A novel integration of supplementary photovoltaic module into compound parabolic concentrator for accelerated defrosting of solar collecting system

In order to improve the temperature of solar greenhouse in winter and reduce the cost and energy consumption of traditional heating methods for solar greenhouse. This study presents a novel compound parabolic concentrator (CPC) coupled with a supplementary photovoltaic (SPV) module for soil heating in solar greenhouse. Firstly, a novel SPV-CPC was designed and its optical model was established by TracePro. The optical and thermal performance of the novel SPV-CPC and the traditional CPC under the same conditions were compared. The results indicate that the SPV module can intercept and utilize the escaping rays when the incident angle is large, for example, at the incident angle of 15°, the light receiving ratio of the novel SPV-CPC and traditional CPC are 78.50 % and 61.50 % respectively. In particular, the SPV module can effectively capture rays in early morning of winter to accelerate the defrosting on the glass cover. Under sunny days, the solar heat collection performance of the SPV-CPC is similar to that of the traditional CPC, and their photothermal conversion efficiencies are 54.61 % and 54.05 %, respectively. However, owing to the SPV module, the overall primary-energy saving efficiency of the SPV-CPC is 64.09 %.