Independent testing institutes test the overall efficiency of storage systems, analyzing the interaction of the PV system and battery storage. Two different reference cases are used for the evaluation.
The first reference case analyzes the System Performance Index (SPI) for a 5-kW PV system with annual household consumption of 5,010 kWh/a, while the second reference case combines a 10-kW PV system with heat pump (2,664 kWh/a) and electric car (1,690 kWh/a), and annual household consumption of 5,010 kWh/a.
TWO REFERENCE CASES, TWO TOP RESULTS
» Using the System Performance Index, anyone can immediately see which system is most efficient and how much energy each system actually provides. «Pfaffenbichler Dominik, Development at Fronius International
Why is the System Performance Index (SPI) determined during the Energy Storage Inspection so valuable? Why should installers and consumers also pay attention to the SPI? And what makes Fronius inverters so successful in the Energy Storage Inspection?
Dominik Pfaffenbichler, who works in Development at Fronius International offers exciting answers:
DP: What’s really great about the SPI is that it doesn’t just take the conversion efficiency of an inverter into account, but instead includes all the relevant losses of a storage system, which makes it possible to achieve a holistic analysis and to fairly compare different systems.
DP: Any inverter manufacturer. The only important thing is that measurements are done at an independent testing institute using series production (hardware and software), and that the deadlines are met.
DP: Changes were made to general conditions, such as elimination of the 70% feed-in limit, as well as the difference between feed-in tariff and grid purchase price. The SPI has always been dynamic and takes into account user scenarios as well as feedback from us participants to improve the methodology
DP: A lot of hard work has gone into that. We analyze the SPI as well as the results from each Energy Storage Inspection and incorporate all findings into the (further) development of our hardware and software. We never stop optimizing our system.