Sigenergy Installer — Wiltshire & the South West

Lumos Energy is an MCS-certified solar and battery installer based in Broughton Gifford, just outside Melksham in Wiltshire. We install and service Sigenergy SigenStor systems as part of our wider battery storage work — surveyed, designed and fitted by our own employed team, led by our lead engineer Matt Butler, with NICEIC approval and RECC membership behind every job. One thing we won't claim: we are not a "certified Sigenergy partner", because that isn't a badge we can verify. We're an independent MCS installer that fits and services Sigenergy equipment — this page sets out exactly what we install, where, and what it costs.

What we install

SigenStor is a modular stacked system: a hybrid inverter unit with LiFePO4 battery modules that clip together into a single tower. The UK modules come in two sizes — 5.38 kWh and 8.06 kWh nominal (roughly 5.2 kWh and 7.8 kWh usable) — and you can stack one to six modules per tower, giving around 5 to 48 kWh of storage from one footprint. Round-trip efficiency is quoted at 93–95%. There's also an optional DC EV-charging module that slots into the same stack, so the car charges from the same DC bus as your panels and battery rather than through an extra conversion step. Where Sigenergy isn't the right fit, we also install Tesla Powerwall 3.

Why we rate Sigenergy — honestly

Three things stand out from fitting and monitoring these systems. First, modularity: you can start with a single module and add capacity later when a heat pump or EV arrives, without replacing the inverter. Second, EV integration: the DC charging module is a genuinely different architecture from bolting a separate AC charger on the wall. Third, firmware cadence: Sigenergy ships over-the-air updates frequently, and the app has visibly improved since we started fitting the system. The honest flip side: fast-moving firmware means the app changes often, and the EV DC module carries a shorter 3-year warranty than the batteries. Our full verdict, including what we'd change, is in our battery review.

Where we install (read this before you enquire)

We install within roughly 30 miles of Melksham. In practice that means west and north Wiltshire — Melksham, Chippenham, Trowbridge, Bradford-on-Avon, Corsham, Calne, Devizes, Marlborough, Swindon — plus Bath and North East Somerset, North Somerset, South Gloucestershire, West Berkshire and much of Somerset. Salisbury sits right on the edge of that band: ask, and we'll be straight about whether we can look after you properly. If you're further afield, we're not the right installer for ongoing service, and pretending otherwise helps nobody — use the installer search on the Sigenergy website (sigenergy.com) to find someone genuinely local. If you're nearby and also weighing up panels, start with our solar panels in Melksham page.

How the install works

• Survey — free, booked within five days. We check your consumer unit, existing solar (if any), usage pattern and where the stack will live.
• Design — we size the stack in whole modules against your actual consumption, not a one-size quote, and give you a fixed price.
• Install — our own engineers, not subcontractors. We handle the DNO notification.
• Handover — app setup, commissioning certificates, MCS paperwork and warranty registration before we leave.

Sigenergy installation FAQs

What does a Sigenergy system cost per kWh installed? It depends on stack size, because the hybrid inverter base is a fixed cost — so cost per kWh falls sharply as you add modules. Most Sigenergy systems we quote land between £5,000 and £14,000 installed: a single-module retrofit sits at the bottom of that band, a large multi-module stack with the EV module towards the top. Domestic solar and battery installations are 0% VAT until 31 March 2027, and our prices already reflect that.

Can you retrofit SigenStor to my existing solar panels? Yes. Depending on the age and warranty position of your current inverter, we either couple the SigenStor alongside it or move your panels onto the Sigen hybrid. See retrofitting battery storage to existing solar for how we decide.

How does the warranty work? Sigenergy's European warranty gives 10 years on the battery modules, the Energy Controller and the battery connector — guaranteeing 70% capacity retention or a minimum energy throughput (15.84 MWh on the 5 kWh-class module, 23.77 MWh on the 8 kWh) — with 5 years on the Sigen Gateway and 3 years on the EV DC charging module. After GivEnergy entered administration in April 2026, "who stands behind the warranty" is a fair question to ask of any brand; ask us and we'll give you a straight view.

How long does installation take? A battery-only retrofit is normally one working day. Solar plus a SigenStor stack is typically two. Commissioning paperwork and warranty registration follow within days, not months.