Last reviewed: 6 September 2026. How to read a domestic battery warranty
document before you sign. General information, not legal advice; the terms that bind you are the ones in
your own document, which is why this page is about how to read it rather than what it says.
A battery warranty is a promise with four numbers, three exclusions and one question nobody prints on
the front page. Salespeople quote the first number. The refusal, when it comes, will cite one of the
other things.
Read the document before you sign the contract, not after the battery is on the wall. Any installer
who cannot produce it before purchase has told you something.
The four numbers, and the word “whichever”
| Limit | What it is | What burns through it |
|---|---|---|
| Years | A calendar limit, commonly ten | Time. It runs whether you use the battery or not |
| Cycles | Full charge-discharge cycles allowed | Daily arbitrage — see charging on a cheap night tariff |
| Throughput | Total energy allowed through the battery, often in MWh | Heavy use of a large battery; it is the limit that bites on high-capacity systems |
| End-of-life state of health | The capacity floor guaranteed at the end — a figure typically between 60% and 80% of original |
Nothing; it is the threshold at which a claim becomes valid |
The key word in the document is “whichever occurs first”. Your ten-year warranty
ends the day you hit the cycle or throughput limit, which for a hard-working arbitrage system can be
years early. Do the division before you buy: divide the throughput allowance by the energy you plan to
push through annually, and see which limit arrives first. If it is not the years, the years figure is
marketing.
Whose promise is it?
This is the question the front page never answers clearly, and it decides everything.
- The manufacturer’s product warranty covers the hardware. It is a promise by a
company that may or may not exist in year seven. - The installer’s workmanship warranty covers their work — the fixings, the
wiring, the commissioning — and is a separate promise with a separate duration. - An insurance-backed guarantee covers the installer’s workmanship promise if the
installer ceases trading. It rarely covers the product itself: insurance-backed guarantees explained. - Your statutory rights are owed by the retailer under the Consumer Rights Act
2015 and cannot be signed away by any of the above — the framework in warranties and your UK rights.
When GivEnergy entered administration in April 2026 the first of those four evaporated and the other
three did not. That is the practical case for reading which is which.
The exclusions that actually get used
- Labour, carriage and access. The commonest and most expensive exclusion: the
manufacturer supplies a replacement module and you pay the electrician to fit it. Check whether labour
is covered, by whom, and for how long — it is often shorter than the parts cover. - Connectivity requirements. Some warranties require the system to remain connected
to the manufacturer’s monitoring platform, so that they can see the data. A battery offline for six
months can be a battery outside warranty. This clause is easy to breach by accident when a router is
replaced. - Operating conditions. Ambient temperature limits, ventilation clearances, humidity
and altitude. This is where a loft installation, or a cupboard built around the unit, quietly voids the
cover — another reason siting matters: where a
battery can be installed. - Unapproved installation or modification. Installed by someone outside the approved
network, or controlled by third-party software, and the cover can go. Worth knowing before you connect
an open-source controller. - Pro-rata settlement. Some warranties pay a declining proportion by year rather
than replacing the unit. A year-eight claim can be worth a fraction of the replacement cost.
Six clauses to find before you sign
| Clause | Why it matters |
|---|---|
| Transferability | Whether the warranty passes to a buyer of the house, and whether a fee or a notification period applies. It affects resale value |
| Measurement method for state of health | How capacity is proven in a claim. If only the manufacturer can measure it, and the manufacturer is gone, the clause is unusable |
| Registration requirement | Many warranties require registration within a set period after commissioning. Miss it and you may have nothing |
| Governing law and jurisdiction | A warranty governed by foreign law and enforceable abroad is a warranty you will not enforce |
| Who to claim from | Some route everything through the installer. If the installer has failed and the manufacturer will not deal with you directly, you have a gap |
| Exclusion of consequential loss | Standard, and worth knowing: nobody is compensating you for the electricity you did not save while the unit was down |
How to make the warranty claimable
- Register it immediately after commissioning, and keep the confirmation.
- Keep the document pack: invoice, contract, commissioning record with serial numbers, electrical
certificate, network notification. - Record capacity once a year, the same way each time, and keep the readings. Evidence of gradual
decline is what turns a state-of-health claim from an opinion into a case. - Keep the system connected if the warranty requires it, and check after any router or broadband
change. - Do not modify the installation or add third-party control without checking the terms.
- Pay at least the deposit by credit card, so that section 75 sits behind everything else — section 75 claims.
What a warranty is worth in a payback calculation
Our editorial position, stated plainly: nothing that happens after year five should be
load-bearing in your arithmetic. If a battery only pays back on the assumption of a free
replacement in year eight, it does not pay back. Run the numbers assuming nothing is ever replaced, using
the battery payback calculator, and treat any warranty claim
that does come good as an unexpected bonus. That is also how to read the ageing question in how long does a home battery last.
Frequently asked questions
Is a 10-year warranty better than a 6,000-cycle one?
Neither, on its own. Convert both into your own usage: cycles you will actually do a year, energy you
will actually push through. The binding limit is the one that arrives first.
What is a “performance” or “capacity” warranty?
A promise that capacity will not fall below a stated percentage of original within the term. It is
only useful if the measurement method is defined and someone independent can apply it.
Does the warranty transfer if I sell the house?
Sometimes, sometimes with a fee, sometimes not at all. Check the clause — a transferable
warranty and a full document pack are worth real money at sale.
What if the warranty document contradicts what the salesperson said?
The document governs the manufacturer’s promise. A specific claim made to induce the sale can still
matter under consumer law as a misrepresentation, which is a reason to keep marketing material and
emails. Get anything you are relying on written into the contract.
Sources.
Consumer Rights Act 2015 ·
Consumer Credit Act 1974, section 75 ·
Citizens
Advice consumer help.
The clause checklist and the payback position are our own editorial judgement — see editorial methodology.