Fronius GEN24 Plus during a power cut: PV Point and Full Backup explained

A conventional grid-connected inverter disconnects as soon as the grid fails: this is mandatory for safety reasons. The Fronius GEN24 Plus They feature two backup functions that ensure you still have electricity during a power cut: PV Point y Full Backup. They differ in terms of scope, cost and installation.

PV Point: basic emergency mode without a battery

PV Point is a dedicated power socket which comes directly from the inverter. When the mains supply fails, the GEN24 switches that output within a few seconds and supplies it with solar power (and from the battery, if one is fitted).

Maximum power: 3 kW single-phase (230 V).
It only works without a battery whilst the sun is shining and production exceeds consumption at the tap.
When running on battery power, it operates day and night until the reserve SOC is depleted.
It doesn’t power the whole house: just whatever you plug into that socket (fridge, router, light, mobile chargers).
It requires a socket to be fitted by the installer on the PV Point terminals of the inverter. No work is required on the distribution board.

It is the most cost-effective option: it is included in all GEN24 Plus units and all you need to do is wire up the socket and enable it in the settings (Device settings → Functions and I/O → PV Point).

Full Backup: a comprehensive backup for your home

Full Backup turns the GEN24 Plus into a fully-fledged backup system: when the mains power fails, the inverter isolate the installation from the mains supply and supplies power to the whole house (or selected circuits), forming its own network.

Requirements:

Compatible high-voltage battery: BYD Battery-Box HVS/HVM, Fronius Reserva or equivalents from the Fronius list. See batteries for the GEN24 Plus y Fronius Reserve.
Switch box (Fronius Backup Box, Enwitec or similar) which physically disconnects the grid and switches the power supply to the home to the inverter.
Fronius Smart Meter installed at the connection point.
Back-up power is limited to the inverter’s rated power (Primo, GEN24: 3–6 kW single-phase; Symo, GEN24: 6–10 kW three-phase) and to the battery’s maximum current.
In three-phase operation (Symo GEN24), the switchgear must switch all three phases and the inverter generates a balanced three-phase network.

Advantages: automatic switching (between 60 seconds and a few seconds, depending on the settings), solar battery charging during a power cut, automatic return to the mains when power is restored. Disadvantages: the cost of the unit and installation, and the battery must be sized to last through the night.

Which one to choose

Situation	Recommendation
Occasional power cuts – do you want to keep your fridge and communications running?	PV Point
A home without a battery and on a tight budget	PV Point (operates during the day)
An area with frequent power cuts or where people work from home	Full Backup with battery
Water pumps, heating systems or critical three-phase loads	Three-phase full backup (Symo GEN24 Plus)
Actual off-grid installation (not connected to the mains)	It is not the product: use a Victron inverter-charger

Configuring Full Backup on the inverter

1. GEN24 web interface (Technical mode) → Device settings → Functions and I/O → Backup mode: Full Backup.
2. Define the battery life (Minimum SOC reserved for power cuts, e.g. 20–30 %).
3. Configure the digital output that controls the switch box in accordance with the manual.
4. Test: switch off the main circuit breaker and check that the property is still powered and that “Backup mode active” appears on Solar.web.

Things you should know

During a power cut, the inverter can continue to generate electricity and charge the battery, but it does not feed electricity into the grid (obviously).
If the battery runs out overnight, the system switches off until the sun comes out or the mains supply is restored.
In Full Backup mode, the starting power of motors (pumps, compressors) may exceed that of the inverter: avoid starting several at the same time.
The GEN24 models without “Plus” do not have backup or battery management functions; the Plus feature can be purchased at a later date via a licence.

FV Componentes is Fronius authorised technical service centre (Fronius System Partner). If the problem persists after carrying out these checks, please open a ticket at Technical support with the serial number and a screenshot of Solar.web, and we’ll diagnose it.