Energy and optical analysis of photovoltaic thermal integrated with rotary linear curved Fresnel lens inside a Chinese solar greenhouse

In this paper, a cylindrical Fresnel lens concentrating photovoltaic/thermal (CPV/T) system is established in the non-planting area of the Chinese solar greenhouse. The system changes as the solar elevation angle changes between the summer solstice and the winter solstice, ensuring that the light is incident perpendicular to the lens. A row of Fresnel lens at this location does not block the photosynthetically active radiation of the plants in the planting area, and only reduces part of the direct light from the north wall of the greenhouse. The space utilization rate of non-planting space is 18.2%. Through optical simulation, the acceptance rate has little effect when the axial incident angle is within 10°. In contrast, the concentrating performance of the cylindrical Fresnel lens is better than that of the elliptical and parabolic Fresnel lenses. In actual weather, an experimental study was conducted on a concentrating photovoltaic/thermal system in which a gallium arsenide concentrating cell was used as a receiver. The main parameters such as temperature distribution of the concentrating photovoltaic/photothermal system receiver, output power and thermal power, utilization efficiency of electric energy and thermal energy were tested. The test results under clear sky conditions show that the maximum power generation efficiency is about 18% at noon (11:00–13:00), the maximum thermal efficiency of cooling water is about 45%, and the total efficiency of thermal and electrical power is about 55%. Combined with facility agricultural engineering, it comprehensively solves the problem of land resource utilization and comprehensive utilization efficiency of solar energy system.