Effect of misalignment on the performance of a compound parabolic concentrator

Abstract

The recent push for cost reductions in solar electricity production deployment has renewed interest in concentrating photovoltaic systems. One strategy in low-concentration systems has been to reduce balance-of-system costs by reducing tracking accuracy requirements and/or eliminating tracking in the azimuth or altitude direction. However, misalignment with the sun, due to a lower-performing tracker or intentional design, hurts the concentrator's performance. The effect of misalignment on the performance of a 8.1x compound parabolic concentrator developed for inclined single-axis tracking is evaluated. Both the ray tracing simulations and measured compound parabolic concentrator results show significant effects from misalignment on the concentrator's performance. Average irradiance decreases significantly as the acceptance angle is approached in the east-west or north-south direction. Additionally, the maximum irradiance value can increase significantly during misalignment and move locations within the exit aperture, having a significant impact on thermal management design. It is important to incorporate these "real world" effects of intentional and unintentional error in sun-tracking, so that the product design is effective and the true cost of less accurate trackers is understood.