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Solar power ensures a seamless energy supply even during a power outage

PV Basics

It’s usually when you least expect it, just when you are in the middle of cooking, surfing the internet or watching your favourite film – suddenly the power goes out. It’s in moments like these that a photovoltaic system with backup power function comes into its own. Let us show you how it works and everything it can do.


Unlike a PV system without a backup power-capable inverter, a photovoltaic system with backup power function means you can also generate and use energy during a power outage. A system without a backup power option switches off when it is disconnected from the grid and is therefore unable to generate any energy.

Using solar power even during a power outage – how does it work?

If you have a PV system with backup power function, then you have opted for a worry-free package. If there is a power outage, a signal is sent to the backup power-capable inverter which then disconnects from the grid and switches to ‘stand-alone operation’. This means the photovoltaic system is able to continue to generate energy independently. During the day, you will be supplied with energy directly from your system as normal. 

If you also have an energy storage system, you can store excess energy and continue to draw energy in the evening or when it is very cloudy. As soon as power is restored, the Fronius Smart Meter detects this and gives the ‘command’ to connect to the grid. At this point, you can draw power from the grid again or feed it in as required.

More infos from our storage-expert

It all depends on the inverter

It’s important to note that not all photovoltaic systems automatically continue to generate energy during a power outage. Systems with ‘PV only’ inverters lack additional components such as relays or mains protection, which means they cannot establish a stand-alone network. However, if you have a hybrid inverter with a backup power function, then you are equipped for all (power outage) scenarios. Fronius offers the GEN24 Plus and Symo Hybrid backup power-capable hybrid inverters, for example.

There are also differences when it comes to the energy storage systems: Not all batteries are compatible with backup power-capable hybrid inverters, and are able to store energy in the event of a power outage. Fronius uses Multi Flow Technology in its selected hybrid inverters, which enables the battery to recharge even in the event of a power outage. Fronius is one of just a few companies to offer this backup power package.

What is an inverter?

‘Full Backup’ and ‘PV Point’

Supplying an entire household in the event of a power outage – including three-phase loads such as electric cookers or heat pumps is also referred to as ‘Full Backup’ by Fronius. This is most useful when combined with a battery. 

For those who would like to start with something a bit smaller, the Fronius GEN24 Plus also offers a special basic backup power option, called ‘PV Point’. In this case, a socket in the house is directly controlled by the inverter and then (only) supplied in the case of a power outage. This option is an inexpensive solution if you only need one source of power and don’t require any additional installation work in the switch box – as is the case with the ‘Full Backup’.

PV systems with backup power function pay off in the event of a power outage

Inverters with backup power function make sense for everyone. When the power goes out, you are limited in what you can do at home or in work. A PV system with backup power function has you covered. It gives you peace of mind that, even if there’s a power outage, your ice will remain cool in summer when it’s hot and your feet will stay warm in winter when temperatures drop below zero. A hybrid inverter is also worth considering for other scenarios too.

Statistics show that there were 168,000 power outages in Germany in 2018, lasting an average of 14 minutes (source: Bundesnetzagentur Deutschland [German Federal Network Agency]). A photovoltaic system with backup power function means you can bridge small outages such as those, without even noticing. And with an additional storage system, you’ll never be left sitting in the dark, even if there’s a power outage.

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