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Power storage units in test: Fronius and BYD are again test winners

Energy storage

The current Electricity Storage Inspection 2021 analysed and compared the energy efficiency of 20 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.

Home storage for solar energy - is it worth it?

Before going into the detail, let’s consider two further questions that you may be asking yourself:

  • Why should I invest in PV storage?
  • And does it make financial sense?

The first question is very easy to answer: a PV system only generates electricity during the day. On sunny days, however, it will usually generate so much electricity that even a household with an intelligent energy management system.will not be able to use all its self-generated solar power itself. The surplus energy is then fed into the public grid, though feed-in tariffs are getting lower all the time. 

During the night, by contrast, expensive electricity is drawn from the public grid. A home storage unit also enables you to use self-generated solar power at night. 

Another factor in favour of investing in a solar battery is that it provides electricity during a blackout. Note, however, that not all storage systems can be recharged while operating in backup power mode. You can find out more about storage units and backup power in the interview with our storage expert, Susanne Lampl.

A PV storage unit has many advantages:

  • You can use your self-generated electricity during the night as well – saving yourself expensive energy costs while doing something good for the environment
  • The right PV storage unit makes you self-sufficient and provides you with a backup in the event of a blackout

The more efficient the system, the more cost effective it will be – do the numbers

The answer to the question regarding the financial viability of a home storage system will not be the same for every system. As well as other factors, one of the most important criteria determining the cost effectiveness of a PV system is the efficiency of the battery. Efficient home storage systems have low conversion losses – in other words, far less electricity is lost during storage and discharging. The upshot of this is that more of the generated kilowatt hours can actually be used. 

The result of the solar battery test carried out by HTW Berlin revealed that, compared to the other systems, the winning Fronius Symo GEN24 Plus and BYD Battery-Box system made an extra 600 kilowatt hours a year available to the electrical loads.

The home storage system from Fronius and BYD – there’s never been a system as powerful as this one

In addition to conversion losses, other technical factors, such as energy management and standby mode, all play a part in the System Performance Index (SPI). The Fronius Symo GEN24 10.0 combined with a BYD high-voltage battery achieved an SPI of 94%, and is the only one with a Class A energy efficiency rating.

The best performance ever measured in the solar battery test. The system also came an excellent second in the 5 kWp category, and with an SPI of 92.3% was only 0.3% behind the first-placed home storage system.

Boost in efficiency with Multi Flow Technology

Its integrated Multi Flow Technology is partly responsible for the outstanding test result of the GEN24 Plus. This technology ensures that the inverter is able to handle simultaneous energy flows in all directions, meaning that electricity can be used by the household while the battery is being charged at the same time.

GEN24 Plus – An all-rounder, even without its home storage unit

The proven Fronius Multi Flow Technology is not the only highlight that this newcomer to the Fronius inverter range has to offer. The GEN24 Plus will help you bring about your own energy revolution:

  • It charges your electric car and your energy storage unit with self-generated solar power.
  • When combined with a storage unit, the inverter can use its sophisticated backup power function to supply your entire household, even if the grid goes offline.

Thinking about investing in a PV system or expanding an existing one?
Find answers to all your questions about photovoltaic systems and energy storage units here. 

Solar battery test


  • Fronius and BYD were joint winners in the solar battery test organised by HTW Berlin

  • The Fronius GEN24 Plus and the BYD Battery-Box emerged as the most efficient home storage system, so make sense from a financial perspective as well.

  • A genuine all-rounder, the GEN24 Plus has to be the inverter of choice for your energy revolution.

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