Researchers combine agrivoltaics with insect net house

A research team from India has developed an agrivoltaic insect net house (AVINH) that combines solar power generation with protected cultivation of peppers.

The team constructed two types of AVINH structures, then conducted microclimate, statistical, and economic analyses, as well as a land equivalent ratio (LER) determination.

“AVINH offers several environmental advantages, including lowering carbon emissions, reducing the need for pesticides, and decreasing soil erosion and evaporation while providing farmers with a guaranteed income,” the research team said. “To assess this technology under practical circumstances, the study was carried out at a research farm.”

The research farm is located in the Indian state of Gujarat. The two AVINHs both incorporated 12 solar panels rated at 150 W, with one AVINH featuring an open roof and the other a closed roof.

The covered-roof AVINH had insect-net material stretched across the gaps between the PV modules, while the open-roof AVINH left these gaps uncovered. The rest of the structure was identical, with the net house measuring 8.04 m in length, 4.10 m in width and 3 m in height, with a white insect net made of 40 meshes stretched over it. An additional S3 design of conventional open-field cultivation was used as a control.

Under each structure, three pepper plots were planted, each with a different treatment. The first plot (T1) consisted of raised beds covered with mulch, the second (T2) combined raised beds, mulch and biofertilizers and the third (T3) used a soilless growing medium made of vermicompost and cocopeat together with biofertilizers. In each case, the researchers measured air temperature, relative humidity, light intensity and solar radiation using HOBO data loggers and solar-tracking instruments. Measurements were taken between December and March.

The scientists said that over the course of the experiment, the facility generated 1,058.30 kWh of energy, which they said was more than conventional power plants and standard agrivoltaic systems

“The reason for this higher energy conversion is that plant evapotranspiration cooled the solar panels on the back side,” they explained. “The capacity factor associated with this energy conversion system exhibits a minimum fluctuation, ranging from a minimum value of 19.42% to a maximum of 21.15% throughout the experimental period.”

The team tested the LER, which compares the combined food and electricity output of an agrivoltaic system to that of separate crop and solar production, with values above 1 indicating more efficient land use. The highest LER was achieved under the covered AVINH with T2, with a score of 2.55. T3 under the covered AVINH came second, with 2.28, while T1 under the covered AVINH achieved 2.26. Under open-roof conditions, T1, T2, and T3 had LERs of 1.82, 1.68, and 1.67 respectively.

“The system’s reasonable payback period of eight years underscores its economic viability,” the group had concluded. “To further optimize and expand the application of AVINH systems, future research should focus on identifying ideal shade-tolerant and shade-resilient crop varieties. Investigations into diverse AVINH designs and materials are crucial for fine-tuning microclimate conditions to enhance crop growth.”

The team’s results appear in the research paper Agricultural intensification with Agrivoltaic insect net house systems: Delving into techno-economic feasibility in soilless media, published in Energy Nexus.

Scientists from India’s Vellore Institute of Technology and Junagadh Agricultural University participated in the research.