Home Battery Warranty Checklist: What to Ask Before You Buy
- Compare years, the cycle or throughput limit, and the capacity left at the end together.
- Ask who honours a claim: the manufacturer, the installer, or a third-party guarantee.
- Check the conditions. One datasheet we read ties the full warranty to a reliable internet connection.
- Ask whether labour, removal and reinstallation are covered, and whether the inverter has its own warranty.
- Ask in writing whether the warranty transfers if you sell the house.
A home battery warranty is a bundle of limits, not a single number. Before you sign, ask for the full document and check seven things: the term, the cycle or throughput limit, the capacity left at the end, who pays, what is covered, what can void it, and whether it passes to the next owner.
The three limits: years, cycles and throughput
Start with the term in years, then look for a second limit. Some makers state a number of cycles, some a total energy throughput, and some say cycles are unlimited. Whichever limit you reach first usually ends the cover. Our explainer on warranties and cycle counts shows how to turn your own daily use into cycles per year.
Two datasheets show how different the wording can be. GivEnergy's Giv-Bat 9.5 Gen 3 datasheet lists unlimited cycles over 12 years. Tesla's UK Powerwall 3 datasheet lists a 10-year warranty. Neither document gave a cycle or throughput limit, so for Tesla you would need to ask whether one applies.
Capacity left at the end
A battery loses some capacity with use, so a good warranty says how much it should still hold when the term ends, usually as a percentage of the original, for example 70%. A long term with no stated figure tells you little.
In the two datasheets above we could not find a retained-capacity figure. That does not mean there is none, only that it was not on the document we read. Ask the installer for the figure and for how it is measured. If the battery will have lost capacity by then, also check that the size you buy still covers your needs, using the capacity guide.
Who pays, and what is covered
The name on the warranty is not always the company that will fix the problem. Ask who handles a claim, and what happens if your installer stops trading. The installer checks in our quote guide help you compare this between bids.
- Does the warranty cover the replacement part only, or also labour?
- Are removal, reinstallation and shipping included?
- Does the inverter have its own warranty, with its own term?
- Is there a separate warranty for the installation work?
Keep the paperwork
Save the full warranty document, the installer's name and the commissioning date together. If a claim comes up in year eight, you will need all three.
What can void or limit the cover
Read the conditions section line by line. Tesla's datasheet says the Powerwall 3 must be reliably connected to the internet to secure the full 10-year warranty, and that cellular should not be the primary connection. That is a real, practical condition: a weak Wi-Fi signal in the garage becomes a warranty question.
Other conditions to look for, which vary by maker and which we have not confirmed for every brand:
- Installation by an approved or certified installer.
- Registration within a set time after installation.
- Operating temperature, location and ventilation.
- Firmware updates and connectivity.
- Extra use, such as grid services or heavy tariff trading, if the terms count it.
If you sell the house
Ask in writing whether the warranty passes to the next owner, and whether they must register. A transferable warranty is easier to explain to a buyer, and a hard-to-transfer one is worth knowing about before you pay.
Common questions
Is a longer warranty always better?
Not on its own. A shorter term with generous cycle limits and a clear retained-capacity figure can be worth more than a longer term with tight limits. Compare all three together.
Does the inverter have the same warranty as the battery?
Not necessarily. The inverter often has its own term, so ask for both in writing. Where a battery has a built-in inverter, check whether one warranty covers both.
What if my installer goes out of business?
It depends on who stands behind the warranty. Ask whether the manufacturer's cover continues and whether a third-party guarantee is offered, before you sign.
Where can I find the warranty terms?
On the datasheet and in the full warranty document. Not every datasheet gives all the terms: the two we read did not state a retained-capacity figure, so ask for the document itself.
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