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Batteries
Batteries · Fitting

How do I choose a battery installer?

Short answer

Pick an installer certified by MCS for batteries under MIS 3012, registered with a competent person scheme for electrical work, and a member of RECC or HIES. Ask how they will meet the IET Code of Practice and PAS 63100 fire rules, whether backup is included, and for insurance-backed workmanship cover. Get at least three quotes.

Last checked 24 September 2026 · 6 sources

What should I know before deciding?

MIS 3012:2025 requires design to the IET Code of Practice for EESS, CPS registration for electrical work, handover documentation, maintenance instructions and giving you the network credentials. Ask for: usable kWh and kW, warranty documents, G98/G99 plan and lead time, location assessment, backup type, commissioning into the app in your name. EST recommends at least three quotes from MCS-certified installers. Beware very short G99 lead times promised - approval can take weeks.

Does my battery installer need to be MCS certified?

It is not a legal requirement, but often matters. Octopus Flux asks for the MCS document, grant and loan schemes generally rely on certified installers, and MCS battery installers must follow MIS 3012 and the IET battery Code of Practice. Check the certificate covers batteries, not just solar.

MIS 3012 compliance mandatory for MCS:2025 contractors. Since 2024 MCS noted PAS 63100 applied indirectly via the IET CoP; BS 7671 A4 now requires it in dwellings.

How long does G99 approval take for a battery?

It depends on the route. G98 and G99 SGI-1 installs need no wait, and the fast G99 routes (SGI-2/SGI-3) give an answer within 10 working days. Full applications take longer: Ofgem's voluntary standard for distributed generation asks network operators to quote low-voltage generation connections within 45 working days (about 9 weeks), and installers often quote 6-8 weeks, sometimes 11. Ask which route a promised timeline assumes.

The 17 kW single-phase / 50 kW three-phase figure is the Form A1-1 application threshold in G99, not an automatic permission. DNOs can approve with export or generation limits.

What protection do I have if my battery installer goes out of business?

If your installer was MCS certified and a RECC or HIES member, your deposit and workmanship warranty should be insurance-backed, so an insurer pays or appoints another firm. The manufacturer's product warranty is separate and still stands if the maker trades. Ask for the insurance certificate at handover and keep it with your paperwork.

RECC: members must insure deposits and stage payments plus the workmanship warranties they issue; deposit cover 35-120+ days depending on insurer; guarantees 2, 5 or 10 years (Ark up to 12). MCS: every certified installer must buy an MCS-approved financial protection product for each customer (search summary of MCS requirements; not read in the MCS scheme document this session). Fox ESS allows a new local installer to handle claims if the original installer has gone into administration.

What to do next

Ask the installer to show the proposed location, DNO route, backup arrangement and commissioning documents before work starts.

Sources

Last checked: 24 September 2026