ABSTRACT
Six polycrystalline silicon photovoltaic modules—two apiece from three manufacturers—were simultaneously deployed outdoors on the performance and energy ratings testbed at NREL’s Outdoor Test Facility (OTF) in June 2000. In situ electrical performance and energy production from these modules obtained under ambient conditions in the field between June 2000 and August 2001 are compared. The average effective efficiency—derived from module energy out divided by solar energy in calculations averaged on a weekly basis—is analyzed and compared with module current-voltage measurements performed at standard reporting conditions (SRC). The effective efficiencies exhibit seasonal variations correlated with average module temperatures—becoming larger at colder temperatures. The performance ratios (PRs) defined as the effective efficiency divided by the efficiency at SRC, range from 78% to 96%, depending on the module and time of the year. The PRs exhibit seasonal variations that range from 11% to 15%.
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