Tesla Powerwall Installer — Wiltshire & the South West

Lumos Energy installs and services the Tesla Powerwall 3 across Wiltshire and the surrounding South West. Every job is surveyed, designed, DNO-notified and commissioned by our own employed team, led by lead engineer Matt Butler, from our base in Broughton Gifford, near Melksham. We are MCS certified, NICEIC approved and RECC members, and we fit Powerwall both as part of new solar installations and as an addition to our wider battery storage work. Book a free survey and we will be with you within five days.

Powerwall 3, as we install it

The Powerwall 3 is a single 13.5 kWh home battery with a solar inverter built into the unit itself. That integrated inverter is the headline feature: on a new solar-plus-battery installation the Powerwall is the inverter — your panels wire straight into its own MPPT inputs, so there is no separate hybrid inverter to buy, mount or maintain. That is why we usually quote it alongside a new array on our solar and battery installations.

Usable capacity	13.5 kWh
Continuous output	Up to 11.04 kW on-grid
Inverter	Integrated solar inverter (DC-coupled) — replaces a separate hybrid inverter on new installs
Backup	Whole-home backup capability with the Backup Gateway
Chemistry	LFP (lithium iron phosphate)
Warranty	10 years to 70% retained capacity — no cycle cap for solar self-consumption

Powerwall 3 or a modular battery?

We fit two battery systems, and we will tell you straight which suits your house. The Powerwall 3 is one fixed 13.5 kWh block; the Sigenergy SigenStor stacks 5.38 kWh or 8.06 kWh modules into whatever capacity you actually need. Powerwall tends to win for higher-usage homes that will genuinely cycle 13.5 kWh, for whole-home backup in a single unit, and on new solar installs where its built-in inverter saves you buying one. SigenStor tends to win when 13.5 kWh is more than you need on day one, when you want to add capacity later without a second large unit, or when the stack-and-expand layout suits the space better. Both routes are covered in detail on our Sigenergy installer hub.

Where we install — and where we don't

We work within roughly 30 miles of Melksham: Wiltshire, Bath and North East Somerset, North Somerset, South Gloucestershire, West Berkshire and much of Somerset. That radius is deliberate — it keeps surveys, install days and any after-care visits genuinely local. If you are outside that band, the honest answer is that a closer firm will serve you better, and Tesla's own Find an Installer tool on tesla.com will list companies in your area.

The install process — including the DNO paperwork

After the free survey we design the system, handle the grid paperwork, then install — typically a single day on site — before commissioning, registering the system and handing over your certificates. One point worth being honest about: small systems up to 16 A per phase (3.68 kW) can connect first and notify the network operator afterwards under G98, but the Powerwall 3's 11.04 kW output is well above that line, so most installations need a G99 application approved by your DNO before we install. We prepare and submit that application for you; it adds some lead time up front (it varies by network operator), but it is the compliant route and it protects your right to export.

Tesla Powerwall questions, answered

How much does a Powerwall 3 cost installed? In 2026, a straightforward single-unit installation in the UK typically lands between £8,000 and £10,500 fully installed, depending on whether it is fitted with new solar or as a retrofit, cable runs and the unit's location. Domestic battery storage currently carries 0% VAT until 31 March 2027, which is already reflected in those figures — and with the price cap rising to 26.32p/kWh from 1 October, shifting 13.5 kWh of usage a day does meaningful work.

Can it be retrofitted to my existing solar panels? Yes. The Powerwall 3 is a DC-coupled battery with its own inverter, and there are two retrofit routes: AC-couple it alongside your existing solar inverter, which stays in place and keeps working as before, or — where it makes sense — move your panels onto the Powerwall's own MPPT inputs and retire an ageing inverter entirely. We will recommend the right route at survey; see our retrofit battery storage page for how we assess it.

How long does installation take? Once DNO approval is in place, most installations are completed in a single day on site. Retrofits that re-wire panels onto the Powerwall's own inputs can run longer, which we will flag at quote stage.

What does the warranty actually cover? Ten years, with a guarantee of at least 70% of original capacity at the end of it — and because the inverter is part of the unit, it sits inside the same 10-year cover. For solar self-consumption use there is no cycle or throughput cap on that guarantee. To be clear about our role: we install and service Tesla Powerwall as an independent MCS-certified installer, and your workmanship guarantee sits with us alongside Tesla's product warranty.