The microclimate under the panels can be good for the plants — cooler in the summer and warmer in the winter — with a positive effect on the harvest. The panels also protect the crops from rain and hailstones, which reduces the risk of fungal rot and hail damage. Nature-inclusive solar farms are another example of multifunctional land use. Stremke: “You can use them to enhance biodiversity, for example. If you take a field in an area with intensive arable farming out for production for 25 years, that gives the soil a chance to recover because you aren’t removing organic mass or adding fertilizer.” Surrounding the solar farm with hedges and verges full of flowers also increases biodiversity. What is more, that makes the solar farm less visible, which can reduce local people’s resistance to the farm.

Municipalities and landowners need to think hard about their choices when constructing solar farms, says Stremke. The One Wageningen Solar Research Programme, of which he was one of the initiators, can help them with this. The programme aims to provide a scientific basis for developing sustainable solar farms that benefit the economy, nature and society at large. “There are lots of decisions to be made when building a solar farm: do you just want to generate energy or also contribute to agriculture and biodiversity? Do you want to do something for local residents, for example by combining the solar farm with recreational or educational facilities? In this programme, in which we collaborate with public authorities, landowners and energy suppliers, we see that such decisions are often made right at the start of the project and they are also often implicit. The landowner and developer approach the municipality with their design, and local residents only see it much later when they can’t really have a say anymore. Whereas getting residents involved earlier is an effective way of preventing resistance.”

In addition to giving people a say, participation is a key method for generating public backing for a new solar farm. Stremke: “If you can invest personally in the solar farm as a local resident, rather than some unknown investor company, you feel much more engaged with the project.” A town can also welcome this opportunity to help the energy transition if the solar farm simultaneously offers a solution for long-standing local problems — a rubbish dump, an area where the soil is exhausted due to intensive agriculture, or a plot designated for a business park that was never built.

According to Stremke, WUR has an important role in keeping policymakers alert. “We can show policymakers that a particular option they have in mind didn’t work out well in other countries, for example. Or we can tell them what does work well. In Germany, the grant system for renewable energy is updated annually to take account of new scientific insights. For example, at one point there were concerns about competition between agriculture and energy generation. So the German government reduced the grant for solar panels on farmland and raised it for solar panels on poor-quality, inaccessible land, making it more attractive for developers to build their solar farms there.”

Fortunately, the Netherlands is also starting to change its approach to grants for sustainable energy, says Stremke. At first, the focus was exclusively on the cheapest option — and putting up solar panels in an empty field happens to be cheap and easy. But now that we are running out of such plots for low-cost, large-scale solar farms, Stremke argues that fitting the solar farms into the landscape is the only way to achieve the required energy transition. The new Dutch government seems to realize this: the coalition agreement mentions multifunctional solar farms.

While the research has resulted in a much better understanding of specific aspects such as land use and visibility, more studies are needed, for example on maintenance and circularity in material use. Stremke wants to combine this research with actual practice. “We’re currently carrying out several ‘action-research’ projects in which we develop the solar farms of the future. That will let us focus more on a third aspect of our research, namely the temporary nature of these farms and, consequently, circularity. If a solar farm is taken down after 20 years, the land can be reused for other purposes. So it is important to make sure everything is degradable or can be recycled where possible.”