Agri-photovoltaics: Solar power from the field – double harvest
How it works
Agriculture food production requires a great deal of land surface. Large photovoltaic installations also take up lots of space. Increasing the number of plants is urgent if the climate goal is to be achieved. It would reduce dependency on fossil resources and increase Switzerland’s security of supply in the future. Agriphotovoltaics (Agri-PV) could offset the escalating competition for land between agriculture and energy supply and create a win-win situation for both sides.
This still new concept is as simple as it is elegant: While corn, potatoes or fruit and vegetables are harvested on the ground, electricity is generated overhead. In the best case, fields and pastures produce more than before because the photovoltaic modules protect the land from hail, frost and droughts. Potatoes, leaf vegetables, field forage (grass/clover mix), various types of stone fruit, berries and other special crops (wild garlic, asparagus and hops) are well-suited for this type of production.
According to the Food and Agriculture Organization of the United Nations (FAO), Agri-PV plants belong to the integrated food-energy systems (IFES) and can be grouped broadly into open and closed systems. The latter primarily refers to greenhouse roofs covered with PV modules. Through its subsidiary Urbasolar in France, Axpo has wide experience with these types of solar plants.
There are two types of open systems: Elevated plants with PV modules on stilts and systems with PV modules installed close to the ground. In the first case, the modules are installed several metres above the ground enabling the use of the land directly below the panels so that large agricultural machines can pass underneath easily. These elevated installations can create a beneficial micro-climate, cooling plants during the day through a chimney effect, and maintaining a temperature higher than that of the environment during the night. In the second case, crops are typically cultivated between PV module arrays installed close to the ground.
An Agri-PV installation can be realised as a fixed substructure or as a 1- or 2-shaft mobile construction known as a solar tracker. In the course of the day the trackers follow the sun's position and produce a higher electricity yield.
Our Agri-photovoltaics
Photovoltaic systems are an important pillar to enable the coverage of future power demand in Switzerland. Axpo is also massively developing solar energy. In Switzerland, Axpo focusses on large-scale PV plants in the midlands or in the mountains (winter power). Whenever possible, land with existing infrastructure will be used. An example is the pioneer plant AlpinSolar, which was built on the Muttsee dam in the Glarus Alps.
Switzerland is still in the early stages of so-called agriphotovoltaics which does not use existing buildings for installations, but combines them with agricultural land instead. France is one of the leaders for these types of systems in Europe. Through its French subsidiary Urbasolar, Axpo has acquired broad experience with Agri-PV systems. For example, Urbasolar has built over 20 photovoltaic greenhouses, and numerous projects are in the pipeline.
NalpSolar, Canton of Grisons, Switzerland
Axpo plans to build NalpSolar, a ground-mounted plant. It will be erected above the Lai da Nalps reservoir in the Canton of Grisons at some 2000 metres above sea level, and have an installed capacity of 10 megawatts. This entails 30,000 solar modules that will be mounted over alpine pastures on a surface corresponding to some 12 soccer fields. During the summer, the installation over the pasture will produce 13 gigawatt-hours of electricity per year while cows graze underneath in the shade of the modules. This production covers the electricity consumption of about 3000 households.
Mont-Prés-Chambord, France
In the small French town of Mont-Prés-Chambord, southeast of Le Mans, the Axpo subsidiary Urbasolar has built a photovoltaic plant in cooperation with the town in order to utilise unused farmland for agriculture purposes. The plant has been designed so that a local farmer can use the land to graze his sheep. At the same time, the solar panel arrangement makes it possible to use the land as pasture and to produce crops. For example, the distance between the panel arrays was calculated to enable optimised, mechanised crop production. The solar power plant has an installed capacity of 4.4 MW and generates 5,350 MWh of electricity per year. This supplies about 2,500 people with climate-friendly electricity.
Berre l'Etang, France
In France, Axpo subsidiary Urbasolar has already installed solar modules on the roofs of several agricultural greenhouses. One example is the project in Berre l'Etang, where the farmer Stephanie Facon-Retaux and her husband grow strawberries and raspberries on their farm. The berries are sensitive to the weather. Storms, hail and frost can lead to significant crop losses. Greenhouses covered with solar modules, on the other hand, offer protection and thus more yield security. The solar modules on the couple's farm cover an area of 29,162 m2. The installed capacity is 2.8 MWp. Overall, this solar greenhouse leads to a better diversification of distribution channels and ensures a diverse, local, high-quality and environmentally friendly supply.
Regulatory framework
According to the Federal Spatial Planning Act (SPA), solar plants in agricultural zones are basically only allowed on roofs. Ground-mounted plants can only be erected outside the building zone, e.g. in agricultural areas, with an exemption permit and with proof of site-dependency. Up until mid-2022, solar plants that could not be justified through site-dependency were de facto illegal because they could be erected elsewhere.
Since 1 July 2022, the Spatial Planning Act now lists criteria for site-dependent Agri-PV systems. According to Article 32c, solar plants with a connection to the power grid but located outside of building zones can be considered site-dependent if they "benefit agricultural production in less sensitive areas or serve for test and research purposes." The amendment "Benefits for Agricultural Production" restricts Agri-PV to crop plants that require less light and benefit from shade. Under the so-called blanket waiver, the Swiss Parliament plans to anchor the criteria for agriphotovoltaic site-dependency on a legislative level. The discussions are under way, and it remains to be seen what changes are ultimately made (scheduled entry into force as of 2025).
The elimination of direct payments for agricultural land when solar plants are installed represents an additional hurdle for agriphotovoltaics. This is because Agri-PV is currently not concurrent with the prerequisites for agrarian use. A review to adapt these prerequisites should be carried out in order to advance expansion.
Agri-photovoltaics from A to Z
The most important answers on Agri-PV
Agri-photovoltaics or Agri-PV combines agriculture with the generation of solar electricity and, as a result, alleviates the increasing competition for land between the agriculture and energy sectors. Thanks to its great potential it could make a significant contribution to the security of electricity supply. Solar plants could be built on agricultural land in such a way that they would have the least possible impact on agricultural yields. Depending on cultivation and crops, yields could even be increased because the plants are better protected from heat, heavy rains, hail and frost thanks to the solar covering. In fact, Agri-PV can create a double harvest: Solar power and food.
Be it agrophotovoltaics, agrarian photovoltaics, or agri-photovoltaics – various terms are used. They all mean the same thing: the combination of solar energy and agricultural production. Axpo uses the term agriphotovoltaics or Agri-PV.
The Agri-PV idea originates in Germany. It was the founder of the Fraunhofer Institute for Solar Energy Systems ISE, Adolf Götzberger, who first presented the concept to the interested public in the article «Kartoffeln unter dem Kollektor» (Potatoes under the Collector) in 1981.
However, first reactions were reticent. It took about three decades before the concept became of interest – not for solar collectors, but rather for PV modules – in view of the climate crisis and growing energy demand. In the 2000s, the first Agri-PV pilot plants were erected and monitored in Japan and later in Germany and France. Switzerland also supplied data on strawberry and raspberry cultures from the pilot plant of the Federal Research Institute Agroscope, located in Conthey (VS). In German-speaking Switzerland the ZHAW confirmed that lamb’s ear lettuce grew better under solar modules in its own test facility in Wädenswil.
According to the Fraunhofer Institute for Solar Energy Systems ISW there are currently installations around the world with a total capacity of 14 gigawatts. As a comparison: In 2012, installed capacity was only about 5 megawatts.
Japan has been promoting Agri-PV as the first country to do so since 2013. China, France and the USA have followed, and Italy is also a pioneer in the area of Agri-PV. The largest Agri-PV project to date was built in China at the edge of the Gobi Desert and is currently being expanded to a capacity of 1 GW. In contrast, Switzerland is still in the early stages. Axpo intends to make a decisive contribution to the expansion of domestic Agri-PV. With its French subsidiary Urbasolar, the company already has years of experience in the construction of solar plants, including Agri-PV systems.
Switzerland faces a huge challenge: By 2050, we will lack some 50 terawatt-hours of electricity. On the one hand, the nuclear power plants will be successively taken off grid. Over the past years some investments were made in existing hydropower, but expansion is blocked and there is now a decline due to residual water regulations. On the other hand, electricity demand is increasing due to more electro-mobility, the use of heat pumps and other technologies.
As a result, the Swiss Federal Government wants to massively develop photovoltaics. According to the Energy Perspectives 2050+, about 34 terawatt-hours (TWh) will come from photovoltaics by the year 2050. That is about twelve times more than today and represents over 40 per cent of power demand. The required solar installations would cover an area about the size of the Canton of Appenzell. It becomes clear: We will not be able to avoid the construction of large-surface PV plants.
However, if they are built on green fields, they will be met with resistance in tiny Switzerland. Solar plants on agriculture land could have a higher degree of acceptance.
Building roofs and façades offer ample space for PV modules. However, to fully take advantage of this potential in Switzerland, about 95 per cent of buildings would have to have PV systems installed on roofs. This is unrealistic and would take too long.
According to SolarPowerEurope the use of just 1 per cent of agricultural land in combination with Agri-PV systems would result in a capacity of 700 gigawatts.
And in Switzerland? Detailed feasibility studies by ZHAW in 2022 indicate a great deal of potential lies on uncultivated farmland.
A summary of the findings: In Switzerland, slightly more than 1 million hectares are agricultural land, which is about one fourth of the country's land area. The agriculture land is used for pastures and for growing grain, potatoes, wine or strawberries. No one wants to cover these areas with solar panels. That would also not be expedient.
According to the study, Agri-PV systems should focus on agricultural land near residential areas that have enough solar radiation. Areas such as biosphere reserves or protected areas must be excluded from this concept. In addition, the areas that come into question must be close enough to existing power grid feed-in points. These criteria mainly apply to farmland.
After taking other exclusion criteria into consideration, the study comes to a bottom line figure of 256,982 hectares that would be suitable for Agri-PV. Nearly two thirds of this is open farmland. The potential for electricity generation on suitable areas is calculated at 132 terawatt-hours (TWh) per year, which is more than double our power demand today. The report also states that if Switzerland's power demand until 2050 were to increase from today's 60 to 80 terawatt-hours per year, about 10 per cent of this future demand could be covered with Agri-PV, while only 1.1 per cent of agricultural farmland would be needed to do so.
- Dual use of the same land surface: for agriculture and to produce climate-friendly electricity. Instead of competing for land, the agriculture and energy sectors work hand in hand.
- Agri-PV has great potential and could make a vital contribution to the security of electricity supply.
- The solar modules can be installed so that they protect plants from hail, frost or strong rains, or from too much sun, hence, increasing yields. Agri-PV also offers shelter and protection for grazing animals.
- The use of costly and environmentally harmful plastic foil can be avoided. This foil is used in conventional cultivation to protect crops and must be replaced regularly.
- Photovoltaics is generally well-accepted among the population. Agri-PV is likely to come off even a bit better as compared to ground-mounted plants that are installed on open land.
- Farmers can generate additional income with the sale of electricity from renewable solar energy.
- Agri-PV is not suitable for all agricultural land and is restricted to certain crops.
- Depending on the crops and cultivation method, lower yields must be expected.
- The investment costs tend to be higher for Agri-PV as compared to conventional ground-mounted plants.
- Solar modules on stilts are highly visible