Why heat pump installers should become battery installers too

MCS certified 36,000 home battery installations in the first half of 2026, almost double the same period last year. 92% of them went onto homes with solar. Heat pumps weren't what drove them.

That leaves an opening for the installers already fitting heat pumps. You're in the house when the homeowner is deciding how they'll heat it, and a heat pump gives a battery more work to do than almost anything else on the circuit.

The short answer

If you already fit heat pumps, you're most of the way there. To add batteries you need an electrical qualification for energy storage (usually the City & Guilds 2923-34), a DNO notification or application on every job, and training from the battery brand you choose. MCS certification under MIS 3012 isn't a legal requirement, but it's the standard the work is judged against. Quoted alongside the heat pump, a battery lets the homeowner run their heating on off-peak electricity, and on our costings it takes the total job from £13,150 to £18,338.

Why quote a battery alongside a heat pump?

A heat pump is the largest electrical load in most homes, and it's one that can be moved. The heat pump tariffs are built around that. Cosy Octopus sells electricity 51% below its day rate in three windows (04:00–07:00, 13:00–16:00 and 22:00–00:00) and charges 50% above it from 16:00 to 19:00. British Gas Heat Power takes 50% off from midnight to 07:00 and again from 13:00 to 16:00.

A heat pump on its own can shift some of its work into the cheap hours, heating the cylinder overnight or warming the house through the early afternoon. What it can't dodge is the early evening, when the house is losing heat and the family is home. A battery charged in the cheap windows runs the heat pump through that peak instead.

For the homeowner, that means buying less electricity at the day rate and more of it cheap. For comparison, the price cap unit rate for 1 October to 31 December 2026 is 26.32p/kWh, with VAT removed from electricity bills until 31 March 2027 (Ofgem).

The battery installation is zero-rated for VAT until 31 March 2027, including a battery charged from the grid with no solar at all. After that it goes to 5% (HMRC VAT Notice 708/6).

One check before you size anything: confirm the homeowner's tariff allows a battery to charge in its cheap windows. Not every heat pump tariff says, and Octopus doesn't publish a position for Cosy.

What does a battery add to the job?

Our own costings, built on MCS install-cost averages from 2022 to 2026, put a 5.8kWh battery at £8,251 as a standalone job and £5,188 when it goes in alongside a heat pump. One survey and one visit cover both, where a standalone battery needs its own.

For the homeowner, doing both at once is £3,063 cheaper than doing them in two visits. For you, it's an £18,338 job where it would have been £13,150.

For reference, the government's median for MCS-certified batteries in 2025/26 was £1,300 per kWh below 6kWh and £890 per kWh from 6 to 11kWh (DESNZ). The battery in our combined job works out at £894 per kWh, in line with the larger band.

What qualifications do you need to install home batteries?

The battery is electrical work, so the qualification is electrical. The recognised route is the City & Guilds 2923-34, a Level 3 Award in the design, installation and commissioning of small electrical energy storage systems. BPEC runs an equivalent course. Both expect you to be a qualified electrician first.

If an electrician on your team already does the heat pump connections, that's who takes the course. If you bring the electrical side in, the battery goes the same way.

The work is done to BS 7671 and the IET Code of Practice for Electrical Energy Storage Systems (3rd edition, 2024). Amendment 4 to BS 7671, published in April 2026, adds a chapter on stationary batteries, and Amendment 3 is withdrawn on 15 October 2026. Get the new edition on the van before then.

Fitting a battery usually means a new circuit, which is notifiable under Part P in England. You can self-certify through a competent person scheme such as NICEIC or NAPIT, use a registered third-party certifier, or notify building control directly.

Is a battery a G98 or G99 connection?

It depends on inverter size, counted across everything at the property that generates or stores electricity. Up to 16A per phase of type-tested kit (about 3.68kW on a single phase), it's G98: you connect, then notify the DNO within 28 days of commissioning. Above that it's G99, and you need the DNO's approval before you connect.

Build this into the heat pump quote. A battery with a larger inverter, or a home that already has other generation, can tip the job into G99, so apply early and put the approval in the programme. Export limitation under G100 can keep a site inside an agreed limit.

Do you need MCS certification to install batteries?

It isn't a legal requirement, and the 0% VAT doesn't depend on it. MCS does run a standard for battery work, MIS 3012 (the Battery Installation Standard, current issue MIS 3012:2025), and it's the benchmark a battery install is measured against. It requires design and installation to the IET Code of Practice and covers systems up to 50kW.

An MCS contractor adds batteries as a new technology through its certification body, and NAPIT and NICEIC both assess it. You'll need to meet the standard's competency requirements. If your heat pump work already goes through an MCS umbrella scheme, the same question applies to batteries: whose certification carries the job.

How do you become an approved installer for a battery brand?

Most brands train you before they'll let you fit or register their kit. Enphase requires certification to commission its IQ Battery, through an online course of about three hours, and reviews a new installer's first design. Fox ESS lists trained installers on its map and voids warranties that aren't registered. Tesla installs Powerwall through certified installers only.

Choose the brand as carefully as you choose the heat pump. A battery warranty runs for years, and it's worth something only while the manufacturer is trading. GivEnergy entered administration in April 2026 and is no longer honouring hardware warranties.

How big should the battery be for a heat pump home?

Size it to the heating. Most sizing advice online assumes solar, where the aim is to store the afternoon surplus for the evening. With a heat pump, the question is how much of the evening's heating you want to move into the cheap hours, and whether the battery can fill in the time the tariff gives it.

Watch inverter power as closely as capacity. A battery charging at 3kW puts about 18kWh in over six hours, so a large battery behind a small inverter may never fill overnight. The inverter rating also decides G98 or G99.

How Ample fits in

On heat pump jobs, Ample already handles the compliance: the MCS certification, the DNO notifications, a design review that leaves your design yours, and the handover pack. We're now extending the same support to batteries. See how Ample's MCS umbrella works.

Frequently asked questions

What qualifications do I need to install home batteries?
A Level 3 award in electrical energy storage systems, usually the City & Guilds 2923-34 or the BPEC equivalent. Both are aimed at qualified electricians. The work is done to BS 7671 and the IET Code of Practice for Electrical Energy Storage Systems.

Do I need MCS certification to install a battery?
It isn't a legal requirement, and the 0% VAT on battery installation doesn't depend on it. MCS runs a battery standard, MIS 3012, which an MCS contractor adds through its certification body.

Does a home battery need a G99 application?
Only if the inverters at the property total more than 16A per phase (about 3.68kW single-phase). Up to that, it's G98 and you notify the DNO within 28 days of commissioning. Above it, you need the DNO's approval before you connect.

Is there VAT on a home battery installation?
No, until 31 March 2027. The zero rate covers a battery added to existing generation and a standalone battery charged from the grid. It goes to 5% from 1 April 2027 (HMRC VAT Notice 708/6).

Can a home battery charge from the grid without solar?
Yes. A grid-charged battery fills on cheap off-peak electricity and runs the house, heat pump included, when prices are high. Check the homeowner's tariff allows battery charging in its cheap windows.

How much does a battery add to a heat pump job?
On our costings, a 5.8kWh battery installed with a heat pump adds £5,188, taking the total job from £13,150 to £18,338. Fitted as a separate job later, the same battery comes to £8,251.