The current Energy Storage Inspection 2022 analysed and compared the energy efficiency of 21 electricity storage systems. As in the previous year, Fronius and BYD are way out in front, taking 1st and 2nd place in the two test categories. Fronius is thus the only manufacturer of hybrid inverters to have achieved the highest efficiency rating in both categories. In this article, we show why the Fronius and BYD storage solution achieves the best results and how energy efficiency affects the profitability of photovoltaic systems.