What is the System Performance Index?
The study identifies the System Performance Index (SPI for short), which produces an economic value that describes how much could be saved in electricity costs a year when using the PV storage system in question.
The SPI is calculated from the real cost saving over the ideal cost saving. An ideal system with no losses whatsoever would produce an annual saving of €1,211 and would therefore have an SPI of 100 percent. KOSTAL’s highly efficient system is therefore only just over €100 shy of an ideal system under real conditions. A house consuming 5,010 kilowatt hours of power a year and fitted with a five kilowatt solar system provides the reference for the ideal system.
The SPI was conceived to allow the way in which the components (inverters/batteries/PV modules) available on the market interact in an overall system to be compared and therefore to improve transparency for the customer.
Further information can be found at www.stromspeicher-inspektion.de