Comprehensive optimization of shading and electrical performance of roof-mounted photovoltaic system of Venlo-type greenhouse in the severe cold region

Agrivoltales is a new paradigm that combines agricultural and renewable energy production, which can reduce the energy consumption in severe cold region. Install PV panels on the greenhouse rooftops can provide required power for the greenhouse, but the shading from the PV panels may affect crop development and yield. In this article, the roof-mounted PV system's performances of a novel Venlo-type PV greenhouse in the severe cold region of China were evaluated and analyzed. By controlling the angle between the south-and-north-facing roof and the horizon (alpha and beta) from 10 degrees to 70 degrees, each 10 degrees increase was chosen as a design case, forming 49 cases in total. The shading rate, daily light integral (DLI) and the performance of the PV system were considered to optimize the Venlo-type PV greenhouse. The results show that when alpha is not less than 40 degrees and beta is 10 degrees, the shading rate of Venlo-type greenhouse is less than 25 % and photosynthetically active radiation (PAR) higher than 23.5 mol/m2 & sdot;d which meets the requirements of most greenhouse crops growth. Through comprehensive evaluation, the optimal case is alpha at 40 degrees and beta at 10 degrees, of which the specific production is 1404 kWh/kWp/year which is the most, both investment and energy payback period are the shortest, power generation is 114.9 MWh/ yr, carbon emission reduction is 11202 kg/yr the shading rate is below 25% throughout the year. The case with alpha at 70 degrees and beta at 70 degrees has the largest power generation and carbon emission reduction. However, its shading rate, PAR, specific production, and payback period have the worst performance. The results can facilitate the development of the optimization of PV greenhouses and contribute to the carbon neutrality of facility agriculture and the life of local farmers.