Photo credits Instagram/romandeenergie

The sun-sational revolution
towards alternative energy

Multi-scale analysis of the exhaustion of the photovoltaic potential in Switzerland
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Installed Plants

Power of plants

Current Energy Output (GWh/a)


Switzerland’s electricity consumption in the year 2021 amounts to 57 TWh/a, of which roughly 80% can already be attributed to renewable energy sources. However, Switzerland’s electricity consumption is projected to grow to 84 TWh/a until the year 2050 due to various factors such as population growth, electrification of previously fossil-fuel powered industries as well as technological advancements such as the widespread adoption of electric vehicles or artificial intelligence. This increased demand will not be able to be covered by nuclear or hydropower, as Switzerland plans a gradual phase-out of nuclear energy and since the potential of hydropower has largely been exhausted due to conflicting concerns regarding ecology and landscape protection.

Energy Mix

That is where solar energy comes into play. Compared to nuclear power, there are no concerns of devastating accidents or radioactive waste management and the impact of the plants on ecosystems and nature is much less significant as opposed to hydropower plants. As of 2021, solar energy currently accounts for just 5% of Switzerland’s annual electricity consumption, which means that Switzerland is (solar-)eclipsed in this regard by neighboring countries such as Germany or Italy. Even though the installed power of all photovoltaic plants already exceeds the power of Switzerland’s four active nuclear power plants, there is still much room to grow. Studies show that the combined photovoltaic potential of the roofs and facades of buildings in Switzerland amounts to 85 TWh/a, which means that the predicted electricity consumption for 2050 could theoretically be fully covered by installing photovoltaic plants on all suitable roofs and facades in Switzerland. However, only roughly 4% of this potential is currently exhausted.

Research Questions

Solar energy is the key to a successful transition towards renewable energy, having the potential to address a wide range of the Sustainable Development Goals outlined by the UN. Electricity harvested through the power of the Sun contributes to responsible production patterns in the form of sustainable infrastructure which can provide affordable and clean energy, contributing to the sustainability of human settlements and thereby also to the mitigation of climate change.

In light of the identified importance of solar energy in the transition towards renewable energies, we seek to investigate the temporal and spatial development of the exhaustion of the photovoltaic potential of Switzerland’s roofs and facades by comparing the power of currently installed photovoltaic plants to the theoretical potential determined for each municipality by the Swiss Federal Office of Energy. Moreover, we also aim to examine possible correlations with socioeconomic factors that might hinder or boost the development of solar energy adoption in Switzerland. Therefore, we plan to investigate the following research questions and hypotheses with the ultimate goal of informing policies to promote greater access to renewable energy.


The map frame consists of four elements: the main map, two plots depicting the development of solar energy potential exhaustion since 2005 and the relationship between the socioeconomic variables and the exhaustion respectively and a control panel, which can be used to alter the information displayed in the two plots. The radio buttons labeled “Political orientation” and “Home ownership” may be used to switch between the views of the two socioeconomic variables in the bottom right plot.

The map shows the exhaustion of photovoltaic potential for every canton of Switzerland. A canton may be clicked to reveal the municipalities within the canton including their exhaustion. The municipalities can once again be selected, which adds them to the plots on the right and allows for the comparison of the development of the exhaustion over time as well as of the relationship between the exhaustion and political orientation or homeownership rate between different municipalities. For additional comparisons, the exhaustion of cantons and municipality types over time may be added to the plots via the boxes in the control panel. Selecting a canton or municipality type also causes the municipalities they contain to be highlighted in the plot depicting the relationship between the socioeconomic variables and the exhaustion of the photovoltaic potential. Elements may be removed from the plot through the button labeled “clear selection”.



As of the year 2010, Switzerland is experiencing a massive boom in solar energy adoption which manifests itself in a steady but drastic increase in the exhaustion of solar energy potential. The starting point of this boom coincides for all cantons. In 2019, the exhaustion even surpassed Switzerland’s target of solar energy adoption defined in the energy perspectives 2050+. However, the extent of the increase differs in space. The exhaustion of solar energy potential tends to be higher for smaller cantons, with the highest exhaustion being achieved in the canton of Appenzell Innerrhoden. The cantons with the lowest level of exhaustion are characterized by mountainous terrain, such as Valais, Graubünden and Uri, which is also reflected at the municipality level. Additionally, the exhaustion seems to be comparably low in the big centers such as Zurich, Geneva or Bern as well as in municipalities with hardly any inhabitants. However, a few small municipalities with small potential that contain large plants on industrial buildings display extremely high exhaustion, such as in Onnens off the coast of Lake Neuchâtel in the canton of Vaud. In general, the exhaustion also tends to be high in agricultural communes and secondary centers.

There does not seem to be any clear pattern regarding the correlation between political orientation and the exhaustion of solar energy potential, neither for any of the cantons nor for all of Switzerland. However, the outlying municipalities with more than 10% exhaustion tend to be mainly left-leaning. For the homeownership rate, there seems to be a slight pattern indicating that a higher homeownership rate correlates with a higher exhaustion of photovoltaic potential to some degree. However, this pattern seems to be more pronounced for some cantons than for others.

Solar Energy Cost

The solar energy adoption boom during the 2010s can be mainly attributed to falling costs, as solar energy has become up to five times cheaper over the course of the last decade, leading to more widespread adoption (see graph by Naam, 2020). The fact that smaller cantons tend to display higher exhaustion is likely due to the fact that they have smaller total areas of roofs and facades, which means that the same installation rate leads to a proportionally higher exhaustion of solar energy potential. The reason for the low exhaustion rate of the mountainous cantons of Graubünden, Uri and Valais are not apparent. However, a high exhaustion rate in mountainous regions is paramount for addressing the lower yield of solar power plants during winter, as photovoltaic panels installed on the facades of buildings in regions with a high abundance of snow coverage are particularly effective, due to the high albedo of snow. In general, the adoption rate of solar energy may depend on many factors such as local remunerations or financial support programs for the installation of plants or the return tariff, which refers to the monetary incentive provided by energy supply companies for the feed-in of excess electricity produced by photovoltaic plants into the grid. To the best of our knowledge, there are currently no structured datasets which track these factors at a national level.

We hypothesized that one possible reason for the low exhaustion in large cities is the homeownership rate, which tends to be significantly lower in big centers. The decision of installing a photovoltaic plant is then up to the landlord, who may be unwilling to make the investment or may be discouraged due to maintenance efforts compared to the tenants. However, there does not seem to be a clear correlation between homeownership rate and the exhaustion at a national level. The second investigated factor relates to political orientation, as it may be the case that left-leaning municipalities or cantons tend to be more open-minded towards renewable energies. Similarly to the homeownership rate, we were unable to confirm this pattern. As a matter of fact, some of the right-leaning cantons such as Appenzell Inner- and Ausserrhoden or Obwalden and Nidwalden display higher exhaustions than most of the left-leaning cantons.


The study conducted by the Swiss Federal Office of Energy only accounts for the potential of the areas of roof and facade surfaces but does not consider the potential of freestanding plants, which are significant, as they tend to display much higher power than plants installed on buildings. Therefore, the theoretical solar energy potential tends to be underestimated, which in turn results in an overestimation of the exhausted solar energy potential. Since the dataset provided by the BFS only contains information regarding photovoltaic plants which are used for electricity production, our study neglects solar energy plants which are used for heat production purposes. Such plants will in reality undoubtedly account for a significant proportion of the total solar energy potential. Additionally, we were only able to acquire data regarding homeownership rate for select cities. Values for missing municipalities were imputed using the homeownership rate of their respective district, which means that the results of the homeownership rate analysis might not be entirely representative. Furthermore, we were unable to address the issue that adding to many elements to the plots on the right causes the legend to become cut off, which makes the plots difficult to interpret as many items are added.


Switzerland has experienced a solar energy boom in the 2010s which is bound to continue into the future. The adoption of solar energy varies in space and tends be significantly lower in cantons and municipalities, which are characterized by mountainous terrain. A higher fraction of solar energy potential exhaustion in these places is vital to tackle the temporal fluctuations in yield which are associated with solar energy. There is no significant correlation between the political orientation and homeownership rate of the municipalities and cantons with the exhaustion of solar energy potential in Switzerland. Therefore, these two variables do not seem to constitute barriers to solar energy adoption across Switzerland. Future research should set out to investigate the relationship between solar energy potential and Swiss energy policy measures such as financial support programs to obtain a more comprehensive picture of obstacles for solar energy adoption across Switzerland.

Data & Methods

Map Electricity production plants (BFE 2022): Contains the location, power in kW and commissioning date of photovoltaic plants in Switzerland, which are registered in the Swiss proof of origin system and includes all plants with an output exceeding 30 kilovolt-amperes (kVA), as well as small plants (more than 2 kilowatts) that have been voluntarily registered to display proof of origin. The dataset also includes plants that are subsidized by a feed-in rate, a one-off payment, additional cost financing or an investment contribution. Link
Map Solar energy potential (BFE 2018): Contains the results of the study conducted by the Swiss Federal Office of Energy. The dataset shows the solar energy potential of the roofs and facades for every municipality in Switzerland in GWh for various scenarios with differing assumptions. We work with the scenario that assumes that all roofs and facades will be exclusively used for electricity production and not for heat production purposes. Link
Map Strength of political parties in municipal national council elections in 2019 (BFS 2019): Contains the results of national council elections for each municipality in Switzerland in terms of the fraction of obtained votes for each party. Red depicts more conservative, blue more liberal areas. Link
Map Homeownership rate (BFS 2021): Contains the homeownership rate for select cities Link, districts Link and cantons Link. The darker the color, the more homes are owned rather than rented.
Map SwissBOUNDARIES3D (swisstopo 2023): Contains the geometries of the municipalities and cantons provided by the federal office of topography, swisstopo. It serves as base geometry for the map used. Link
Map Typology of municipalities (ARE 2014): Contains the classification of municipalities in nine distinct typologies. Namely, big centers, secondary centers of big centers, crown big centers, medium centers, crown medium centers, small centers, peri-urban rural communes, agricultural communes, and tourist communes. Link

The fraction of exhaustion of photovoltaic potential for a municipality or canton is determined by computing the sum of the installed power of all plants within the respective municipality and converting the power to an energy output by assuming a factor of 950 kWh per kWp, which according to Baumgartner et al. (2015) corresponds to the standard yield of PV plants in Switzerland. The computed energy output was subsequently divided by the photovoltaic potential determined for each municipality by the Swiss Federal Office of Energy to obtain the fraction of exhausted solar energy potential.

The political orientation is determined by assigning a score to every Swiss political party based on whether they tend to be left- or right-wing. The orientation of a municipality is then computed as the weighted average between this score and the fraction of votes that the party managed to obtain in the respective municipality or canton. This yields a numerical score which indicates whether a municipality tends towards the left or right.

After calculating the relevant statistics on the municipality-level, the values were subsequently aggregated to the canton and municipality type-level, which helps us to tackle the modifiable areal unit problem during this study. Obtaining the installed power and the solar energy potential at a higher aggregation level involves a simple sum of the values associated with the municipalities within the respective canton or municipality type. A weighted sum with the population of a municipality is required to aggregate the political orientation, otherwise small municipalities would have a disproportionate influence.

GitHub The full data processing workflow as well as the script used for generating the visualizations can be found on our Github



This website was developed at the Department of Geography of the University of Zurich as part of the class “GEO 454 Geovisualization“ over the course of Spring Semester 2023. If you have any further questions, please hesitate to contact us!

Joris Senn

Coding & Implementation

Simeon Lüthi

Coding & Design

Jon Guler

Website & Research