According to a company press release, VARTA pulse is the most efficient AC-coupled energy storage system for photovoltaic systems with five kilowatt peak. This result was found by the 2020 energy storage system inspection by the Berliner Hochschule für Technik und Wirtschaft (HTW Berlin). In the context of the study, researchers investigated the energy efficiency of 21 storage systems for solar power systems. In addition to the overall efficiency, the energy storage units from VARTA score well thanks to a battery efficiency of 98 percent. The energy storage system also gained best marks in standby mode: the system only consumes two watts of energy when it is not in operation.
In the study, HTW Berlin’s research group compared various system properties that have an effect on the overall efficiency of the device. Efficiency is a determining criterion in the evaluation of storage systems for photovoltaic systems because the more efficiently an energy storage system works, the higher the return for the home owner and the contribution to climate protection. For a high level of efficiency it is crucial that storing solar power consumes as little energy as possible. The degree of efficiency is an important performance indicator: the VARTA pulse average battery efficiency at 98 percent shows that there is only a very low loss of energy when it is converted in the energy storage unit. The results show the highest battery efficiency ever recorded in the course of the energy storage system inspections.
A further performance indicator from the study is standby power. Just like many household devices, the energy storage units also need energy for the most important functions even when they are not in operation. The lower the energy consumption, the more efficient the storage unit. VARTA pulse consumes two watts in both the discharged and fully charged standby status, for which the energy storage system also gets top marks. “We are continually working on making our energy storage units as efficient as possible. The study shows that we are being successful. It is now important to further exhaust this potential,” says Bengt Stahlschmidt, General Manager Energy Storage Systems at VARTA.
VARTA pulse scores well for overall efficiency
In addition to the individual system properties, the overall efficiency of the storage units is reflected on the basis of a single performance indicator, the system performance index (SPI). The SPI compares the actual cost saving with he theoretical potential savings of a completely loss-free system in an average household. VARTA pulse’s SPI for an average rooftop system with five kilowatt peak is 90.5 percent, which means it is the best of all the tested AC-coupled systems. The energy storage units were also tested for larger photovoltaic systems: for a 10 kilowatt peak solar power system including a heat pump and an electric car, VARTA pulse achieved an SPI of 92.4 percent. Also in this regard, the device was one of the best.
It was for the third time that HTW Berlin performed the energy storage system inspection, which is co-funded by the Deutsche Bundesstiftung Umwelt (BDU – German Federal Environmental Foundation). Storage systems from 14 companies were tested by independent test labs this year. The study does not only show the energy efficiency of individual storage systems but it is also considered as a market overview for the German solar power storage system sector. “We are really pleased that through our VARTA pulse energy storage unit we are at the top of the table. It shows that our customers can rely on the quality of our ‘Made in Germany’ energy storage systems,” says Bengt Stahlschmidt. VARTA produces its energy storage units at its facility in Nördlingen, in Southern Germany. “In doing so, we guarantee our customers short and efficient routes and faster delivery times,” Bengt Stahlschmidt continues.