Design and Analysis of a CPV Retrofit for Parabolic Trough Powerplants

Concentrating photovoltaic (CPV) systems represent a well-established means to utilize high-efficiency multi-junction cells coupled to lower cost concentration systems to achieve low levelized cost of electricity. While specialized point-focus concentrating optics are commonly deployed for high CPV systems, significant cost reduction is possible if an existing primary optics platform could be exploited. Here, a secondary optical feature is developed that utilizes the existing primary optics of a parabolic trough type solar thermal powerplant and enhances its power output. A cost-optimized design with CPV receivers replacing the existing heat collection elements is analyzed with a concentration ratio of 94 suns and a designed focal width of 18 mm extending linearly along the trough axis. A heat transfer model is developed to predict cell performance using empirical relationships for efficiency for a SolAero multi-junction CPV cell. The results are then utilized to calculate a simple levelized cost of electricity for the proposed retrofit system. The secondary optics platform has been constructed with a small number of cells to evaluate performance and was installed on-sun at The University of Tulsa. On-sun efficiencies were measured at a peak of 13.5% while operating at 70-90 suns and 90 °C. The retrofit shows a pathway to potential LCOE of less than 0.06/kWh by leveraging existing primary optics.