The performance of a photovoltaic (PV) system is affected by the particular mounting configuration selected. But the optimal configuration for various potential designs is unknown because too few PV systems have been fielded. Sandia National Laboratories (SNL) is currently conducting a controlled field experiment in which four of the most commonly used module-mounting configurations are being compared. The data from the experiment are used to verify the accuracy of PVFORM, a new PV performance model. The model is then used to simulate the performance of PV modules mounted in different configurations in eight sites throughout the US. This paper describes the module-mounting configurations, the experimental methods used, the specialized statistical techniques used in the analysis, and the final results of the effort. The module-mounting configurations are rank ordered at. each site according to their energy production performance, and each is briefly discussed in terms of its advantages or, disadvantages in various applications.

Units: SI