New design of installations for agrivoltaic – pv magazine International

Developed by Chinese researchers, the new design methodology involves using metal brackets as mounting structures, conventional solar panels, and a grooved glass plate placed between the solar panels. According to its creators, it ensures an increase in the average income of a farmer by 5.14 times, including the solar energy production activity. A system built with this approach should cost around €715 per kW installed.

A group of researchers from the University of Science and Technology of China has developed a special design for agrivoltaic projects which, compared to other approaches, claims to reduce the shading effect of the photovoltaic installation and improve the crop light environment and crop growth process, yield and quality.

“The system has a cost 10% higher than a classic agrivoltaic project, but the improvement in crop yield provided by the optimized lighting management would compensate for this slightly higher investment”, said the co-author of the research, Jan Ingenhoff. photo magazine.

In terms of economic feasibility, a system developed with the proposed approach should be built at a cost of around €715 per kW installed and an annual maintenance cost of around €6.5 per kW.

Glass

Called the Even-lighting Agrivoltaic System (EAS), the new design methodology uses metal brackets as mounting structures, conventional solar panels, and a grooved glass plate placed between the solar panels. The latter occupies an area corresponding to one-third of the light-receiving area of ​​the entire system. “With the installation of the glass plate, the density of the photovoltaic panels is the same as that of conventional photovoltaic power plants and very close to the optimal design for energy production,” the scientists asserted.

According to Ingenhoff, any ordinary high-transmittance glass can be used, as there are no special requirements, and silicate glass and ultra-white glass can be fine.

The metal supports are placed on columns high enough to allow the growth of tall plants and the use of large agricultural machinery. The optimal tilt angle for the modules was determined at 23 degrees, which the research group described as a good compromise between power generation and construction costs.

Demonstrators

Scientists first calculated and optically simulated the design of the grooved glass plate, then built a first pilot 35 kW agrivoltaic project in the city of Fuyang, in the Chinese province of Anhui. Common vegetables like lettuce, broccoli, garlic sprouts, garlic, rapeseed, Jerusalem artichoke, among others, were then planted.

A second pilot system was deployed more recently in the city of Hefei, in the same Chinese province.

The pilot project in Fuyang City, Anhui Province.

Image: University of Science and Technology of China

The EAS system has improved growing conditions for some plants. For example, the Jerusalem artichoke harvest increased by more than 20%. The reason behind this may be due to better soil moisture retained in the area of ​​the plant, or the fact that the plant can remain under photosynthesis between 11:00 p.m. and 2:00 p.m. on days with good solar radiation, which usually enters a dormant state. for the plant. outdoors, as leaf photosynthesis peaks in the late morning.

For both installations, the height at which the solar panels were placed was 2.5 meters. Some of the plants also grew under the system fitted with additional LED lights powered by the solar panels, which provided the plants with an additional 2 hours of light time per day compared to the other treatments.

Yield

“The overall economic benefits of EAS include installation and maintenance costs, power generation benefits, and crop harvesting benefits,” the scholars explained. “To accurately assess the overall benefits of planting different crops, we considered the time needed to plant different crops and the amount of electricity generated by the photovoltaic panels during crop growth.”

According to their measurements, the use of the transparent grooved glass plate improved the irradiation captured by the crops in one day by 47.38% compared to a conventional system, and the yield of Jerusalem artichoke, which needs at least six hours of sunlight per day, improved by 23%.

The protester in Hefei City.

Image: University of Science and Technology of China

Including solar power generation, the system showed that the average income of a farmer increases by 5.14 times and achieved a high land equivalent ratio (LER), which is the measure of productivity and efficiency. effectiveness of intercropping. It also improved the economic benefits on agricultural land per hectare.

“Under the EAS, the crops grew rapidly and the yield was similar to or better than that in the natural state,” the Chinese group noted. “By adding additional LED lights in the EAS, the soluble sugar content of lettuce increased by 72.14% and the nitrate content of lettuce decreased by 21.51%.”

More details on the system design can be found in the document Increasing the overall economic benefits of farmland with uniformly lit agrivoltaic systems, Posted in Plos One.

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Leon E. Hill