A photovoltaic (PV) module testing system was installed at latitude 42.6978 and longitude -83.2419 in 2010 for the purpose of evaluating the impacts of irradiance, temperature and angle-of-incidence effects on PV performance. The system consists of a source-meter coupled with a data acquisition system that collects readings from weatherstation instruments tracking irradiance, temperature and wind speed. Current, voltage and power observations, correlated to our weather-station device readings, were collected from c-Si, a-Si and CIGS PV modules. We observed thermal annealing in a-Si and the effects of temperature on c-Si and CIGS. c-Si module temperatures above 25°C appear to diminish power by approximately 0.5%/°C. Our results also support the hypothesis that a-Si modules deliver more energy (kWhrs) per peak-watt (W_p) than other PV materials. This is important because PV is typically sold on a $/W_p basis. The W_p rating is based on a module's performance under standard test conditions of 1000W/m~2, 1.5 air mass (AM) and 25°C module temperature. A PV rating system proposed by the International Electrotechnical Commission (IEC) creates a series of testing conditions based on a variety of weather conditions. The system is capable of collecting observations fitting most of these test conditions [1].
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