Measured Module Performance Variation and the Opportunity for Distributed Power Electronics: Analysis of 27 PV Arrays in the Southwestern U.S.

A custom multitracer system has been designed to collect simultaneous, module-level I-V curves over an entire array. This system is used to acquire high and low light module performance data for over 500 modules, deployed in 27 arrays including six different PV technologies in the Southwestern U.S. The modules' current and voltage parameters show relatively little variation in arrays which are five years old or newer, but in older arrays the mean absolute deviation of maximum power between modules may approach 20% or more. Individual module performance models are created from the data and incorporated into hourly energy simulations for each array. Annual mismatch loss (and thus potential for increased energy capture using distributed power electronics) is found to be minimal, less than 1% for most arrays, but in several it is as high as 1-3% when simulated in their installed configurations. Factors contributing to mismatch loss are analyzed, including investigation of the impact of array orientation, size, module ordering, and string wiring configuration. Varying these factors has little impact on some arrays, but on one it creates scenarios in which the annual mismatch losses may exceed 10%.