Empowering Consumers within Energy Communities to Acquire PV Assets through Self-Consumption
, Stefan P. M. Chantrel 1,†, Manuel Utz 2,†, Robert Kohrs 1 and Jens Strüker 2Round 1
Reviewer 1 Report
I congratulate the authors on taking up a very important and current topic, which is tokenization of Energy. The article is very interesting, coherent and contains interesting simulation results and conclusions.
Editing notes:
Tables 1-7 are unreadable. It is necessary to enlarge the font.
Lines 68-69, 106-107
The authors justify the functioning of the system with the RED II directive and the provision concerning the share limit of 33%. If I understand correctly, the proposed solution will also work for Citizen Energy Communities as defined in IEMD? If this is true, then it is worth emphasizing the universality of the solution also for other communities.
Lines 165-166
Are there any other alternative tokenization and blockchain approaches to asset ownership? What are the main differences from the proposed solution?
Figure 1
In Germany, does such a system require the installation of additional energy meters, or are those installed by prosumers enough? Who is the owner of the meters? If the owner of the energy meters is not the owner of the property, how late is the data provided by the owner of the meters?
Point 5.3 Community Perspective
Have the authors examined the interest among prosumers in such a solution? Please estimate what percentage is interested.
Is it possible to resign from participation in the mechanism? On what terms? Please comment and possibly indicate this in the article
Have the authors analyzed the presence of an energy storage in PAOS in order to increase self-consumption and use it as an element for tokenization? - similar to PV?
Will the presented model work for larger energy communities? For example, for energy cooperatives with dispersed participants? If tokenization could also apply to energy cooperatives on rural areas and accelerate the processes of energy transformation, it is worth signaling it in the second point of the article and pointing to some examples. For example: https://doi.org/10.3390/en14113226; https://doi.org/10.3390/en15030703
Line 338-342
Is a secondary market possible after the purchase of 100% shares in the PV source? It is worth writing about it in the article.
Lines 362-366
At what price the token will return to the general pool when its owner leaves PAOS. It is worth writing about it in the article.
Author Response
Many thanks for your valuable feedback. Please find our responses directly under your remarks.
Reviewer: Tables 1-7 are unreadable. It is necessary to enlarge the font.
Answer: We will do the final formatting at the end of the reviewing process again but already reworked the tables.
Changes done: Table 1-7 are now the same font size as the rest of the paper. Additional formatting was done to make those tables fit into the paper layout. For readability issues we did not mark the change in size of the tables in the paper in a different color, only when we changed the wording.
Reviewer: The authors justify the functioning of the system with the RED II directive and the provision concerning the share limit of 33%. If I understand correctly, the proposed solution will also work for Citizen Energy Communities as defined in IEMD? If this is true, then it is worth emphasizing the universality of the solution also for other communities.
Answer: Indeed, it is also applicable for Citizen Energy Communities, but we focus on the regional aspect for this study. One aim is to enable consumption close to the production and thereby reducing grid stress. By separating production and consumption sites, an EMS could be incentivized for a timewise match but does not always go in line with a spatial match (and may lead to redispatch).
Changes done: We added a section in the introduction after the research question (line 43-48) stating this motivation and another section in the literature part on energy communities (line 84-94).
Reviewer: Are there any other alternative tokenization and blockchain approaches to asset ownership? What are the main differences from the proposed solution?
Answer: Yes, there are indeed other blockchain approaches to asset ownership. One of them being the joint purchase of PV plant share at the initiation stage of an energy community.
Changes done: In chapter 2.2 we added a section elaborating on the difference between such an approach and our PAOS (line 131-135).
Reviewer: (On figure 1) In Germany, does such a system require the installation of additional energy meters, or are those installed by prosumers enough? Who is the owner of the meters? If the owner of the energy meters is not the owner of the property, how late is the data provided by the owner of the meters?
Answer: This is a verry good question. Metering is a major issue that can increase costs a lot. Especially the smart meter gateway infrastructure in GER is a frequently discussed issue, which we could argue about for pages. In a nutshell: we need smart meters that are capable of measuring 15min energy consumption for each consumer and one smart meter for the PV plant. The energy matching is calculated ex-post. The EMS only needs to have the knowledge about the billing/energy distribution mechanism and will use load and production forecasts, so a delay in providing the actual values of the last 15min is no problem for the optimization. However, using the HAN / CLS interface of a SMGW real time data should be available (even though it is not used for the actual billing). In the exemplary building for this study the required infrastructure is in place. With most of the existing infrastructure the imagined system is not possible, the meters would need to be replaced. However, in the future energy system smart meters will be the standard.
Changes done: We did not change anything in the paper, since the whole topic would open a side story which we think would not benefit the overall paper.
Reviewer: (On Section 5.3) Have the authors examined the interest among prosumers in such a solution? Please estimate what percentage is interested.
Answer: Due to the scope of the paper, we were not able to investigate prosumers' interest in POAS. That is because factors such as income, available leisure time and use thereof, sense of community, etc. are important for determining participation rates in addition to living situation, which we were not able to examine within the scope of the paper. However, following Koirala et al. 2018 investigating socio-psychological factors for participation in energy communities, more than 50% of prosumers might have an interest in participating.
Changes done: We added a part in the outlook to mention the need to check the acceptance rate (line 603-607)
Reviewer: Is it possible to resign from participation in the mechanism? On what terms?
Answer: Participation in PAOS is strictly voluntary for prosumers. If a prosumer decides to participate, he or she can terminate his or her participation. The tokens received must be transferred back to the Green Energy Token Contract by the customer as part of the termination. This process step is currently not yet automated.
Changes done: We included a short part in 4.3.2 (line 400-403)
Reviewer: Have the authors analyzed the presence of an energy storage in PAOS in order to increase self-consumption and use it as an element for tokenization?
Answer: We included the presence of battery storage in the form of the storage of battery electric vehicles within different teams (see Section 5.3). The electricity charged by these BEVs is included in the developed token model, as is the electricity consumed by the residential units. However, we did not include any stational battery storage in the usecase scenario, but it is an interesting idea to use the same mechanism to divide available battery storage between the members. A challenge may occur in the control of the battery so the operation goes in line with the individual interests of the members (but in most cases the community benefit should match the individual targets).
Changes done: We added the idea in the outlook (line 597-599)
Reviewer: Will the presented model work for larger energy communities? For example, for energy cooperatives with dispersed participants? If tokenization could also apply to energy cooperatives on rural areas and accelerate the processes of energy transformation, it is worth signaling it in the second point of the article and pointing to some examples.
Answer: Our model is generally also suitable for larger energy communities. If the legislation of the respective country permits so, our model can also be interesting for energy cooperatives in rural areas.
Changes done: A part was added in chapter 2.1 (line 84-94, especially line 91-94)
Reviewer: Is a secondary market possible after the purchase of 100% shares in the PV source? It is worth writing about it in the article.
Answer: We have addressed the issue of the secondary market in chapter 4.5. Once all PV assets are owned by the energy community members, the Green Energy Tokens can be used, for example, to pay for car sharing services. If your question is about a secondary market of the PV assets, i.e., a sale of the PV system itself, then the model we have developed does not allow for this.
Changes done: No changes done
Reviewer: At what price the token will return to the general pool when its owner leaves PAOS. It is worth writing about it in the article.
Answer: If a prosumer decides to participate, he or she can terminate his or her participation. The tokens received must be transferred back to the Green Energy Token Contract by the customer as part of the termination. This process step is currently not yet automated. For governance reasons, we currently do not consider automation to be appropriate here either. This is because the manual transfer of the tokens back to the energy community member means that the energy supplier still has the opportunity to contact the member and ask about the reasons for the termination. Return tokens will not be compensated by the utility, when a member leaves all values stay within the system without any remuneration for the leaving member.
Changes done: We added a part in chapter 4.3.2 (line 400-403).
Reviewer 2 Report
The manuscript “Empowering Consumers within Energy Communities to
acquire PV Assets through Self-Consumption” presents a token-based system of gradual transfer of Solar Photovoltaic ownership rights for residential and small-scale commercial consumers. A case study is simulated for a German Energy Community
This is a very interesting and ongoing topic.
However, some specifications have to be provided for improving the understandability of this study.
Abstract
Some results of this study should be addedLiterature review
Pag. 3
There are many square brackets empty. Please check
Please, mention the possibility to determine the solar radiation on building surface by GIS application (e.g.
Photovoltaic Generation Integration with Radial Feeders Using GA and GIS https://doi.org/10.1155/2020/8854711
GIS-based decision support for solar photovoltaic planning in urban environment
Sustainability in Energy and Buildings, 865-874 )
- Material and methods
It is useful to present the climatic data ( i.e. monthly solar radiation) for Kaiserslautern.
Table 2 –Simulation setup
the characteristics of the 7 PV plants have to be provided ( i.e. azimuth, tilt, square meter of PV plants, kind of PV module, efficiency of PV module ).
Please, highlight the ratio between the overall annual consumptions ( 113531 kWh) and the Annual PV production (46112* kWh), which is 40,6%.
The authors have to comment on how this ratio affect the results presented in this study.
Moreover, it could be also useful to report the ratio between the Annual PV production and PV plant nominal power (40 kW), which is about 1150 kWh/kW.
- Prosumer Asset Ownership System (PAOS)
Please define each number and symbol in Figures 1 and 2
Figure 3 – the words are unreadable – Take care to define each number and symbol used within such figure
- Results and Discussion
Table 6. Key performance indicators of the simulation results
Please specify what do mean
com. PV share of
Agg. ind. Shares
Figure 4.
Define Residual and utility grid
Figure 6. Self-consumption share and self-sufficiency share
These results have to be further commented. What do represent the green and orange areas?
What about self-sufficiency?
Author Response
Many thanks for your valuable feedback. Please find our responses directly under your remarks.
Reviewer: Abstract: Some results of this study should be added
Answer: We added the three major KPIs in the Abstract. Payback time, Time to distribute \50% of the shares and self-consumption share.
Changes done: line 10-11
Reviewer: Literature review: Pag. 3: There are many square brackets empty. Please check.
Answer: Concerning the empty square brackets, this is a misunderstanding. The brackets are used in the quote to signal we left out part of it.
Changes done: We replaced the square brackets by round brackets. (line 127-128, 139)
Reviewer: Please, mention the possibility to determine the solar radiation on building surface by GIS application (e.g. Photovoltaic Generation Integration with Radial Feeders Using GA and GIS https://doi.org/10.1155/2020/8854711; GIS-based decision support for solar photovoltaic planning in urban environment Sustainability in Energy and Buildings, 865-874)
Answer: We do not see the advantages of including papers on GIS based determination of solar radiation. It is a good think to use when estimating the PV potential for energy community buildings, however, within our study it is of secondary importance how the solar radiation was determined. The important take away message in the planning of PV systems is, that our system creates benefits to install PV systems for various stakeholders.
Changes done: None (but a section on the whole PV data generation was added, see next comment)
Reviewer: Material and methods:
It is useful to present the climatic data ( i.e. monthly solar radiation) for Kaiserslautern.
Table 2 –Simulation setup the characteristics of the 7 PV plants have to be provided ( i.e. azimuth, tilt, square meter of PV plants, kind of PV module, efficiency of PV module ).
Material and methods: Please, highlight the ratio between the overall annual consumptions ( 113531 kWh) and the Annual PV production (46112* kWh), which is 40,6%. The authors have to comment on how this ratio affect the results presented in this study. Moreover, it could be also useful to report the ratio between the Annual PV production and PV plant nominal power (40 kW), which is about 1150 kWh/kW.
Answer: Indeed, the mentioned points provide valuable information to point out that the PV plant is in a favorable position. We decided that for the main story line it is sufficient to provide the PV consumption and PV peak values. However, we attached a lot of supplementary information on the whole sizing procedure, with a major part on the PV system in the appendix and reference it in Section 3.2. Additionally, we added a sentence on the mentioned PV/consumption ratio, together with the EV/consumption ratio defining the flexibility boundaries. We also added two sentences in the conclusion chapter on this topic.
Changes done: Section 3.2: line 230-232 now points to the appendix which addresses the PV sizing in detail in line 644-656. Figures A1, A2 and A3 were added, together with tables A1 and A2. The mentioned ratios are expressed in line 238-241 and discussed in the conclusion (lines 581-585 and 586-587).
Reviewer: Prosumer Asset Ownership System (PAOS): Please define each number and symbol in Figures 1 and 2 Figure 3 – the words are unreadable – Take care to define each number and symbol used within such figure
Answer: We reworked the captions of figure 1 and 2 to include all abbreviations, numbers, and relevant color meanings in it. In addition, the sections dealing with those figures were modified. For figure 3 we added the zoomed in figures in the appendix and refer to this in the main paper body. Since the interface is in German, also a small description of the UI is provided in the appendix.
Changes done: Captions Figure 1 and 2. Appendix B line 664-684 + Figure A4. Link to the appendix in line 416.
Reviewer: Results and Discussion
Table 6. Key performance indicators of the simulation results: Please specify what do mean com. PV share of Agg. ind. Shares
Figure 4. Define Residual and utility grid
Figure 6. Self-consumption share and self-sufficiency share: These results have to be further commented. What do represent the green and orange areas? What about self-sufficiency?
Answer: Table 6: We renamed the headers. „Agg. Ind. Shares“ is now „$\sum$ individual shares“ and „com.“ was replaced with „community“. We hope this is clearer now. The difference between building and aggregated individual shares is also mentioned in section 3.3 on KPIs. Figure 4: We provided an explanation of „Residual“ and „...utility grid“ in the caption. Figure 6: The green and orange areas represent the quantiles around the mean value. We rephrased the caption to clarify. Otherwise, we did not extend the section on those three subfigures. The major takeaways should be that the PV plant could be extended, and the number of flexibilities could be increased (which we state in the text). Both would benefit all stakeholders. These findings also close the link to the numbers you pointed out in the previous comments (PV/consumption and Flexibility/consumption). Side note: From an economic perspective for the utility the self-consumption is more important than the self-sufficiency. Therefore, this factor is mentioned more often.
Changes done: Headers in Table 6 and Caption on Figure 4 were modified.
Reviewer 3 Report
Interesting paper; it is, however, more of an "application" paper with a minor scientific contribution. Some specific comments are the following:
1) In line 43, the expression "an electric model" is incorrect.
2) In lines 76-78 and other parts of the paper, the authors claim that a shared PV system co-ownership model within an energy community is missing. That is not true as there are examples of such models in practical operation (see [1]). This doesn't reduce the value of the paper, i.e., to design an ICT platform for governing and securing the operation of such a model. I suggest, however, to the authors to delineate the economic/business model (that already exists in several countries in the form of energy collectives/cooperatives) from the technical aspect.
[1] Chronis, A. G., Palaiogiannis, F., Kouveliotis-Lysikatos, I., Kotsampopoulos, P., & Hatziargyriou, N. (2021). Photovoltaics Enabling Sustainable Energy Communities: Technological Drivers and Emerging Markets. Energies, 14(7), 1862.
3) In section 3.2, please give details about the case study. Which are precisely the controllable units (and how many), what are their capacities? Technical limits?
4) Also, I suggest improving the section presenting the blockchain application (Section 4.3), which is crucial for answering the research questions. Please provide more details about the smart contract, the designed protocol, some typical use cases, etc. By the way, why is it placed after the case study section? That is a bit uncommon.
5) Please explain a bit better the definitions of the key performance indicators. I also suggest avoiding the use of all those initials in the text, they are difficult to follow.
Author Response
Many thanks for your valuable feedback. Please find our responses directly under your remarks.
Reviewer: Interesting paper; it is, however, more of an "application" paper with a minor scientific contribution.
Answer: Thanks for your comment. You are right: our paper has a high application relevance. Nevertheless, we see a scientific added value in the fact that the developed PAOS can in principle be transferred to other RES and that the economic viability of gradual ownership transfer on blockchain basis could be shown.
Changes done: None
Reviewer: In line 43, the expression "an electric model" is incorrect.
Answer: You are right, this is the wrong expression. We changed the whole sentence to describe in more detail what exactly is presented in the mentioned section.
Changes done: Rephrased line 51-54
Reviewer: In lines 76-78 and other parts of the paper, the authors claim that a shared PV system co-ownership model within an energy community is missing. That is not true as there are examples of such models in practical operation (see [1]). This doesn't reduce the value of the paper, i.e., to design an ICT platform for governing and securing the operation of such a model. I suggest, however, to the authors to delineate the economic/business model (that already exists in several countries in the form of energy collectives/cooperatives) from the technical aspect. [1] Chronis, A. G., Palaiogiannis, F., Kouveliotis-Lysikatos, I., Kotsampopoulos, P., & Hatziargyriou, N. (2021). Photovoltaics Enabling Sustainable Energy Communities: Technological Drivers and Emerging Markets. Energies, 14(7), 1862.
Answer: Thank you very much for your comment. You are right that PV co-ownership models within energy communities are rare but do exist. However, a prosumer asset ownership system like the one we have developed does not exist yet. The main difference between the PAOS we developed, and the approach described by Chronis et al. 2021 is the way ownership of PV assets is transferred to the energy community members. Whereas in Chronis et al. 2021, members join at the initiation of an energy community and its members collectively invest in PV systems to meet " a large part (around 80%) of their annual electricity needs," in our PAOS the focus is on the tokenized transfer of ownership of PV systems through electricity consumption itself. Thus, instead of the organizational alliance of energy community members, there is a small-scale and gradual transfer of ownership based on blockchain. This mechanism also significantly lowers the threshold for customers to become prosumers.
Changes done: We added lines 131-135 in 2.2 mentioning the source above. Additionally, we inserted “easily accessible way” in line 97 to soften the missing research statement.
Reviewer: In section 3.2, please give details about the case study. Which are precisely the controllable units (and how many), what are their capacities? Technical limits?
Answer: Indeed, the section on the EMS is missing the information about the controllable devices, which are the electric vehicles. Thank you for pointing this out. We added the missing information in the text. Additionally, in alignment with the remarks of another reviewer, who wanted to have additional information about the PV timeseries creation, we decided to put the specific details about the controllable BEVs in the Appendix.
Changes done: The appendix was added. In line 258 we added the controlled charging of the BEVs to the former statement about the EMS.
Reviewer: Also, I suggest improving the section presenting the blockchain application (Section 4.3), which is crucial for answering the research questions. Please provide more details about the smart contract, the designed protocol, some typical use cases, etc. By the way, why is it placed after the case study section? That is a bit uncommon.
Answer: Thank you for your comment. We cannot disclose the source codes of the three smart contracts described (Billing Contract, Green Energy Token Contract and Marketplace Contract) for project-related reasons. However, to provide more clarity regarding the smart contracts, we have added the following section in 4.3.2: All three developed smart contracts are written in Soliditity and can be deployed on the Ethereum Virtual Machine and related software platforms. We have deliberately placed the structure and function of the PAOS after the description of the case study, as without the description of the framework parameters (number of housing units, underlying economic assumptions, etc.), an understanding of the interdependent elements described in the PAOS may not be achieved.
Changes done: Added lines 349 - 350
Reviewer: Please explain a bit better the definitions of the key performance indicators. I also suggest avoiding the use of all those initials in the text, they are difficult to follow.
Answer: We refactored the equations and the text describing those. Additionally, we added two sentences explaining the costs savings when maximizing self-consumption and self-sufficiency. Concerning the initials, we stick with SCS and SSS and would argue that those two abbreviations can still be handled. Whenever they occur in the text, we also reference to section 3.3 where they are defined.
Changes done: Section 3.3 was completely reworked.
Reviewer 4 Report
It’s a well written paper
Introduction section provides a rationale for the study
Literature review is relevant and up to date
Lines 104-105: some references are not provided in brackets!
Research approach is sound and results are well presented.
Author Response
Many thanks for your overall approvement of out paper.
Concerning your remark on the empty brackets. We replaced the square brackets by round brackets. There are no missing sources, but the brackets are part of the direct quote where we left out parts. This also caused some confusion with other reviewers but should be clear now.
Reviewer 5 Report
Excellent paper and well-presented concepts.
Should run grammar check (Grammarly etc.) for small errors.
I would like to see more clarity on Fig. 2 with specific reference to the values in the figure. The paragraph below Fig. 2 could be reworked as I struggled to follow the logic.
Author Response
Many thanks for your overall approvement of out paper. Please find your two remarks answered below:
Reviewer: Should run grammar check (Grammarly etc.) for small errors.
Answer: We went through the paper again and corrected some typos and grammar issues. Main issue was that we jumped between British and American English spelling sometimes, this is now corrected to all American style. A final language editing will be done by the journal as stated in the MDPI Electricity Instructions for Authors section.
Changes done: Many small adaptations which are marked in the pdf but to numerous to list here.
Reviewer: I would like to see more clarity on Fig. 2 with specific reference to the values in the figure. The paragraph below Fig. 2 could be reworked as I struggled to follow the logic.
Answer: We reworked the section and included examples directly referring to the values used in the figure. We also numbered the different steps and linked those to the text. Additionally, the caption of the figure was extended so the figure becomes more self-explaining, without going through the corresponding section.
Changes done: Reworked caption in Fig. 2. Added examples directly linking to the figure in line 360-361, 364-365 and 377-370
Round 2
Reviewer 3 Report
My comments are addressed
