Last reviewed: 6 September 2026. A vetting checklist for domestic
battery installers in the UK. We are not installers, we do not put readers in touch with installers, and
we take no commission from any of them — see how we make
money.
The single most important decision in a battery purchase is not the brand of the cells. It is the
company whose name is on the contract, because that is who owes you a working system for the next
decade. British owners learned this the hard way in 2026: when GivEnergy entered administration in
April, the administrator’s answer to warranty questions was that consumers should approach their
installer. That answer only helps if the installer is still there.
So vet the installer harder than the product. Here is how.
Before the quote: five things to check yourself
- How long have they traded? Company records are free to search and show
incorporation date, accounts and any change of name. A firm trading under a new company number since
last year, with directors from a dissolved predecessor, is a pattern worth noticing. - Are they certified, and under which scheme? MCS certification, or an accepted
equivalent, plus membership of a consumer code such as RECC. What each one does and does not protect
is in MCS and RECC: what protection do they
actually give. - Are they insured? Public liability, and professional indemnity if they are
designing the system. Ask for the certificate, not a reassurance. - Who does the electrical work? A battery is fixed electrical work, notifiable in
England and Wales under Part P; Scotland and Northern Ireland have their own building standards. Ask
which competent-person scheme the electrician belongs to. - Do reviews describe the aftercare? Anyone can install neatly on a sunny day.
Search reviews for the words fault, callback, warranty and delay — that is the part you are
buying.
At the survey: the eight questions
| Question | What a good answer sounds like |
|---|---|
| What is the usable capacity, not the nameplate? | A specific kWh figure, given in writing, that is lower than the headline number |
| How did you size it? | From your consumption outside cheap or sunny hours — the method in what size battery do I need — not from what is in the van |
| Where exactly will it go, and what does the manual say about that location? | A named position, with clearances and a temperature rationale: where a battery can be installed |
| Who notifies the network operator, and will I get the acknowledgement? | “We do, and yes.” A battery system needs notifying; you want the paperwork |
| What exactly does your workmanship warranty cover, and for how long? | A number of years and a clear scope, distinct from the manufacturer’s product warranty |
| Is there an insurance-backed guarantee, and who underwrites it? | A named insurer and a certificate issued after installation: IBGs explained |
| Can the system be controlled locally if the manufacturer’s cloud service stops? | A straight yes or no. Evasion here is informative |
| What happens to my warranty if the manufacturer ceases trading? | Honesty: the product warranty is theirs, your contract is with the installer. Anyone who claims to guarantee a third party’s solvency is selling something |
Reading the quote
Three quotes on the same specification is the standard advice and it is right, but only if you can
compare them. Normalise them like this:
- Price per usable kWh installed, all-in. It is the only number that compares across
brands and sizes — the approach in home battery cost in the
UK. - What is included: inverter, meter or CT clamps, isolators, cabling, scaffolding
if any, making good, certification, network notification, commissioning and handover. - The savings claim. If a quote projects annual savings, ask what tariff, what
spread, what cycles a year and what round-trip efficiency were assumed. Then check it against our battery payback calculator, which defaults energy price
inflation to 0% and applies any inflation to off-peak rates too. Inflating only the peak rate is the
standard way to make a quote look good. - The VAT line. Supply and installation of a domestic battery is zero-rated under
the energy-saving materials regime until 31 March 2027, with or without solar. It then returns to
5%, not 20%. A quote or a sales pitch saying VAT is about to jump to 20% is either
wrong or pressuring you — see VAT on home batteries
explained.
Deposits, payments and the one move that costs nothing
Put at least the deposit on a credit card. Under section 75 of the Consumer Credit
Act 1974 the card issuer becomes jointly and severally liable with the supplier for the full purchase
price where the cash price is over £100 and no more than £30,000. A £200 deposit on a card protects a
£6,000 installation. It is the cheapest insurance available in this entire market and most buyers do
not use it — the mechanics are in section
75 claims.
Also: keep the deposit modest, never pay the balance before commissioning, and be wary of a
substantial discount conditional on paying in full up front. And treat a discount that expires today as
what it is. Pressure selling is a recognised problem in this sector, which is why consumer codes address
it.
The documents you should hold at the end
- The contract and the itemised quote.
- The electrical installation certificate and the building regulations notification.
- The network operator’s acknowledgement of the connection notification.
- The commissioning record, with serial numbers of every unit.
- The manufacturer’s warranty document and the installer’s workmanship warranty.
- The insurance-backed guarantee certificate, if there is one.
- MCS certificate or equivalent, if applicable to your installation.
- The manuals, including how to isolate the system safely.
Scan the lot the day the job finishes. This pack is what answers a loss adjuster after a claim, a
buyer’s solicitor at sale, and a warranty administrator four years from now — and it is exactly
what people cannot find when they need it.
Warning signs
- A price that expires at the end of the visit.
- A savings figure with no stated assumptions.
- “VAT goes to 20% in April” — it does not; it goes to 5%.
- Reluctance to put usable capacity in writing.
- No written answer on who notifies the network operator.
- A demand for full payment before commissioning.
- A brand-new company with no trading history and a deposit-heavy payment plan.
- Claims to guarantee a manufacturer’s warranty regardless of what happens to the manufacturer.
Frequently asked questions
Do I need an MCS-certified installer for a battery?
Not as a matter of law. It matters for scheme eligibility and it is a reasonable quality filter. For
a battery without solar there is no export payment to qualify for anyway — and a plug-in solar kit
is outside MCS territory entirely, which is why it cannot access the Smart Export Guarantee.
Should I use the manufacturer’s approved installer list?
It is a useful starting point and not a guarantee. Approval schemes are marketing arrangements as
well as quality ones, and they do not survive the manufacturer.
Is a bigger firm safer than a local one?
Not inherently. Longevity, insurance, an insurance-backed guarantee and clear paperwork matter more
than size. Several large installers have failed; plenty of small ones have traded for twenty years.
What if the installer goes bust after the job?
Then you fall back on the insurance-backed guarantee if there is one, section 75 if a credit card was
used, and the manufacturer’s product warranty for the hardware itself. That is three routes, which is
why we press so hard on all three: what to do if
your battery brand goes bust.
Sources.
Consumer Credit Act 1974, section 75 ·
Consumer Rights Act 2015 ·
HMRC VAT Notice 708/6 ·
Approved Document P.
The checklist is our own editorial judgement — see editorial
methodology.