Solar Profiles and Spectral Modeling for CPV Simulations

In this paper, a computer model for the simulation of solar flux distribution in the direct and circumsolar regions of the beam irradiation is presented. The model incorporates circumsolar ratios (CSRs) and spectral transmittance. It is used to demonstrate the importance of realistic solar flux distributions as source inputs in high-concentration concentrator photovoltaic simulations. Realistic solar flux distributions are achieved by treating the Sun as an inhomogeneous extended light source. Flux distributions incident on lenses of various entry apertures are generated and used to investigate the losses in incident flux resulting from tracking errors and CSR variation. It is found that, for a Seattle-based concentrating system with an entry aperture of 0.5°, a ~5% loss in net annual incident flux occurs with a uniaxial tracking error of 0.3°, and a ~20% loss occurs with a uniaxial tracking error of 0.4°. This analysis is at the primary concentrator stage; hence, it only considers the flux incident on the surface of the initial concentrating lens. The summation of flux at this primary stage does not account for further losses at the receiver because of optical misalignment.