Land typically is designated either to generate electricity via solar photovoltaics or to grow crops — but not both.
However, an agrophotovoltaics (APV) pilot project near Lake Constance in Germany shows that both uses can be compatible.
In the demonstration project Agrophotovoltaic – Resource Efficient Land Use (APV-Resola), led by the Fraunhofer Institute for Solar Energy Systems ISE, solar modules were installed directly above crops.
“The agrophotovoltaic system proved suitable for the practice and costs as much as a small solar roof system. The crop production is sufficiently high and can be profitably sold on the market,” said Stephan Schindele, project manager of agrophotovoltaics at Fraunhofer ISE.
(Read "How Does Solar Energy Work? PV Basics.")
Winter wheat, potatoes, celeriac and clover grass were the first crops to be tested. The southwest orientation and the extra distance between the five-meter-high rows of bifacial glass PV modules helped expose the crops to uniform solar radiation.
The crop yield of clover grass under the PV array was 5.3 percent less than the reference plot. The yield losses for potatoes, wheat and celeriac were between 18 to 19 percent.
The 720 bifacial solar modules produce solar electricity not only on the front side but also on the back side with reflected solar radiation. Under favorable conditions, for example snow cover, 25 percent additional electricity yield can be achieved.
The PV array had an installed capacity of 194 kilowatts. In the first 12 months, the array produced 1266 kilowatt-hours of electricity per installed kilowatt, one third more than the average value of 950 Wh/kW in Germany.
Power production from the experimental field matched well to the daily farm load. About 40 percent of the electricity produced on the farm was used directly to charge electric vehicles and process harvested crops. In summer, the load demand could be almost completely met by the photovoltaic system, the researchers say.
The research project is supported by funds from the German Federal Ministry of Education and Research (BMBF) and the Research for Sustainable Development (FONA).