Fronius International GmbH has issued new international limited warranty conditions for its battery products, covering the Fronius Reserva and Fronius Reserva Pro ranges. The conditions apply to covered products purchased on or after 1 March 2026, and replace the earlier terms for those purchases1.
The warranty is described as a limited, voluntary manufacturer's warranty granted by Fronius, running alongside statutory warranty obligations rather than replacing them1. It covers hardware only, naming the Reserva BMS and Reserva Module and the Reserva Pro BMS and Reserva Pro Module as covered products. Software and digital services are excluded, as are parts subject to regular wear and tear such as DC isolators, fuses and housing parts, and any components not originally placed on the market by Fronius1.
"The LIMITED WARRANTY applies to COVERED PRODUCTS purchased on or after March 1st, 2026."
The warranty period is ten years unless otherwise stipulated, and begins six months after initial delivery from Fronius1. The performance element warrants either a remaining battery capacity, expressed as a state of health percentage, or an energy throughput level, whichever is reached first, with the applicable figure depending on the country and product1. The throughput figures given for the Reserva range are:
| Product | Usable energy | Throughput |
|---|---|---|
| Fronius Reserva 6.3 | 6.31 kWh | 19.69 MWh |
| Fronius Reserva 9.5 | 9.47 kWh | 29.59 MWh |
| Fronius Reserva 12.6 | 12.63 kWh | 39.38 MWh |
| Fronius Reserva 15.8 | 15.79 kWh | 49.28 MWh |
| Fronius Reserva Pro 12.0 | 11.96 kWh | 53.57 MWh |
| Fronius Reserva Pro 16.0 | 15.95 kWh | 71.43 MWh |
| Fronius Reserva Pro 20.0 | 19.94 kWh | 89.29 MWh |
| Fronius Reserva Pro 24.0 | 23.93 kWh | 107.15 MWh |
The document lists a state of health figure of 80 per cent against the Reserva Pro 20.0 entry; the other rows in the source table carry throughput figures without a stated percentage1. The warranty is geographically limited to the countries set out in the document, and Fronius states it offers no warranty, express or implied, to countries not listed there1. For countries in country group 1 other than those specified, the document states that the "FRONIUS WARRANTY PLUS" model applies1.
Coverage requires that the product was bought new from Fronius, an authorised dealer or a professional installer, and was put into operation by a professional installer specialising in photovoltaic systems, following the Fronius operating and installation instructions1. Exclusions include damage from improper installation, inadequate ventilation, unauthorised repair or modification, power fluctuations, overvoltage, lightning, fire and water, and failure to charge the product within 14 days at a state of charge of zero per cent1. Where a product is repaired or replaced, the replacement carries the remainder of the original warranty period, which does not restart1.
Why it matters for households
A home battery's warranty is one of the few things that determines how much of a household's stored energy remains usable, and at what cost, over the life of the system. Two features of this document shape that in practice. The first is the throughput limit: the warranty is tied to total energy cycled through the battery, not only to elapsed years, so a household that charges and discharges heavily may reach the limit before the ten-year period ends. The second is the six-month lag before the warranty period starts, which runs from delivery from Fronius rather than from installation.
The conditions also place the installation itself inside the warranty terms. Cover depends on commissioning by a professional installer working to Fronius instructions, and the warranty does not extend to the installer's workmanship or to third-party equipment. For a household weighing home battery warranties, the distinction between product cover and installer liability is the practical one, and it sits alongside the wider question of what manufacturer warranties on home energy equipment typically include. The Reserva range itself is set out in the site's page on Fronius home batteries.
What happens next
The conditions apply to covered products purchased on or after 1 March 2026. Fronius states it may change the warranty conditions at any time at its sole discretion, with changes effective for purchase contracts concluded after the date of the change, and that the applicable conditions are those valid in the country of first commissioning at the time the purchase contract is concluded1. No further dated steps have been reported.
Sources1 cited
- SE_ToW_Battery_EN.pdf, fronius.com