in the abstract, is useful to connect the paper to the typical topics covered by the journal.

 

To address these suggestions, the abstract was changed and improve to provide with major clarity in comments, concepts methodology and results, giving space limitations; furthermore, the selected timeframe (2010–2024) was defined to ensure coherence and relevance. It begins shortly before the global adoption of the Sustainable Development Goals in 2015 -allowing us to observe shifts in research and policy linked to SDG 7- and includes recent years marked by rapid changes in PV costs and adoption strategies. Additionally, this window provides a balanced basis for comparing studies conducted in developing countries, offering a consistent frame of reference for identifying theoretical and empirical trends.

We sincerely thank the reviewer for their thoughtful observations, which have helped us improve the manuscript in a more comprehensive and nuanced manner.