In recent years, the European Union has promoted the concept of collective self-consumption and the so-called energy communities, with the aim of involving citizens in energy management and offering measures to improve energy efficiency. Spain, following the EU directives, promotes a shared use of energy, especially in urban environments. Therefore, and in accordance with this objective, this work presents the case study of incorporating energy communities including public residential buildings in Vitoria-Gasteiz (north of Spain) belonging to the public institution of the Basque Government. The aim of the study is to identify the possibilities of creating energy communities based on PV energy systems, and to analyze their feasibility considering the self-production and consumption. In addition, the possibility of including a private building rooftop of the Mercedes-Benz factory is also studied in order to produce a greater amount of energy and to be able to supply the completely electric demand of the public residential buildings. In the latter case, an economic analysis is carried out, considering the initial investment of a nearly 5 MWp photovoltaic installation, with a 2 years payback, and an environmental analysis, which shows that this photovoltaic installation would mean a saving of almost 1,600 tons of CO2 per year.
Research Article
Review and proposition of energy communities: The case study of Vitoria-Gasteiz
https://doi.org/10.21203/rs.3.rs-3004442/v1
This work is licensed under a CC BY 4.0 License
Version 1
posted
You are reading this latest preprint version
Energy Community
Photovoltaic potential
Optimal surface of rooftops
The progressive depletion of reserves, combined with the greater difficulties surrounding exploration and extraction activities, highlight the need in advanced economies to move towards the replacement of these energies with others of renewable origin and to reduce energy intensity through savings and efficiency. However, today and on a global scale, the main sources of energy are fossil fuels such as coal, oil and natural gases. Even so, it is becoming increasingly necessary to use naturally available renewable energies, particularly solar energy. For this reason, both in developed and developing countries, techniques for exploiting solar energy through various processes, such as thermal or photovoltaic (PV), are being promoted.
Given the significant number of sun-hours that Spain experiences due to its climate and geographical location, this country has the potential to exploit clean and sun energy to meet its energy needs. However, since a large part of the world's population is concentrated in cities, it is essential to establish sustainable urban plans that utilize available resources and technology. Likewise, in the buildings sector, long-term structural changes are needed, with particular emphasis on the continuous improvement of equipment, on users' consumption habits and on the integration of renewables from the local and community points of view. Several studies have identified urban centers, such as the city of Geneva (Switzerland) (Gassar and Cha 2021), or Miraflores de la Sierra (Madrid, Spain) (Ávila and Zamora 2015) or Kosovo (Pristine) (Qerimi et al. 2020), as high-potential areas for solar production due to their high population density, and because of solar PV plays a vital role in energy transition of urban energy systems (Zhu et al. 2023).
Buildings are responsible for around 40% of the European Union's (EU) energy consumption, with residential buildings accounting for 27% of the EU's final energy consumption in 2020. To make this consumption as renewable as possible, one of the alternative is to generate part of the electrical demand by installing photovoltaic panels (PV) on the rooftops or façades of buildings. In addition, the way solar systems are used in buildings has changed. Buildings are no longer designed with only passive solar systems, such as windows and sunspaces, or active solar systems, such as PV or solar collectors, as new buildings integrate technologies of both types. They can be energy efficient, solar heated and cooled, and powered by PV systems; they are, in short, "solar buildings".
Calculating the solar potential requires a feasibility analysis taking into account various environmental and technical factors, which have been studied in several works. For example, Farrell et al. (2020) assessed the recycling routes for implementing the circular economy on the wastes of PV modules. Lobaccaro et al. (2019) analyzed the barriers and opportunities for active solar systems in urban planning to stimulate successful practices. Different models and methods can estimate the PV potential, including the use of a Geographic Information System (GIS). This tool has been used in various studies, such as in Ahmetovíc et al. (2022) where combining the data obtained from PVGIS with Fuzzy Analytical Hierarchical Processes the best location to implement PV system is chosen according to eight criteria. Pinna and Massidda (2022) presents a method to estimate the rooftop PV system power capacity in Sardinia based on this software. Thotakura et al. (2020) validated a grid-connected rooftop solar photovoltaic (PV) plant in Serbia by comparing the monitored data with the one obtained by, among others, the PVGIS simulation. A complete systematic review of various developed methodologies for PV potential assessment in buildings is analyzed by Fakharian et al. (2021) where GIS software appears as a promising tool. Mohajeri et al. (2018) employs Machine Learning to classify urban characteristics for solar applications, and includes the impacts of different roof shapes on annual solar PV electricity production, to analyze the PV potential of an area.
PV installations produce electricity using various configurations, and current policies promote combining them with other technologies such as heat pumps or solar thermal collectors. Hybrid solar photovoltaic-electrical energy storage systems are reviewed for building in (Liu et al. 2019). Herrando et al. (2019) analyzed the possibilities of using solar thermal collectors to meet the heating, cooling and domestic hot water (DHW) demands of a dwelling (ST, PV/T, and PV with heat pumps). The integration of hybrid and organic photovoltaics in greenhouses are studied in (La Notte et al. 2020) to promote sustainable, self-powered and smart greenhouses.
There are also centralized heating and/or cooling systems based on a network, which provide heating, cooling and DHW, and can be linked to renewable generators or solar fields. They are also known as district heating and cooling systems and have the great advantage that, by supplying a large number of users, they have a more uniform demand, which allows the generating equipment to operate continuously. From an energy and environmental perspective, district networks are a very effective alternative for reducing primary energy consumption and emissions, especially when renewable resources are used.
In urban locations, where there are not many lands to implement solar fields, it is necessary to look for other solutions, since it is usually easier to have many small solar installations distributed on the roofs of buildings, rather than large centralized solar collection fields, such as in energy communities. Energy communities reduce costs due to economies of scale, and the shorter distances between grids and consumption are also an advantage.
PV installations and the combinations of technologies in which they are included are suitable to be introduced into energy communities. In the European Union (EU) energy communities are gaining increasing attention as a way to promote renewable energy, energy efficiency, and local participation in the energy transition. These communities are defined as groups of individuals, households, or organizations who jointly own, develop, manage, and/or use renewable energy sources and energy-efficient technologies to satisfy their own energy needs and possibly sell any excess energy to the grid.
Currently, energy communities in the EU are subject to the Renewable Energy Directive (RED II), which was adopted in 2018 and came into force in 2019. The directive introduces provisions on self-consumption and renewable energy communities, providing legal recognition and support for energy communities. In addition, the EU Clean Energy Package, which was adopted in 2019, further promotes the role of energy communities in the EU's energy transition.
Several EU countries have already taken steps to promote energy communities. For example, Germany, Austria, and Denmark have established legal frameworks and financial incentives to support the development of energy communities. In Germany, the Renewable Energy Sources Act was amended in 2021 to improve the regulatory framework for energy communities, including simplifying the registration process and reducing administrative burdens. In France, the Energy Transition Law of 2015 introduced the concept of "energy cooperatives" and created a legal framework for their establishment.
Taking into account this European benchmark, the concept of energy community has been widely studied and applied in different studies, such as, Conte et al. (2022), Bianchi et al. (2023), Chaudrhry et al. (2022) and Sokolowski (2020), which focus on the implementation and current EU policies. Otamendi-Irizar et al. (2022), Nagpal et al. (2022) and Marionopoulos et al. (2018) work on the same topic but focusing on their corresponding local energy communities, and Frieden et al. (2019), Jeriha (n.d.) and Gjorgievski et al. (2021), analyses the concept of collective self-consumption from a techno- economic and regulatory point of view.
The impact of energy communities in Spain compared to the rest of the cities in the European Union is minor, although it has a great potential. Currently, there are 290 projects underway in Spain, of which 255 are renewable energy communities that generate electricity with an installed capacity of 51,970 kW according to the Institute for Energy Diversification and Saving (IDAE). The regulatory framework for energy communities is defined by Law 24/2013, on the Electricity Sector (LSE), which establishes the legal framework for producing, transporting, distributing, and commercializing electricity, including the regulation of self- consumption and the participation of citizens in the electricity system. Royal Decree 244/2019, regulates the administrative, technical and economic conditions of self-consumption of electric power, as well as its administrative registration. The "National Integrated Energy and Climate Plan" (PNIEC) recognizes the potential of energy communities to help Spain achieving energy and climate objectives, and includes a number of measures to support their development as it does the “Long-term Decarbonization Strategy 2050”.
Several studies have been carried out focusing on the Spanish context. Among others, the objective of Manso-Burgos et al. (2022) is to evaluate the technical and economic feasibility of local energy communities and to propose optimization strategies that could be implemented in Valencia. Gallego-Castillo et al. (2021) examine the current legal framework for energy communities in Spain, as well as the potential for self-consumption of renewable energy within these communities. Pinto et al. (2022) explores the application of energy communities to optimize polygeneration systems in residential buildings, focusing on a case study in Zaragoza.
According to the literature review, the PV potential of a city can be fully detailed through a GIS analysis and considering the climate characteristics of the place. Because of geographical and technical reasons, energy communities are a good option to implement green resources generation to cover energy demands and to make a community participation. Because of that, EU members are currently working on directives which detail their design and execution, although Spain still seems to have a research vacuum in energy communities application despite its solar potential. Therefore, this work assesses the solar potential of the city of Vitoria-Gasteiz, which has suitable characteristics for installing PV solar panels and creating different energy communities in the area. It also analyses the option of implementing an energy community including the rooftop of the Mercedes-Benz building in Vitoria-Gasteiz, which is not inside the public house-stock, but seems to have great solar potential on its rooftop.
Consequently, in order to fully comprehend the PV capacity of public buildings and the viability of implementing energy communities between them and with nearby structures, it is crucial to do an analysis as accurate as the shown here. Additionally, it examines whether similar actions or outcomes could be achieved in other cities with environments and geographies similar those of Vitoria-Gasteiz.
This work deals with the continuation of the work carried out in the international conference ECOS2023. In this study, the possibilities of implementing energy communities with PV systems in 31 public-housing buildings in Vitoria-Gasteiz (north of Spain) are analyzed. As a whole, 134 sections of this 31 public-housing were taken into account in order to consider a radius of 500 meters from the center of the energy community production-point (see Fig. 1(a)), as said in the Royal Decree 244/2019. Moreover, as the allowed radius has recently been extended to 2 km, this new situation has been also analyzed gathering all public-buildings in just 3 energy communities, see Fig. 1(b).
As a novelty and because of geographical conditions, one of the selected energy communities includes the rooftop of Mercedes-Benz manufacturing building. Therefore, such energy community has been deeply analyzed to include the possibility of renting the roof of the factory.
According to previous researches, the average age of the buildings is of 16 years old and 84% of them have a D or E energy-label, retrieved from PLAN ZERO PLANA plan.
The methodology used in this study follows the steps depicted in Fig. 2, which are afterwards deeply explained:
3.1 Data importation from GEOEUSKADI, public-building stock and QGIS.
3.2 Calculation of rooftops’ Incoming Solar Radiation.
- Discarding the non-useful rooftops’ areas, using C.1-C.5 criteria.
- Calculating the PV capacity of rooftops (monthly and hourly).
3.3. Creating different energy communities and estimating the Installed Peak Power.
-
With 500 m radius criteria
-
With 2000 m radius criteria
-
Analyzing the special case with Mercedes-Benz factory.
-
Estimating the environmental and economic savings.
3.1 Data collection
As mentioned, and because of its versatility, the QGIS (Quantum Geographic Information System) Georeferencing Software was used to account the PV potential of the city. This software handles and organizes large amounts of data, enabling data storage, manipulation, analysis and modelling. Additionally, topographic data, including LIDAR data, were obtained from GeoEuskadi to include cadastral information of buildings, urban and rural areas, infrastructure, and municipal boundaries. Digital Surface Model (DSM) sheets were also consider to cover the information of various elements of the Earth's surface, buildings, vegetation, infrastructure and soil.
3.2 Data processing
After importing and assigning the topographic data to the QGIS layers, the potential of the incoming solar radiation was calculated over the whole year 2018, and monthly layers were obtained with the radiation information. Figure 3(a) depicts, as an example, the accumulated solar radiation during August in all the rooftops of the corresponding area of Vitoria-Gasteiz.
For each MSD sheet, and to obtain the accurate data for the study, the QGIS raster was cut considering only the specific public-housing rooftops. In addition, as not all roofs are suitable for implementing photovoltaic systems, non-useful areas were discarded according to the following main criteria, based on Delphine Khana’s study (n.d.):
The rooftops must have a minimum of 65 kWh/m2 of solar radiation accumulated over a period of one month.
C. 1) The slope of the rooftop must not exceed 45 degrees, as steeper slopes receive less sunlight. The 45 degree limit is determined according to the latitude of the city of Vitoria-Gasteiz (42.85°) being the optimal inclination ± 10° relative to the local latitude.
C. 2) Rooftops facing north and those receiving less sunlight, because of the shadows, are not suitable.
C. 3) Rooftops with an inadequate area of more than 25% are excluded.
C. 4) Rooftops with less than 30% optimal surface area and less than 100 m2 of optimal surface area are eliminated.
C. 5) Areas with less than 10 m2 of suitable space are excluded.
Accordingly, Fig. 3(b) shows the accumulated solar radiation in August in the suitable rooftops areas of public buildings. Besides, after filtering the reliable solar radiation reaching the roofs of the public buildings in Vitoria-Gasteiz, we assume that only 25% of the calculated area can be used to implement photovoltaic panels, because of the technical issues associated with shadows between panels, structures, wiring, etc. In addition, photovoltaic panels were considered to have an efficiency of 15% and a Performance Ratio (PR) of 86% (Khana n.d.). Consequently, the PV capacity is obtained with the optimal surface (𝑆𝑢𝑟𝑓𝑜𝑝𝑡) and the mean radiation (𝑅𝑎𝑑𝑚𝑒𝑎𝑛) of each public building.
𝑃𝑉 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 (k𝑊ℎ) =\(\text{P}{\text{V}}_{\text{c}}\)= 𝑆𝑢𝑟𝑓𝑜𝑝𝑡 · 0.25 · 𝑅𝑎𝑑𝑚𝑒𝑎𝑛 · 0.15 · 0.86(1)
In order to do a deep analysis, an hour-by-hour analysis is carried on. However, as the consumption data of households are not available in an hour-by-hour basis (but only in a yearly base), the consumption profile proposed by the study of Aberilla et al. (2020) has been adapted to each rooftop our case study during the whole year and compared with the hourly PV production.
3.3 Energy communities
According to the PV monthly and hourly capacity, at first, seven energy communities have been proposed (already shown in Fig. 1(a)) considering the maximum optimal-surface of public-housing rooftops with a radius of 500 meters and, secondly, with 2 km (see Fig. 1(b)).
As a special case, one of the energy communities contains the empty rooftop of the Mercedes-Benz factory building (see Fig. 4), so the possibility of including such roof for electricity PV production was also analyzed. To do that, the previous criteria (C.1-C.5) has been extended to this private-roof, in order to calculate the accumulated solar radiation in each month and hour of the year. Figure 5 depicts, as an example, the available accumulated solar radiation in the factory’s rooftop during August.
Accordingly and considering the RD 14/2020, it is assumed that the Equivalent Operating Hours (EOH) of each PV installation will be around 1250 h. Thus, the peak power of each energy community is obtained by the following expression:
$$\text{I}\text{n}\text{s}\text{t}\text{a}\text{l}\text{l}\text{a}\text{t}\text{i}\text{o}\text{n} \text{P}\text{e}\text{a}\text{k} \text{P}\text{o}\text{w}\text{e}\text{r} \left(\text{k}\text{W}\text{p}\right)=\text{I}\text{P}\text{P}=\frac{\text{P}\text{V} \text{c}\text{a}\text{p}\text{a}\text{c}\text{i}\text{t}\text{y} (\text{K}\text{W}\text{h}/\text{y}\text{e}\text{a}\text{r})}{\text{E}\text{O}\text{H} \left(\text{h}\text{o}\text{u}\text{r}\text{s}\right)}$$
2
The PV capacity and Installation Peak Power values allow us doing a very simple economic and environmental analysis:
-
The economic analysis is based on a report made by International Renewable Energy Agency (IRENA) called “Renewable Power Generation Costs in 2021”, which says that the average cost of a PV installation is 875 $/kW (accordingly, 788.44 €/kW). Therefore, to calculate the simple Payback (PB), a unit cost of electricity of \({\text{c}}_{\text{e}}=\) 0.258 €/kWh was assumed (according to the Spanish government) with the following expression:
$$\text{P}\text{B} \left(\text{y}\text{e}\text{a}\text{r}\right)=\frac{\text{I}\text{n}\text{s}\text{t}\text{a}\text{l}\text{l}\text{a}\text{t}\text{i}\text{o}{\text{n}}_{\text{c}\text{o}\text{s}\text{t}} \left(\frac{\text{€}}{\text{k}\text{W}}\right)·\text{I}\text{P}\text{P} \left({\text{k}\text{W}}_{\text{p}}\right)}{\text{C}\text{o}\text{m}\text{p}\text{e}\text{n}\text{s}\text{a}\text{t}\text{e}{\text{d}}_{\text{E}}\left(\frac{\text{€}}{\text{k}\text{W}\text{h}}\right)·\text{P}{\text{V}}_{\text{c}}\left(\frac{\text{k}\text{W}\text{h}}{\text{y}\text{e}\text{a}\text{r}}\right)+{\text{c}}_{\text{e}}\left(\text{€}/\text{k}\text{W}\text{h}\right)·\text{P}{\text{V}}_{\text{c}}\left(\frac{\text{k}\text{W}\text{h}}{\text{y}\text{e}\text{a}\text{r}}\right)}$$
3
-
Where:
-
Installationcost (€/kWh), is the cost of the PV installation
-
IPP (kWp), is the Installation Peak Power
-
CompensatedE (€/kWh), is the price of the compensated electricity
-
PVC (kWh/year), is the PV capacity during a year
-
Ce (€/kWh), is the unit cost of the electricity
-
For the environmental analysis, an emission factor of 0.25 kgCO2/kWh was taken into account according to IDAE and the next equation was solved:
$${\text{C}\text{O}}_{2}\text{s}\text{a}\text{v}\text{i}\text{n}\text{g}\text{s}=\text{P}\text{V} \text{c}\text{a}\text{p}\text{a}\text{c}\text{i}\text{t}\text{y}·\text{E}\text{m}\text{i}\text{s}\text{s}\text{i}\text{o}\text{n} \text{f}\text{a}\text{c}\text{t}\text{o}\text{r}$$
4
This section contains the main findings of the analysis regarding the (1) public-housing buildings’ optimal surface area and overall PV potential, (2) the analysis of the energy communities with PV electric supply and the (3) special case of the energy community with the PV supply of Mercedes-Benz factory’s roof.
4.1. Public-housing Buildings
As said, to identify suitable areas of public-housing rooftops, a detailed analysis was conducted building by building based on QGIS Georeferencing Software and the previous criteria (C.1-C.5), and, then, the overall values were calculated. As a result, only 47.1% of the total roof capacity of public housing was found to be suitable for installing PV panels, see Fig. 6 (a).
Besides, it is considered that (1) only a maximum of 25% of the optimal surface can be covered with PV panels (to avoid self-shading, to consider the space for maintenance, etc.), and (2) the performance of the PV panels is estimated in 15% (with a Performance Ratio of 86%). Therefore, the Fig. 6 (b) shows the monthly PV capacity in all public buildings of Vitoria-Gasteiz, that, as expected, the highest production months are the ones related to spring and summer period.
4.2. Energy Communities with PV Electric Supply
As mentioned above, this analysis have been done twice: firstly, considering the energy communities with a radius of 500 m and, secondly, with 2 km.
4.2.1 Energy Communities with 500 m radius
The previous rooftop results were accumulated according to the energy community to which each building belongs, trying to group the maximum capacity of public-housing in each energy community. In total, seven energy communities were identified as shown in Fig. 1 (a). The following step calculates the percentage of electricity that could be produced and self-consumed in each energy community in a monthly and an hourly basis.
As the analysis of the seven energy communities concludes similarly, only the results of the 4th community will be discussed (shown in Fig. 7(a)), which contains 458 households.
As a first analysis, the monthly production was compared with the electric consumption and depicted in Fig. 7 (b), where it is shown that only the 44% of the consumption could be meet with PV local production, while the rest should be purchased from the grid, exactly 437 MWh.
Even if monthly analysis is always less precise than the hourly analysis, it helps to make a first screening of the potential, indicating that during the peak months of the year (May, June and July) PV energy community concept could be a viable alternative worth considering. Consequently, this analysis must be extended to an hour-by-hour analysis (or even a shorter period), in order to consider the real match between electricity consumption and production, taking into account the in situ local radiation. Therefore, an hour-by-hour analysis of the 4th energy community appears in Fig. 8, which, because of space reasons, shows only one day per each season.
According to the hourly results, even in the summer months, PV production does not cover energy consumption throughout the day, although there are time zones with surplus and sales to the grid. The most favorable months in this 4th energy community are June and July, when the energy purchased from the grid will be less than 600 kWh, which is equivalent to less than 1.31 kWh per day and per household.
4.2.2. Energy-communities with 2 km radius
Additionally, the analysis is repeated considering the 2 km radius currently accepted and proposing 3 new energy communities (see Fig. 1(b)).
The monthly first analysis shows analogous results as none of the energy communities covers the electricity demand of public-buildings neither on summer period, see Fig. 9.
The 2nd energy community with 2 km radius (Fig. 9 (b)) contains the previous 4th energy community with 500 m depicted in Fig. 7. In this specific case, the percentage of the electric consumption that could be covered by PV local production decreases from 44–33%, and the electrical demand that should be purchased from the grid arrives to 1599 MWh.
The results of the hour-by-hour analysis are analogous to the 500-meter situation even if, as it is obvious, the absolute result depends on the number of householders and the optimal surface of the rooftops included in the radius. Nevertheless, as a whole, public residential building are not capable of meeting their electricity demand with their own local PV generation. Because of that, other roofs should be included in the analysis.
4.3. Specific Case of an Energy Community with a factory
According to the previous results, this section analyzes the scenario of including the roof of Mercedes-Benz factory in one of the energy communities (according to the case of 500 m radius and the one of 2 km). In addition, an environmental and economic analysis is done.
4.3.1. Specific Case of an Energy Community: 500 meter radius
The energy community with 500 m radius that includes also the building of Mercedes-Benz factory is numbered as 7th energy community and contains 630 householders. Consequently, the same previous process has been repeated in this roof in order to estimate its PV capacity. Accordingly, the histogram of solar radiation in August of the Mercedes-Benz building, shown in Fig. 10 (a), reflects that the most common value of accumulated radiation in such month is 240 kWh/m2. Therefore, and considering the C.1-C.5 criteria, the optimal surface for implementing PV systems accounts for the 77% of the total area, see Fig. 10 (b).
Surprisingly, the optimal surface of this factory is 3.75 times greater than the overall public-housing rooftop optimal surface. Hence, the factory has a big potential for implementing PV local systems.
The PV capacity of the 7th energy community can be analyzed without considering the factory’s rooftop potential (as in the preceding analysis) or considering it, see Fig. 11(a) and Fig. 11(b).
In the first case, as justify in the previous section, there is a need to purchase electricity from the grid in order to supply all the electric demand required by the householders. On the contrary, when the factory’s rooftop is considered, a remarkable electric surplus appeared during the whole year that could be used in further applications. The significant disparity between the purchased energy without accounting for the factory's PV generation and the surplus energy with accounting for it is depicted graphically in Fig. 11.
Following the previous methodology, an hour-by-hour analysis of this energy community is carried on obtaining the graphs of Fig. 12.
As it can be seen, when PV production exists, there is almost always a surplus. Because of the Spanish regulation, the energy discharged to the grid can be compensated at half the price of the energy purchased from the grid, so, introducing batteries may be a good proposition for a better use of energy.
4.3.2. Specific Case of an Energy Community: 2 km radius
With the 2 km radius criteria, the profiles of the PV production and the consumption increases a little bit as it can be seen in Fig. 13, which analyses the consumption and PV production of the energy community (top part) and the energy exchange with the grid (bottom part).
This first analysis has been made in a monthly basis to compare it with the 500 m radius situation. In consequence, contrary to the 500 m case, in the winter months (December and January) there is not an energy surplus, so an isolated installation could not be considered and the electricity should be purchased from the grid (see Table 1).
Table 1 Electric surplus in Mercedes-Benz Energy Community (M.B. E.C.) (with 500m and 2 km)
The hourly results are very similar to those for the 500 meters radius; see Fig. 14, although there are two hours less each day without electric surplus.
Therefore, the energy consumption increases proportionally more than the PV production when the radius of the energy community increases. Nevertheless, when Mercedes-Benz factory is included, almost every month has electric surplus.
4.3.3. Environmental and economic analysis
Considering the case where the factory’s rooftop participates in the electric generation, the Installation Peak Power obtained from Eq. (2) with a radius of 500 meters has a value of 5,118 kWp, and with a radius of 2 km, 5,534 kWp.
If the electric surplus is incorporated to the grid, and assuming a compensation price of 0.05 €/kWh according to Selectra, the simple Payback of Eq. (3) gives a value of 2.05 years for the case of 500 meter radius and almost the same (2.04 years) for the 2 km radius. The environmental improvement can be calculated, among others, considering the kg of CO2 that are no longer emitted into the atmosphere, which account for 1,599 tons of CO2 avoided per year for the first situation of 500 meter radius and 1,729 tons for the second scenario, if the whole photovoltaic installation is set up.
Analyzing these results, this energy community seems to be very feasible, but as it only considers the consumptions of public residential buildings, a good possibility would be to include the production and the consumption of other private buildings inside the area of these energy communities.
This work extends the research carried out on the photovoltaic potential in public-housing buildings in the city of Vitoria-Gasteiz (northern Spain), implementing the results in a series of energy communities (with 500 m and 2 km radius) and including an hour by hour analysis.
Because of that, the first step calculates the PV capacity of each rooftop taking into account five criteria for a comprehensive and realistic research. As a whole, only the 47% of the total surface is available for implementing PV panels. If this potential is compared with the electric demand of each household, it is shown that there is not enough on-site generation for self-consumption and that it is necessary to obtain it from other resources.
Therefore, the local analysis per roof has been expanded to the perspective of energy communities, with the aim of analyzing whether self-consumption can be improved by including several buildings. As a first step, energy communities considering only public-housing in a radius of 500 meters were analyzed, even if currently the allowed radius has been extended to 2 km, to ascertain how to implement an energy community of public buildings under such a severe restriction. In addition, energy communities with a radius of 2 km were also analyzed to compare those two scenarios.
According to the results of the first scenario (500 meters), seven energy communities are defined but no one of them supplies the completely electric demand during the year. As expected, and for almost all the defined energy communities, the PV contribution in June and July supplies the 77% of the electric demand, but the contribution in December and January barely reaches the 10%. This monthly analysis was the preliminary step to a more comprehensive analysis on an hourly basis. Although the electricity consumption of each instant is unknown (due to confidentiality reasons), an hourly consumption profile has been adapted from literature and compared with the instantaneous PV production. Results are a bit stricter than monthly ones, as on June the PV production supplies almost the same percentage of the energy demand as the previous analysis, but on January, for example, the supply increases from 10–12%.
The results of the second scenario (2 km) are similar, as the energy communities do not provide the complete electric demand during the year. Overall, in the case of considering only public-housing, increasing the radius of the energy community do not enhance the situation. Hence, further analysis should be done involving private residential houses or tertiary buildings in the energy communities.
Bearing this in mind and as there is a special case of an energy community, a deeper analysis was done including the empty rooftop of the Mercedes-Benz factory. Adding this roof increases by more than 400% the overall optimal surface of the public-housing area. Consequently, such energy community could have had an annual electricity surplus of 5,323 MWh with a simple payback time of 2.05 years considering the 500 radius and an annual electric surplus of 4,369 MWh and a simple payback of 2.04 years with 2 km radius. Therefore, including this factory seems promising in terms of PV generation and could supply more buildings apart from public housing, as the compensation of surpluses does not seem a priori a good business. In this case, the increasing of the radius of the energy community is a more suitable idea, because there is still a surplus energy that can assess the energy demand of more buildings.
A future analysis is related to the hybridization of photovoltaic systems and heat pump technology in order to supply not only electricity, but also heating and cooling. Besides, to improve the situation of energy communities in Spain, it would be a great contribution to the promotion of this type of energy self-consumption, especially in the city of Vitoria- Gasteiz, known as the Green Capital. Nevertheless, as the Spanish government states, active participation from citizens is very important, as well as collaboration between this individual citizens, SMEs and local authorities.
Acknowledgements: The authors would like to thank the Basque Government's Laboratory for the Quality Control of Buildings and ALOKABIDE SA for the provided information and the help given for this study. In addition, we would like to thank personally Jose Maria Sala Lizarraga, Pablo Hernandez, Juan María Hidalgo Betanzos and Imanol Ruiz de Vergara Ruiz de Azua for being a source of contrast and wisdom for this paper. Finally, Mikel Garro-Aguilar, who is financially supported by a scholarship provided by the same, would like to thank the University of the Basque Country for its support.
- Eusko Jaurlaritza. Basque Government. Economic Development and Competitiveness Department. EUSKADI 2030 Energy Strategy. (in Spanish)
- Gassar AAA, Cha SH (2021) Review of geographic information systems-based rooftop solar photovoltaic potential estimation approaches at urban scales. Appl Energy 291:116817. https://doi.org/10.1016/j.apenergy.2021.116817
- Ávila AMM, Zamora AB (2015) Estudio del potencial fotovoltaico sobre los tejados del núcleo. urbano de Miraflores de la Sierra. Ciemat
- Qerimi D, Dimitrieska C, Vasilevska S, Rrecaj AA (2020) Modeling of the solar thermal energy use in urban areas. Civil Eng J 6(7):1349–1367
- Zhu R, Kwan MP, Perera ATD, Fan H, Yang B, Chen B, …, Yan J (2023) GIScience can facilitate the development of solar cities for energy transition. Adv Appl Energy, 100129
- European Commission (2021) Making our homes and buildings fit for a greener future. 10.2775/03938
- Eurostat (2022) “Energy consumption in households,” [Online]. Available: https://ec.europa.eu/eurostat/statistics- explained/index.php?title = Energy_consumption_in_households#Energy_products_used_in_the_residential_secto r%0Ahttps://ec.europa.eu/eurostat/statistics- explained/index.php?title = Energy_consumption_in_households#Energy
- Farrell CC, Osman AI, Doherty R, Saad M, Zhang X, Murphy A, …, Rooney DW (2020) Technical challenges and opportunities in realising a circular economy for waste photovoltaic modules. Renew Sustain Energy Rev 128:109911
- Lobaccaro G, Croce S, Lindkvist C, Probst MM, Scognamiglio A, Dahlberg J, …, Wall M (2019) A cross-country perspective on solar energy in urban planning: Lessons learned from international case studies. Renew Sustain Energy Rev 108:209–237
- Ahmetović H, Nukić E, Hivziefendić J, Šarić M, Ponjavić M (2022), March PV system site selection using PVGIS and Fuzzy AHP. In 2022 21st International Symposium INFOTEH-JAHORINA (INFOTEH) (pp. 1–6). IEEE
- Pinna A, Massidda L (2022) A Complete and High-Resolution Estimate of Sardinia’s Rooftop Photovoltaic Potential. Appl Sci 13(1):7
- Thotakura S, Kondamudi SC, Xavier JF, Quanjin M, Reddy GR, Gangwar P, Davuluri SL (2020) Operational performance of megawatt-scale grid integrated rooftop solar PV system in tropical wet and dry climates of India. Case Stud Therm Eng 18:100602
- Fakhraian E, Forment MA, Dalmau FV, Nameni A, Guerrero MJC (2021) Determination of the urban rooftop photovoltaic potential: A state of the art. Energy Rep 7:176–185
- Mohajeri N, Assouline D, Guiboud B, Bill A, Gudmundsson A, Scartezzini J-L (2018) A city- scale roof shape classification using machine learning for solar energy applications. Renewable Energy 121:81–93. https://doi.org/10.1016/j.renene.2017.12.096
- Liu J, Chen X, Cao S, Yang H (2019) Overview on hybrid solar photovoltaic-electrical energy storage technologies for power supply to buildings. Energy Conv Manag 187:103–121
- Herrando M, Pantaleo AM, Wang K, Markides CN (2019) Solar combined cooling, heating and power systems based on hybrid PVT, PV or solar-thermal collectors for building applications. Renewable Energy 143:637–647
- La Notte L, Giordano L, Calabrò E, Bedini R, Colla G, Puglisi G, Reale A (2020) Hybrid and organic photovoltaics for greenhouse applications. Appl Energy 278:115582
- Renewable Energy – Recast to 2030 (RED II). (n.d.). Retrieved March 20 (2023) from https://joint-research- centre.ec.europa.eu/welcome-jec-website/reference-regulatory-framework/renewable-energy-recast-2030-red- ii_en
- Directorate-General for Energy (European Commission) (2019) Clean energy for all Europeans. Publications Office of the European Union. https://data.europa.eu/doi/10.2833/9937
- Vizzuality (2023) (n.d.). Renewable Energy Sources Act (EEG, latest version EEG 2022)—Germany—Climate Change Laws of the World. Retrieved March 20, from https://climate- laws.org/geographies/germany/laws/renewable-energy-sources-act-eeg-latest-version-eeg-2022
- Vizzuality (2023) (n.d.). Law no. 2015 – 992 on Energy Transition for Green Growth (Energy Transition Law)— France—Climate Change Laws of the World. Retrieved March 20, from https://climate- laws.org/geographies/france/laws/law-no-2015-992-on-energy-transition-for-green-growth-energy-transition-law
- Conte F, D’Antoni F, Natrella G, Merone M (2022) A new hybrid AI optimal management method for renewable energy communities. Energy and AI 10:100197. https://doi.org/10.1016/j.egyai.2022.100197
- Bianchi FR, Bosio B, Conte F, Massucco S, Mosaico G, Natrella G, Saviozzi M (2023) Modelling and optimal management of renewable energy communities using reversible solid oxide cells. Appl Energy 334:120657. https://doi.org/10.1016/j.apenergy.2023.120657
- Chaudhry S, Surmann A, Kühnbach M, Pierie F (2022) Renewable Energy Communities as Modes of Collective Prosumership: A Multi-Disciplinary Assessment Part II—Case Study. Energies 15(23) Article 23. https://doi.org/10.3390/en15238936
- Sokołowski MM (2020) Renewable and citizen energy communities in the European Union: How (not) to regulate community energy in national laws and policies. J Energy Nat Resour Law 38(3):289–304. https://doi.org/10.1080/02646811.2020.1759247
- Otamendi-Irizar I, Grijalba O, Arias A, Pennese C, Hernández R (2022) How can local energy communities promote sustainable development in European cities? Energy Res Social Sci 84:102363. https://doi.org/10.1016/j.erss.2021.102363
- Nagpal H, Avramidis I-I, Capitanescu F, Madureira AG (2022) Local Energy Communities in Service of Sustainability and Grid Flexibility Provision: Hierarchical Management of Shared Energy Storage. IEEE Trans Sustain Energy 13(3):1523–1535. https://doi.org/10.1109/TSTE.2022.3157193
- Marinopoulos A, Vasiljevska J, Mengolini A (2018) Local energy communities: An insight from European smart grid projects. AIM. https://doi.org/10.34890/424
- Frieden D, Tuerk A, Roberts J, D’Herbemont S, Gubina AF, Komel B (2019) Overview of emerging regulatory frameworks on collective self-consumption and energy communities in Europe. 2019 16th International Conference on the European Energy Market (EEM), 1–6. https://doi.org/10.1109/EEM.2019.8916222
- Jeriha J (n.d.) (ed) Collective self-consumption and energy communities
- Gjorgievski VZ, Cundeva S, Georghiou GE (2021) Social arrangements, technical designs and impacts of energy communities: A review. Renewable Energy 169:1138–1156. https://doi.org/10.1016/j.renene.2021.01.078
- Comunidades (2023) Energéticas | Idae. (n.d.). Retrieved March 20, from https://www.idae.es/ayudas-y- financiacion/comunidades-energeticas
- BOE-A-2013-13645 Ley 24/2013, de 26 de diciembre, del Sector Eléctrico. (n.d.). Retrieved March 21 (2023) from https://www.boe.es/buscar/act.php?id=BOE-A-2013-13645&p=20221019&tn=0
- Real Decreto 244 (2019) / de 5 de abril, por el que se regulan las condiciones administrativas, técnicas y económicas del autoconsumo de energía eléctrica, Pub. L. No. Real Decreto 244/2019, BOE-A-2019-5089 35674 (2019). https://www.boe.es/eli/es/rd/2019/04/05/244
- Plan Nacional Integrado de Energía y Clima (PNIEC) 2021–2030. (n.d.). Retrieved March 6 (2023) from https://www.miteco.gob.es/es/prensa/pniec.aspx
- Long Term Decarbonisation Strategy in Spanish, Estrategia de Descarbonización a Largo Plazo 2050. (n. d.). Retrievered March 6, 2023, from https://www.miteco.gob.es/es/prensa/documentoelp_tcm30-516109.pdf
- Manso-Burgos Á, Ribó-Pérez D, Gómez-Navarro T, Alcázar-Ortega M (2022) Local energy communities modelling and optimisation considering storage, demand configuration and sharing strategies: A case study in Valencia (Spain). Energy Rep 8:10395–10408. https://doi.org/10.1016/j.egyr.2022.08.181
- Gallego-Castillo C, Heleno M, Victoria M (2021) Self-consumption for energy communities in Spain: A regional analysis under the new legal framework. Energy Policy 150:112144. https://doi.org/10.1016/j.enpol.2021.112144
- Pinto ES, Serra LM, Lázaro A (2022) Energy communities approach applied to optimize polygeneration systems in residential buildings: Case study in Zaragoza, Spain. Sustainable Cities and Society 82:103885. https://doi.org/10.1016/j.scs.2022.103885
- : The 36th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. Universidad de Las Palmas de Gran Canaria (ULPGC)
- Congreso de los Diputados - Canal Parlamento (Director) (2022), November 2 Comisión de Transición Ecológica y Reto Demográfico (02/11/2022). https://www.youtube.com/watch?v=ZZsZyRSMV74
- Plan de Ciencia, Tecnología e Innovación—PLAN ZERO PLANA (2022) https://www.alokabide.euskadi.eus/plan-de-ciencia-tecnologia-e-innovacion-plan-zero-plana/
- GeoEuskadi (2023) Datu Espazialen Egitura—Euskadiko DEA. (n.d.). Retrieved March 6, from https://www.geo.euskadi.eus/webgeo00-inicio/eu
- Estimar el potencial de energía solar | Learn ArcGIS. (n. d.). Retrieved March 6 (2023) from https://learn.arcgis.com/es/projects/estimate-solar-power-potential/
- Aberilla JM, Gallego-Schmid A, Stamford L, Azapagic A (2020) Design and environmental sustainability assessment of small-scale off-grid energy systems for remote rural communities. Appl Energy 258:114004. https://doi.org/10.1016/j.apenergy.2019.114004
- BOE.es—DOGV-r-2020-90356 Decreto-ley 14/2020, de 7 de agosto, del Consell, de medidas para acelerar la implantación de instalaciones para el aprovechamiento de las energías renovables por la emergencia climática y la necesidad de la urgente reactivación económica. (n.d.). Retrieved March 23 (2023) from https://www.boe.es/buscar/doc.php?id=DOGV-r-2020-90356
- Renewable Power Generation Costs in 2021 (2022), July 13 https://www.irena.org/publications/2022/Jul/Renewable-Power-Generation-Costs-in-2021
- PRECIO NETO DE LA ELECTRICIDAD PARA USO DOMÉSTICO Y USO INDUSTRIAL. (n.d.)
- FACTORES DE CONVERSIÓN EN EL CÁLCULO DE AHORRO DE ENERGÍA Y REDUCCIÓN DE EMISIONES (2023) DE CO2 (n.d.). Gob.es. Retrieved March 23, from https://sede.idae.gob.es/lang/extras/tramites- servicios/2021/MOVES_Proyectos_Singulares_II/Factores_de_conversion_ahorros_y_emisiones_de_CO2.pdf
- Tarifas de compensación de excedentes para placas solares. (n.d.). Selectra. Retrieved March 23 (2023) from https://selectra.es/autoconsumo/info/tarifas
No competing interests reported.