Is there just one form of agrivoltaics?
No, there is not just one single form. Different systems are being trialed in Germany and elsewhere in Europe depending on the application. There are large panels on tall frames that combine harvesters and other agricultural machines can drive underneath, for example in fields where wheat or sugar beet is being grown on a large scale. Then there are the systems for specialized crops, such as raspberries, blueberries, apples, or vegetables, which are much lower and have different types of solar modules. In addition, there is the option of positioning the solar panels vertically, so that crops can be grown between them. This is ideal for grassland or hay production. And it is important to remember that photovoltaic systems can be integrated into glasshouses. Research is currently ongoing in this area, for example at the Forschungszentrum Jülich we are experimenting with organic PV modules that are partially translucent.
In the case of the specialized crops that you mentioned, the plants are covered by the solar modules. How are they watered?
Rainwater is collected from the panels and supplied to the plants by an irrigation systems. The pumps use a very small proportion of the electricity that is generated. The other advantage of irrigation systems is that they provide plants with water exactly where and when they need it.
Are all crops suitable for agrivoltaics?
Plants that need a lot of light, such as sunflowers, are less suited to agrivoltaics. By contrast, for crops that thrive in semi-shade, such as blueberries, the system works well. Projects are currently underway to investigate leaving larger distances between the panels for plants with a greater need for light. However, this means fewer modules in a given area and less electricity being generated. But we must not lose sight of the cost structure. To ensure that the system is cost-effective and therefore scalable, it is, of course, important to use standard modules that are low in cost, reliable, and easy to obtain.
Agrivoltaics generates renewable electricity and reduces land use. How important is another aspect of these systems: plant protection?
In my view, that is one of the main arguments in favor of agrivoltaics. At the research center, we hear from farmers who are losing 90 percent of their harvest because of extreme weather. This type of event will become more common as a result of climate change. More and more specialized crops are being protected with hail nets that have to be replaced every few years. Solar modules provide longer-lasting protection, including against too much rainfall, sunshine, and dry weather. Tomatoes and raspberries, for example, do not like wet conditions. In this case, a protective agrivoltaic system can even increase yields and prevent crop failure.
To run an agrivoltaic system cost-effectively, farmers need to acquire a lot of expertise…
Not necessarily. There are business models where the systems are installed and operated by photovoltaic companies that look after the technical issues. But many farmers want to learn about agrivoltaics and are keen to take on the challenge. Some of them are planning, for example, to incorporate areas of specialized crops or vegetables with agrivoltaics into their wheat or sugar beet fields, but it is not possible to do that overnight. In addition, they will need to set up new sales channels and supply chains.
What is your view of the regulations in this respect?
We very much welcome the fact that the coalition government wants to subsidize agrivoltaics. But the decisive consideration is that farmers continue to receive money from the EU agricultural subsidy schemes alongside the government funding, because under current law a solar farm no longer counts as agricultural land and therefore is not eligible for EU subsidies. All the agrivoltaic systems that are in operation require special approval. This means that to promote agrivoltaics, planning law needs to be changed. We are very interested to see what the package of legislation that is being introduced in the next few months will contain.