Performance analysis of a low concentrating PV-CPC system

Concentrating solar photovoltaic (PV) cells seems to be the most viable method to reduce the cost of the direct conversion of solar radiation to electricity. A non-imaging concentrator, namely Compound Parabolic Concentrator (CPC) with a flat receiver is considered in this research to compose concentrating photovoltaic cells. CPC requires intermittent tracking and has large acceptance angle to receive both beam and diffuse solar radiation. In this paper modeling of the truncated CPC with a concentration ratio of about 2.3 is carried out for concentrating PV strings by solving the governing equations using Engineering Equation Solver (EES) software. Reflection losses occurring at each interface are considered in the model and determined by the angle of incidence of incident radiation and by the refractive indices of the materials at each interface. Absorbed energy is calculated for different cases, with and without cooling, including PV-CPC (glazed and un-glazed) and simple flat P V. This absorbed energy is further used to solve the energy balance equations on different nodes of the system. By solving the energy balance equations iteratively, the cell temperature is estimated. Cell temperature and the absorbed radiation are used as input to electrical model. Electrical model is simulated and performance characteristics curve for the PV-CPC systems are obtained. The performance of the PV string with and without cooling for all the cases is compared in this paper. Results show that electrical power is enhanced up to 49.4% by integrating PV (actively cooled) with un-glazed CPC. This indicates that PV-CPC is an efficient way to reduce the cost of electricity produced by P V.