At Agri solar parks, actual farming takes place on the very same land that is used by the solar panels. What technical aspects are involved in this dual approach? Technical specialist Kees Heijmerink of Sunvest explains:
Utrecht, February 2024, Kees Heijmerink, technical specialist Sunvest. fotocredits: Voorbeeldfotografie
We have been developing agricultural solar parks for some time now in France. At these parks, we combine crop cultivation or livestock rearing with solar power generation. We expect to be introducing this concept in the Netherlands soon. The combination of solar power generation and agricultural work requires the technical system to meet different requirements than if the solar panels merely sit amidst nature.
Growth of surrounding crops
One important aspect of the solar panel system is that it is designed to minimize its effect on the growth of surrounding crops. This means that sufficient sunlight has to be able to reach the soil all across the farmland, to ensure that the herb-rich grass can grow freely. There are several ways to deal with this challenge.
Agri Solar farms
First of all, our Agri Solar farms have a much lower panel density than traditional solar parks. The percentage of surface area covered by solar panels is 30 to 40 per cent, instead of the typical 75 to 80 per cent. In Germany and France, legislation and standards have already been passed that provide guidelines regarding surface area coverage. Whilst the prospected crop growth is lower than in a similar plot of land that contains no solar panels, choosing the right crops and caring for them appropriately enables us to still achieve a yield of at least 80%.
Vertically positioned solar panels
We also design solar parks with vertically positioned solar panels that absorb sunlight on both sides. We space these panels out far enough (7, 10 or 13 metres) so that farmers can still manoeuvre their tractors between the rows using GPS to sow or mow the land. We position the rows of solar panels from north to south, so that the movement of the sun across the sky provides even light distribution across the soil.
Single-axis trackers
The third type of system we use in our designs is more expensive, but also results in considerably higher yields: single-axis trackers. In this case, the solar panels are mounted to a single long, rotating axis. The panels and the axis are positioned from north to south, and the panels gradually angle from the east to the west; in short, the panels track the sun’s path as much as possible. Just like the other options, this system provides excellent light distribution across the soil and grassland during the day. The single-axis system also allows for excellent rain water management; for example, the panels can be tilted even further in the event of rainy, overcast weather to ensure that the soil is watered evenly. Another advantage is a better distribution of the power generated throughout the day compared to a standard south-facing set-up, with less of a peak in generated power around noon.
The height of the solarpanel platforms
A next important aspect of Agri Solar’s solar panels is that animals need to be able to pass underneath the panels and/or farmers need to be able to fit their tractors and other agricultural machinery between the rows. Our solar panels enable farmers to still mow or perform other agricultural work, even underneath the solar panel platforms. The distances between the panels, or the poles on which they are mounted, are configured depending on the width of the farmer’s equipment. Usually, agricultural machinery is 6, 9 or 12 metres wide. The height of the panel platforms is designed to allow cows or sheep to pass underneath without damaging anything or hurting themselves. For cows, this means a panel height of around 2 metres, and for sheep, a height of around 1.20 metres. If the pasture is used for cows, we also take into account the fact that the poles need to be stronger. On a sunny day, the animals can enjoy the additional shade these solar panels provide! Our single-axis tracker systems enable farmers to temporarily position the panels upright whenever they wish to work the land unobstructed.
Agri Solar is truly a win-win situation
Agri Solar is truly a win-win situation, providing a higher combined agricultural and solar power yield than farmland that is used solely for agricultural purposes or solely as a solar park, namely up to 160%. Additionally, Sunvest enhances the ecological value/biodiversity in its solar farms. Using the right technical aspects, we make sure that our nature-friendly Agri Solar panels provide added value for both the agricultural community and the natural environment.
