Fronius GEN24 in the UK: backup, batteries and warranty

Fronius is worth comparing if you want to decide separately on solar, a battery and backup during a power cut, and your quote spells out each one. The GEN24 and GEN24 Plus don't do the same jobs: the Plus can run a compatible battery, and the backup you get depends on the model and the equipment added. Fronius's warranty for inverters bought in the UK from 1 June 2026 runs for 10 years, but only if the inverter is registered on Fronius Solar.web within 30 months of leaving the factory, and full labour cover lasts for the first five.

Fronius at a glance

Primo, Symo, GEN24 and Plus

Fronius sells the Primo GEN24 for single-phase supplies and the Symo GEN24 for three-phase. Your supply decides which. An older Fronius range doesn't gain GEN24 features.

Figures from Fronius's Primo GEN24 and GEN24 Plus datasheet (June 2025 edition, linked from Fronius UK):

Fronius now also sells a GEN24 SC generation, which it says handles higher panel currents and has built-in arc-fault protection; ask which generation your quote includes.

In Great Britain, a Fronius system counts as G98 if its inverters add up to no more than 16 A per phase, which is 3.68 kW on a single-phase supply or 11.04 kW on three phases; the installer then notifies the network operator within 28 days. Bigger systems go through G99, with approval needed before connection. The ENA type-test register lists the Primo GEN24 3.0 and 3.6 under G98 and the 4.0 to 6.0 under G99, and the three-phase Symo GEN24 3.0 to 10.0 under G98, all as compliant for solar-only operation. For battery operation the register lists separate 'Energy Storage' records, and for the Symo GEN24 3.0 to 5.0 those show 'Non-compliant' with no reason given, so if your quote pairs a three-phase GEN24 Plus with a battery, ask the installer which register record covers it. Northern Ireland uses G98/NI and G99/NI.

Two inputs of different sizes

A maximum power point tracker (MPPT) gets the best output from one group of panels. The Primo GEN24 has two, and they aren't equal: the datasheet allows up to 22 A on the first and 12 A on the second. So the first suits the larger roof face. If you have an east and a west face, ask which goes on which input and for the predicted yield of each.

Shade from a chimney isn't solved by the inverter brand. Keep panels out of lasting shade first, then compare designs.

PV Point: one socket, while the sun shines

Fronius describes PV Point as basic backup built into every GEN24: a separate socket that works in a power cut even without a battery, while the panels produce enough. The datasheet gives 3,000 VA and a switch-over of under 15 seconds, so it is not an instant supply. It doesn't power your other sockets. At night or under heavy cloud, without a battery, it has nothing to give. Ask where the socket will be and what you can plug into it, and see it working at handover.

Full Backup needs a full design

Full Backup can keep chosen circuits, or the whole home including large loads, running when the grid fails. Fronius says it needs an eligible GEN24 Plus, a battery and an external switching device that separates your home from the grid safely. It is not available on the Symo GEN24 3.0 to 5.0 Plus, so check this first if you have a three-phase supply. The datasheet gives a switch-over of under 10 seconds.

"Whole home" doesn't mean unlimited power. On a 5.0 Plus, backup is rated at 5,000 VA, so a heat pump, hob and car charger together can exceed it. Ask the installer to list the essential loads and their start-up draw, and agree the battery reserve kept for power cuts. Our guide to solar panels in a power cut explains why a grid-tied system normally switches off.

A battery now or later

The GEN24 Plus takes a battery directly. The datasheet lists Fronius Reserva, BYD Battery-Box Premium HVS/HVM and LG FLEX, but adds that compatibility depends on country-specific certification. UP.storage is a software upgrade that adds a battery connection to a GEN24, sold in Fronius's webshop "in selected countries", so get written confirmation that it's available for your model in the UK before relying on it.

Fronius's own Reserva battery comes in four sizes from 6.3 to 15.8 kWh usable. Its UK warranty lasts 10 years but starts six months after Fronius delivers it, not when it is installed. It covers 80% of usable capacity or a fixed throughput, whichever comes first: 29.59 MWh for the 9.5 kWh size, about 3,100 full cycles. Our solar battery guide explains how to size one to your evening use.

The Fronius warranty in the UK

Fronius's international warranty conditions (edition EN_0326) apply to inverters bought from 1 June 2026, with the UK in its first country group:

• Registration is a condition. The inverter must be registered on Fronius Solar.web within 30 months of leaving Fronius's factory, or the warranty doesn't apply.
• Years 1 to 5 (Warranty Plus): a replacement or repaired unit, standard shipping, and the labour to remove and refit it, when done by Fronius or an installer it appoints.
• Years 6 to 10: the part only. Labour, call-out and shipping are yours to pay.
• Never covered: travel costs, and faults from missed software updates, poor ventilation or poor installation.
• Selling your home: the cover passes to the new owner.
• Extension: you can buy cover up to 15 years, within six months of the warranty starting.

The terms fall under Austrian law but keep the consumer protections of the country you live in. After year five a failed inverter still means paying someone to swap it, so ask whether your installer's own workmanship guarantee covers that visit. Under the Consumer Rights Act 2015 your claim for a faulty or badly fitted system lies with the business that sold it, and RECC or HIES membership adds a dispute route; MCS certification alone doesn't show whether an installer belongs to either, so check before you choose an installer.

Monitoring and where it goes

Fronius Solar.web shows production and, with a Fronius Smart Meter fitted, your use and exports. At handover, ask for an owner login and check that the data updates. The GEN24 has active cooling and a datasheet noise figure of under 42 dB(A), so avoid a spot next to a bedroom and keep the clearances in the manual. Solar panel monitoring explains what to watch through the seasons.

Comparing two Fronius quotes

A quote with Full Backup and one with PV Point don't give you the same thing; our guide to comparing solar quotes sets out a like-for-like check. Before signing, get in writing:

1. the Primo or Symo model, its size, GEN24 or GEN24 Plus, and generation;
2. the string plan and which roof face goes on which input;
3. the backup included (PV Point or Full Backup) and the circuits it covers;
4. the battery and switching device, if Full Backup is promised;
5. whether the inverter size means G98 notice or a G99 application, and any export cap the operator sets;
6. who registers the inverter on Solar.web, and who handles claims.

A GEN24 system supplied and fitted by your installer, battery included, has 0% VAT until 31 March 2027, then 5% unless the relief is extended. In Great Britain, exports are paid by electricity suppliers through their own Smart Export Guarantee tariffs, each with its own rate, and they need the installation's MCS certificate (or equivalent). Our calculator estimates a system size for your roof; for an alternative, see SMA.

Frequently asked questions

Does PV Point work without a battery?

Yes, on its own socket, while the panels produce enough. At night without a battery it can't supply anything.

Can every GEN24 Plus do Full Backup?

No. Fronius excludes the Symo GEN24 3.0 to 5.0 Plus, and Full Backup always needs a battery and an external switching device.

Is the Fronius warranty 10 years in the UK?

Yes for inverters under 50 kW bought from 1 June 2026, if registered on Solar.web within 30 months of leaving the factory. Only the first five years include labour.

Does a Primo GEN24 5.0 need DNO approval?

In Great Britain, on a single-phase supply, yes. Above 3.68 kW the installer must apply under G99 and get approval first; the 3.0 and 3.6 models can connect under G98 and be notified afterwards.