KOSTAL Pressebereich
Hagen, Germany, 27.11.2018

We have won the test of the efficiency of PV storage systems

The highest system efficiency is offered by our PV hybrid inverter PLENTICORE plus 5.5 in combination with the BYD Battery-Box H11.5.

  • Highest system efficiency with a System Performance Index (SPI) of 91.4%
  • Electricity cost savings of approx. 1,107 Euro per year as well as optimum system and acquisition costs
  • Yield-increasing features such as self-learning shadow management


With a System Performance Index (SPI) of 91.4% our DC-coupled storage solution is a step ahead. This was scientifically confirmed by the current study "Stromspeicher-Inspektion 2018" by the Hochschule für Technik und Wirtschaft (HTW) Berlin*.

It's nice for us, but what does it mean to you?
With our storage system consisting of the PLENTICORE plus 5.5 and the BYD Battery-Box H11.5 you save the most electricity costs per year in comparison with other storage systems.

But there is another financial advantage that our storage solution provides you with: Compared to other systems that require two inverters, our combination does not require any additional devices, because the PLENTICORE plus takes over the energy management for the PV system and the battery at the same time. This saves you initial investment costs.

In a special print of the photovoltaik you can find out more about the test winner.

Here are the results of the study*

*More details: www.stromspeicher-inspektion.de

The System Perfomance Index - What is it? 

The study determines the System Performance Index (SPI). This provides an economic value that describes the possible reduction in electricity costs per year by using the considered PV storage system.

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 shy of €100 off an ideal system under real conditions. A house consuming 5,010 kilowatt hours of electricity 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.


Aroused interest? Than find out more here.