Power Conditioner Efficiencies and Annual Performance Analyses with Partially Shaded Photovoltaic Generators Using Indoor Measurements and Shading Simulations

Partially shaded photovoltaic systems operate with nonuniform conditions within the photovoltaic array, which lead to power losses. Module-level power electronics can potentially improve the performance of such photovoltaic systems. However, the potential performance increase compared to standard string inverter systems is site specific. To investigate this, power optimizer and string inverter efficiency measurements are conducted in the ZHAW indoor laboratory. With these results, simulations are performed for a module-level power electronics system with power optimizers at every module and a standard string inverter rooftop photovoltaic system. As a performance comparison, the P370 power optimizer and 3500H inverter are used for the module-level power electronics system and partial shading by a chimney is considered. For the standard string inverter system, the string inverter SUN2000-3.68KTL-L1, without the use of module-level power electronics, is chosen. The results of the annual simulations show a gain of the module-level power electronics system between -0.9% and 1.4% (14 modules) or -0.2% and 0.8% (13 modules), depending on the position of the chimney. Furthermore, the shading adaption efficiency, a method of quantifying the annual performance for shading situations by applying weightings to a few indoor measured performance values of power electronic components, is described.