Energy Valorization Strategies in Rural Renewable Energy Communities: A Path to Social Revitalization and Sustainable Development

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

An interesting paper that brings together valorisation strategies based on technical scenarios with the social benefits of the valorisation.

Three general remarks:

The EC is based on a supra-structure model with many villages. There is little information on the EC itself. What does, for instance, decision-making mean, one member, one vote, and what are the consequences for the individual villages? Democracy takes place on the regional level. But might decisions disfavour certain villages, and how? What about member percentages in all villages, now set at generally 14%? P18 What do regional priorities mean?

The relation between surplus energy that leads to valorisation and money and local development, particularly operationalised as local jobs, is a black box. How would this work in terms of local economic investments?

Does the quality of the regional and local grid play a role? Does grid flexibility already have a financial value in Spain? What is the role of the DSO (energy project connections)?

Some specific questions and remarks:

• In the technical scenario, it looks far fetched to expect to sell either EV charging electricity or hydrogen to passing customers (high traffic assumption). Instead, one would expect a relation between EV charging. Hydrogen use and the local transport economy. This is also an important sustainability component as it will avoid fossil fuel use.
• P 2: The discussion on retailing. Are cooperative members not the first customers for self-consumption of the Aggregated PV project?
• P3 For the discussion later in the article, adjust the discussion on battery prices (as this si the chosen storage option)
• Section 1.2 Quality of life attracts people who can, for instance, work remotely. So, money can be invested in quality of life, village marketing, and internet infrastructure to attract people. Direct quality would be schools and social life. Attracting people is not only based on locally created jobs. This is underexpressed in the paper.
• Section 2 Materials(???) and methods?
• P 6 Benefits are analysed in terms of equivalent person years. Here, the causal chain reasoning between economic value and financial benefits in jobs is missing.
• 1 Case study. Does it have only volunteers or professional staff in the EC, or only volunteers? How likely is the dominance of the larger communities in regional democratic decision-making? P17 administrative capacity?
• P 7 There is data on electricity contracts but not on the number of contracts of EV members or membership data per village?
• P8 What does selling to other consumers mean, selling to non-EC members?
• P8 Are the PV project mounted PV or also rooftop solar? What does self-consumer (used throughout the article) mean? Prosumers with a rooftop PV installation?
• P 11: Participants' gains are gains for the EC Members? What is needed to become an EC Member (investment) and profit from the distribution of benefits?
• What role does EC Membership play in the energy project finance/P19? What does realistic finance mean in this perspective? What can members bring together?

Author Response

Dear Reviewer,

Thank you very much for your valuable comments and suggestions to improve our paper. Below, we provide detailed responses to each of your points, which we hope address your concerns appropriately. Several of your suggestions have been directly incorporated into the manuscript. Others are addressed here, considering that we have requested the editor to make both the reviewers’ reports and our responses publicly available, ensuring they remain accessible to any interested reader. This approach allows us to elaborate further on your recommendations.

Moreover, given the reviewer's expertise in energy communities and his/her interest in the technical and operational aspects of CERCA’s specific model—beyond the social framework we present, which is applicable to other energy community models—we would like to kindly invite him/her to visit the JALON project website, where he/she can find technical documents that may be of interest: https://jalon-ce.eu

Best regards,

 

The EC is based on a supra-structure model with many villages. There is little information on the EC itself. What does, for instance, decision-making mean, one member, one vote, and what are the consequences for the individual villages? Democracy takes place on the regional level. But might decisions disfavour certain villages, and how? What about member percentages in all villages, now set at generally 14%? P18 What do regional priorities mean?

In response to the reviewer's question, we consider that CERCA’s detailed governance structure is not directly relevant to the objectives of this paper and thus does not belong in the methodology section. However, in line with our Open Peer Review policy, we provide the following clarification given CERCA’s unique characteristics.

CERCA is not a federation of smaller energy communities, but a single rural energy community comprising 67 villages. It offers six participation models to accommodate diverse community involvement. Individuals may consume energy from CERCA facilities regardless of cooperative membership.

Members pay a one-time fee of €100 and cover 60% of their desired power share; the remaining 40% is financed through investors, grants, or subsidies. Non-members contract energy services with CERCA, which, as an energy retailer, manages both its own surpluses and those from neighbors with private installations who wish CERCA to valorize them. CERCA can also trade surpluses on the market or purchase energy when needed, enabling scenarios like 1C or 2C.

Cooperative members are grouped by installation, each limited to 100 kWp to comply with Spanish regulations, which also restrict collective self-consumption to a 2 km radius. Users outside this range, or non-members, consume surplus energy and pay for it as standard consumers.

For this study, we simplified the system design by modeling installations of 3 and 60 kWp. In practice, as today, CERCA operates 18 installations across 15 villages, ranging from 3 to 100 kWp. Guided by the Diffusion of Innovations theory, we assumed that 14% of the population—representing early adopters—would define the initial energy demand, uniformly distributed among users. This assumption, while useful for early-stage design, does not reflect the current reality.

Although such simplifications aid conceptual modeling, they neglect real-world variables such as panel efficiency, system losses, and individual demand profiles. In practice, accurate system design will require actual consumption data to estimate surpluses and guide optimization between Scenarios 1A, 1B, or 1C in early stages, and between Scenarios 2 or 3 as the community evolves. The method remains robust, with figures and configurations expected to adapt over time. Continued engagement with local stakeholders is key to aligning energy demand aggregation with the most appropriate scenario.

Regarding the regional cooperative structure, its main purpose is to optimize administrative and operational resources, enabling smaller villages—who otherwise might not establish energy communities independently, to participate without losing control over their local energy management.

Concerning the question of whether larger villages might exert more influence over the community’s decisions than smaller ones, the cooperative is not designed to allocate power proportionally to installed capacity. The decision is made one member- one vote. Logically, more members come from Catalayud, the largest town in the region with around 20,000 inhabitants, while other villages have fewer than 1,000 residents, and the remaining 63 villages total about 10,000 people.

In practice, most of the 128 cooperative members currently come from small villages rather than larger ones. Moreover, surplus management is conducted at the level of each installation, which reduces the risk of any locality being disadvantaged. While the paper might appear to suggest a uniform approach to surplus management across all villages and facilities, this is not the case. Different models can be applied in different villages and tailored to each installation, depending on the actual surplus generated—both in quantity and in hourly distribution—once such data becomes available.

In a second phase, we explored a supra-local model in which surpluses are managed collectively rather than at the level of individual villages, which is the reality now. In Scenario 1C, individual management increases the population served by 15%, whereas collective management raises this figure to 26%. In this context, the reviewer’s question becomes particularly relevant, as it raises a key issue: how should the benefits of the additional 11% be distributed? As the reviewer noted, there is a risk that voting dynamics could lead to a concentration of investment in certain villages at the expense of others. Thus, one of the fairest approaches could be to base the distribution on regional priorities identified by the regional government. For example, investments could be directed toward areas that have suffered natural disasters or are at higher depopulation risk, helping to prevent depopulation and promote economic revitalization. This strategy would consider the specific needs of different areas and ensure that resources are allocated in a way that supports overall regional resilience and equitable development.

The relation between surplus energy that leads to valorisation and money and local development, particularly operationalised as local jobs, is a black box. How would this work in terms of local economic investments?

Yes, we agree that the link between surplus energy valorisation, monetary income, and local development—particularly through local job creation—remains largely a "black box" at this stage. As we note in lines 444–449, many strategies could be pursued, but it would be inappropriate to define specific actions without a deep understanding of the demographic, economic, and social conditions of each village.

Nonetheless, we can anticipate some potential pathways. For instance, in many small villages, social life disappears during the winter months because local bars and cafes close due to insufficient turnover. One possible action could be for the EC to partially subsidize the salaries of bar or shop owners during these low-activity periods, ensuring these businesses remain open and preserving the remaining social cohesion while a job is maintained.

Similarly, other interventions could include supporting the maintenance of essential services (such as small grocery stores, pharmacies, or maintenance services), providing seed funding for new rural businesses, promoting local tourism initiatives linked to energy sustainability, or even co-financing part-time employment positions linked to the EC’s management and maintenance activities.

The critical point is that valorised income from energy surplus would act as a flexible tool for locally prioritized investments. Each village through democratic decision-making processes, would identify its most urgent needs and decide how to allocate the funds coming from the valorization—thus aligning the technical management of surplus energy with tangible social and economic development goals.

Theoretical exercises like the one proposed in this paper must ultimately be validated in practice—and this is precisely CERCA’s objective. We aim to share the lessons learned and evaluate the outcomes of surplus valorization management over the medium to long term. Social impacts, such as reversing depopulation trends, cannot be meaningfully assessed in the short term.

Does the quality of the regional and local grid play a role? Does grid flexibility already have a financial value in Spain? What is the role of the DSO (energy project connections)?

Yes, the quality of the regional and local grid plays a critical role. In rural areas, grid infrastructure is often older and less robust, which can limit the technical potential for new energy projects, especially when it comes to integrating distributed renewable energy sources. Weak grids can lead to curtailment of surplus energy production or require additional investments in grid reinforcement, impacting project feasibility. Furthermore, the Distribution System Operator (DSO) typically does not proactively invest in reinforcing the grid for community energy projects; instead, reinforcement costs often fall on the project developers themselves, increasing financial challenges for smaller initiatives. The prices per kWp considered in the paper reflect this reality.

Currently, in Spain, grid flexibility itself does not yet have a significant, explicit financial value for small-scale producers or energy communities. Although regulation is evolving, mechanisms such as flexibility markets, ancillary services, dynamic tariffs, or local flexibility services are still in pilot phases or have limited implementation. As a result, communities cannot directly monetize flexibility services at this time.

CERCA is working on a Virtual Power Plant , a management software platform that operates both locally and interfaces with the grid, proactively addressing the upcoming regulation of ancillary services, which has not yet been approved in Spain. Like the social management model presented in the article, we are also anticipating the regulation of energy communities, which has not yet been transposed, demonstrating which technical models can truly facilitate social impact.

The Distribution System Operator (DSO) plays a crucial role in connecting new projects. They evaluate connection requests, assess grid capacity, and authorize connections. They are also responsible for reading the meters of collective self-consumption systems and communicating the energy distribution to each consumer. In practice, obtaining grid connection permits can be a bottleneck, especially in rural areas with limited hosting capacity.

Some specific questions and remarks:

• In the technical scenario, it looks far fetched to expect to sell either EV charging electricity or hydrogen to passing customers (high traffic assumption). Instead, one would expect a relation between EV charging. Hydrogen use and the local transport economy. This is also an important sustainability component as it will avoid fossil fuel use.

We agree that expecting significant revenue from EV charging or hydrogen sales to transient customers may be overly optimistic, particularly in rural contexts. However, as noted in the paper, we have only applied this scenario to villages located near one of Spain’s six main roads—specifically, the corridor connecting Madrid and Barcelona. The selected area, around Calatayud, is strategically situated midway between both cities, about 2,5 hours to each.

Our intention was not to assume high external demand, but rather to explore the technical feasibility and potential of integrating such infrastructure into the local transport economy. Indeed, as the reviewer rightly points out, the sustainability value lies in supporting local mobility and reducing dependence on fossil fuels. If the energy community decides to pursue this model, a dedicated study will be carried out to assess its viability, considering also internal demand. This could make this scenario for some villages that we have already discarded because of their location far from the railway.

We have included this clarification, lines 394/397 of the manuscript, to ensure future readers take this into account.

 

• P 2: The discussion on retailing. Are cooperative members not the first customers for self-consumption of the Aggregated PV project?

As previously mentioned, CERCA offers six participation models, with cooperative members naturally being the primary beneficiaries of self-consumption. However, the possibility of selling surpluses to other villagers only becomes viable when CERCA operates as an energy retailer. This allows, for example, residents living beyond the 2 km legal radius from an installation to also participate in the energy community.

This approach arises from the lack of specific support measures for energy communities. Once CERCA assumed the role of energy retailer, it also identified the opportunity to manage surpluses from privately owned facilities within the community—installations that are not part of the cooperative itself. Additionally, CERCA can purchase green electricity from the market to ensure a stable supply for those villagers who choose CERCA as their energy provider.

For those who are not the primary self-consumers and therefore do not contribute to financing the facilities, CERCA applies a cost-based electricity price when selling them electricity.

 

• P3 For the discussion later in the article, adjust the discussion on battery prices (as this si the chosen storage option)

Page 3 is just a description of the state-of-the-art.  The type of battery and price considered in the article are described in section 2.3.2.

 

• Section 1.2 Quality of life attracts people who can, for instance, work remotely. So, money can be invested in quality of life, village marketing, and internet infrastructure to attract people. Direct quality would be schools and social life. Attracting people is not only based on locally created jobs. This is underexpressed in the paper.

 

You're right, and we conducted an extensive review to identify the potential social impacts that an energy community can generate, as summarized in Table 1. However, evaluating the actual impact in practice is extremely challenging. Our work aims to quantify the value of surplus energy in terms of potential job equivalents under each scenario. This does not imply that these jobs will be created directly or automatically.

As you correctly pointed out about the "black box" of local impact, there are indeed several actions that may not result in immediate job creation but rather help create the economic conditions necessary for future employment. These may include investments in promoting the village, subsidizing part of the salary for seasonally affected jobs, supporting the rehabilitation of housing or public buildings, and similar initiatives.

However, one thing is clear: the greater the value generated from surplus energy valorization, the more opportunities there will be for social reinvestment. In our view, it is essential to go beyond merely setting up an energy community to implement valorization mechanisms that—when limited to individual benefit, as illustrated in Table 2—tend to remain more personal than truly social.

 

• Section 2 Materials(???) and methods?

 

Changed: Methodology.

 

• P 6 Benefits are analysed in terms of equivalent person years. Here, the causal chain reasoning between economic value and financial benefits in jobs is missing.

We appreciate this observation. As clarified in the revised text (see Section 6), our analysis does not intend to suggest a direct causal relationship between economic value and immediate job creation. The person-year equivalents are used as a proxy to quantify the social value of surplus energy valorization in comparable terms. However, we acknowledge that the causal chain—from financial benefits to actual employment—is complex and context-dependent. It involves indirect mechanisms that require complementary local strategies, and reinvestment plans to foster the social and economic conditions necessary for job creation. We have now made this clearer in the manuscript to avoid any misinterpretation. Lines 484-489.

 

•  Case study. Does it have only volunteers or professional staff in the EC, or only volunteers? How likely is the dominance of the larger communities in regional democratic decision-making? P17 administrative capacity?

CERCA currently employs two full-time staff members, thanks to funding from the JALON Project, which also supports this study. Once this initial phase of external support concludes, the structure must be sustained through the energy community’s own revenue generation. As stated in our analysis, the benefits from energy surplus valorization should, at a minimum, cover the cooperative’s operating costs, including staff salaries. This point has been clarified in line 447 of the manuscript.

• P 7 There is data on electricity contracts but not on the number of contracts of EC members or membership data per village?

We reiterate that this is a theoretical study conducted during the design phase of the energy community. As previously mentioned, CERCA is currently working to integrate more participants and develop the necessary infrastructure to achieve a total installed capacity of 4 MWp by mid-2026.

Once this minimum structure is in place, the social and surplus valorization plan—key to generating medium- and long-term value—will need to be re-evaluated, taking into account the installations that have been successfully launched, the active villages, and the number of participants (currently 128 and not all in the selected villages of the study presented).

This evaluation will allow the activation of one or more valorization scenarios, either at the individual installation level or by leveraging CERCA’s shared resources as the managing entity.

• P8 What does selling to other consumers mean, selling to non-EC members?

Yes, as explained above. For us, participating in the energy community does not necessarily mean being a cooperative member. As a villager, you can support and engage with the energy community and its principles in various ways: by being an external consumer, allowing CERCA to manage the surpluses from your private installation, investing in the cooperative, etc.

 

• P8 Are the PV project mounted PV or also rooftop solar? What does self-consumer (used throughout the article) mean? Prosumers with a rooftop PV installation?

Among the real 18 facilities set up by the cooperative, some of them are rooftop solar and some of them mounted PV. CERCA Self-consumers are those who are members of the cooperative, finance the shared facility and have access to the energy generated through such facility.

 

• P 11: Participants' gains are gains for the EC Members? What is needed to become an EC Member (investment) and profit from the distribution of benefits?

Yes, we have considered participants' gains as the benefits accruing to energy community members. So far, no gains have been distributed, as the first facilities were installed and connected less than a year ago. To become a member, individuals pay a €100 membership fee and contribute to the investment in their facility—approximately 60% of the power capacity they request, while the remaining 40% comes from grants and external investors.

 

• What role does EC Membership play in the energy project finance/P19? What does realistic finance mean in this perspective? What can members bring together?

 

Currently, each member of the cooperative finances 60% of the power they request in the installation, which is located within a 2 km radius of their consumption point.

 

If scenarios involving the use of batteries or any of those included in Category 3 are chosen, new investments in equipment will be required, which must be financed by the cooperative. As of today, CERCA has not yet made a definitive decision on who will assume the cost of these investments.

 

In fact, as stated in this work, this is a preliminary design intended to guide the founding members on the potential of a Renewable Energy Community (REC) to address challenges associated with depopulation. Naturally, the final model to be implemented will need to be reassessed once actual operating conditions are known—something that could be evaluated after two and a half years of activity in the region, aimed at achieving the target of 4 MWp in installed capacity.

 

However, one point is clear: if the cooperative's own members are unable to finance the additional infrastructure needed to implement such value-added scenarios—such as those involving batteries or hydrogen—and if the required investment exceeds a reasonable average threshold, then, considering that the cooperative already has 128 members, 18 installations, and 830 kWp in operation, obtaining external financing from investors or banks would represent a lower-risk and more viable project than attempting to secure such funding at the initial stage of the REC.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have investigated the topic “Energy Valorisation Strategies in Rural Renewable Energy Communities”. Though the subject has gained increasing relevance in light of global sustainability objectives and the transition to decentralized energy systems, this paper represents a noteworthy effort to develop innovative frameworks and actionable strategies for facilitating energy transition in rural contexts. However, I have few comments that can improve the manuscript.

1. Abbreviation should not be used in the abstract.
2. In the abstract, the authors mentioned eight sub-scenarios that were not listed in the abstract.
3. In the introduction, the last paragraph should be re-written showcasing the needs and novelty of the study.
4. Pronouns should not be used in the manuscript such as page 2 line 56. Pages 6line 232 etc.
5. A clear explanation of the Economic profitability shown in Table 3 needs to be explained and related to existing literature
6. Return on investment shown in Table 4 indicates blank in 1B, 2C, and 3A.
7. The conclusion should be summarized incorporating major findings

Author Response

 

Dear Reviewer,

Thank you very much for your valuable comments and suggestions to improve our paper. Below, we provide detailed responses to each of your points, and we hope that our revisions appropriately address your concerns. All of your suggestions have been incorporated into the manuscript.

Bet regards,

Abbreviation should not be used in the abstract.

Changes in lines 8, 18 and 25: energy communities instead ECs.

In the abstract, the authors mentioned eight sub-scenarios that were not listed in the abstract.

Changes to explain sub-scenarios: lines 13-16

In the introduction, the last paragraph should be re-written showcasing the needs and novelty of the study.

The last paragraph has been modified by adding lines 224-226, 228 and 231-232 with information about the need for this work and reformulating the innovative scope of our work.

Pronouns should not be used in the manuscript such as page 2 line 56. Pages 6line 232 etc.

Changes to substitute pronouns in the manuscript: lines 56, 104, 180, 247, 262, 286, 341, 472, 521, 675,842.

A clear explanation of the Economic profitability shown in Table 3 needs to be explained and related to existing literature

An explanation of the economic profitability is added to the text (lines 506-512) with references.

Return on investment shown in Table 4 indicates blank in 1B, 2C, and 3A.

Blanck space was substituted with “–“ (in table 4 and in table 3)

The conclusion should be summarized incorporating major findings

A summary of the conclusion with major findings is added: lines 806-818

Other changes:

Some references where missing: line 336

One reference was mistaken: line 344

Modification of the profitability index since it needs to be expressed as the ratio between the NPV and the investment. In the manuscript it was calculated the same but expressed as a percentage (changes in last column of table 3)

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The article is well presented and structured, but considering that it discusses photovoltaic systems installed in the 6 analyzed areas, there are a few aspects that need to be clarified:

- how was the solar potential evaluated?

- the type of photovoltaic system is not specified (are the panels located on each building - on the roof or is it considered a photovoltaic power station type system that covers the entire consumption of a locality (consumptions presented in Table 2)?

- It only discusses quantitatively the photovoltaic systems installed, but what are their performances?

Author Response

Dear Reviewer,

Thank you very much for your valuable comments and suggestions to improve our paper. Below, we provide detailed responses to each of your points, and we hope that our revisions appropriately address your concerns.

Best regards,

The article is well presented and structured, but considering that it discusses photovoltaic systems installed in the 6 analyzed areas, there are a few aspects that need to be clarified:

- how was the solar potential evaluated?

- the type of photovoltaic system is not specified (are the panels located on each building - on the roof or is it considered a photovoltaic power station type system that covers the entire consumption of a locality (consumptions presented in Table 2)?

- It only discusses quantitatively the photovoltaic systems installed, but what are their performances?

Response:

We understand the reviewer’s concerns, but we would like to clarify that the work proposes a methodology for analyzing the potential social impact of an energy community, based on fully simulated data. The aim is to provide a tool that helps the founding members anticipate whether this solution could address their primary concern: rural depopulation.

Currently, the project is in a 2.5-year technical phase, during which infrastructure is being installed and citizens are being recruited to join the new cooperative. This implementation is not limited to the initially selected municipalities; some will have more installations, others fewer, and new locations are also being included. The goal is to reach a total of 4 MWp installed.

The simulation considers only a ground-mounted installation, evaluated with the solar potential estimated by the PVGIS tool. However, the reality of the project is more diverse: installations are both rooftop and ground-mounted, with capacities ranging from 3 kWp to 100 kWp.

We value the reviewer’s observation, which we consider pertinent. But we chose not to include specific implementation details, as they do not add value to the methodological goals of the study. Even the simulated demand—based on 14% of the population with homogeneous consumption—differs from reality, where installations are tailored to the actual consumption profiles of the participating neighbors.

The next phase of the CERCA project will involve analyzing and projecting the energy surpluses once the 4 MWp are completed, in order to develop a valuation model that reflects the real social impact. This model may be adjusted in the future if additional installations are added.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have addressed my comments successfully and the paper can be accepted.