Power conditioner efficiencies and annual performance analyses with partially shaded photovoltaic generators using indoor measurements and shading simulations

Partially shaded rooftop photovoltaic systems operate with non-uniform 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 depends on the site-specific details of the installation. To investigate this, power optimizer and string inverter efficiency measurements were conducted in the ZHAW indoor laboratory. With these results, simulations were performed for a module-level power electronics system, for which power optimizers were used at every module, and a standard string inverter photvoltaic system. As a performance comparison, the P370 power optimizer and 3500H inverter was used for the module-level power electronics system and partial shading by a chimney was considered. For the standard string inverter system, the string inverter SUN2000- 3.68KTL-L1, without the use of module-level power electronics was chosen. The results of the annual simulations showed 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