Translating Outdoor CPV I-V Measurements to a CSTC Power Rating and the Associated Uncertainty

A procedure is presented for translating outdoor concentrator photovoltaic I-V measurements to indoor conditions. Unique methods are investigated using outdoor thermal transient measurements and indoor dark I-V curves. Four modules are subjected to the translation method and compared with concentrator photovoltaic simulator measurements. The results show that translated efficiencies of Concentrator Standard Test Conditions are in good agreement with the efficiencies from the solar simulator.

A complete procedure is presented for translating outdoor concentrator photovoltaic (CPV) I-V measurements to the Concentrator Standard Test Conditions (CTSC) (1000 W/m² and 25 °C cell temperature). Methods are demonstrated for measuring all the necessary input parameters for the translation, including outdoor thermal transient measurements and indoor dark I-V curves. Four modules are subjected to the translation method based on multiple months of outdoor data, one module measured at National Renewable Energy Laboratory and three at Fraunhofer ISE. The modules are also characterized under a sun simulator to provide a comparison to the translation approach. The results show that translated CSTC efficiencies are in good agreement with the efficiencies from the solar simulator. Two of the modules agreed within 1%, whereas the other two modules agree within approximately 4%. An uncertainty analysis of the input parameters is discussed in the context of the total uncertainty associated with the translation to CSTC. The reference voltage and efficiency temperature coefficient are the key parameters impacting the translation uncertainty, whereas uncertainty in the outdoor data is driven by spectral and meteorological parameters.