Performance of power optimizer versus string inverter systems

The ZHAW IEFE is involved in the performance research of power optimizer systems, which is funded by the Swiss Federal Office of Energy. The ZHAW PV shading simulation tool was compared to commercial tools, which show forecasts of additional yield by power optimizer systems with percentages in the double digits (PVSyst: 7.2% | PVSol: 14.6 %) relative to the SINV system for the heavy shading case. The reason for this is the use of the manufacturers’ data-sheet values, whereas the effectively measured power optimizer efficiency is generally 1.0 to 2.5% lower in points relevant for real-life operation. Finally, according to the results a list of performance-based recommendations for the application of the different PV systems was formulated.