Solar & Battery Packages

The most important decision in a combined package is not which panel or which battery — it is whether the two are engineered as one system. Designed together, everything hangs off a single hybrid inverter: the panels feed DC in, the battery stores that DC directly, and there is one conversion to AC at the point your home actually uses the power. This is DC coupling, and it is how Lumos designs almost every solar and battery package we install.

Add a battery to an existing array later and you usually end up AC-coupled instead: a second inverter is fitted alongside the first, and every stored kilowatt-hour is converted from DC to AC, back to DC for the battery, then to AC again when you use it. Each conversion shaves off a few percent, and you have paid for two inverters to do one inverter's job. A DC-coupled battery also captures clipped generation — on bright May and June days a well-sized array can produce more than the inverter's AC output limit, and with storage on the DC side that surplus charges the battery rather than being thrown away.

The hardware we fit is built around exactly this logic. The Sigenergy SigenStor stacks its energy controller and modular battery blocks into a single DC-coupled tower, while the Tesla Powerwall 3 has a solar inverter built into the unit itself — 13.5kWh of storage that your panels wire straight into.

Designing both at once also buys you four very practical things:

• One scaffold hire and one install day — not two separate visits a year apart, each with its own access costs.
• One G99 grid application — your District Network Operator approves the inverter and export limit once, covering both technologies.
• One commissioning, one app, one point of warranty — no arguments between two manufacturers about whose kit caused a fault.
• One 0% VAT invoice — the whole package is zero-rated until 31 March 2027. Split the project into phases and a battery fitted after that date picks up VAT at 5%.

Already have panels on the roof? That is a different engineering job with its own trade-offs — our retrofit battery storage for existing solar page covers it properly. This page is about doing it right first time.

Brochures sell batteries by headline capacity. We size them from two numbers Matt Butler establishes at your free survey: how much electricity your home uses across a year, and when it uses it. A household out at work all day needs more storage relative to its array than a retired couple home at lunchtime, because more of its consumption falls after dark.

Typical sizing bands we design around

• Couples and smaller homes (roughly 2,300–2,900kWh a year): a 3.5–4.3kWp array with a 5–8kWh battery. The modular SigenStor is ideal here — a single 5kWh or 8kWh block, with room to add more if life changes.
• Family homes (roughly 3,500–4,500kWh a year): 4.3–6kWp with 10–13.5kWh of storage. A 4kWp array in our region generates around 3,900kWh a year, so the battery's job is to hold the daytime surplus for the evening surge of cooking, washing and screens.
• Larger homes with an EV or heat pump (5,500kWh and up): 6.5kWp or more with 13.5kWh-plus — a Tesla Powerwall 3, or stacked SigenStor modules where three-phase supply or future expansion matters.

The rule of thumb: the battery should comfortably cover your evening-to-morning consumption — usually 40–60% of daily use — and be fully cycled most days. An oversized battery that never empties is dead capital sitting on your garage wall.

On the roof we specify JA Solar, Trina, AIKO, Longi, SunPower and REC panels depending on roof space, budget and shading — our guide to the best solar panels in the UK explains how we choose between them. For storage, our comparison of the best home batteries in the UK for 2026 sets Sigenergy and Tesla side by side in detail.

One sizing trap worth naming: if you drive an EV, do not size the home battery to charge the car — a single charge can swallow an entire Powerwall. Instead we pair packages with EV charger installation using a myenergi Zappi, whose CT clamp diverts surplus solar straight to the car, or an Ohme with its app-based Solar Match — leaving the house battery to do the job it was sized for.

At 2026 prices — imported electricity around 27p/kWh, flat Smart Export Guarantee tariffs mostly paying between 4p and 16p, with a good, widely available rate around 10.8p — the value of a battery comes down to one figure: every kilowatt-hour you shift from export to self-use is worth roughly 16p. That is the gap between what the grid pays you and what it charges you.

A worked example

Take a working family near Melksham using 4,200kWh a year, with a 4kWp array generating about 3,900kWh:

• Solar only: out at work on weekdays, they self-use around 45% of generation. That is roughly 1,750kWh offsetting imports (about £470) plus 2,150kWh exported at 10.8p (about £230) — around £700 a year.
• Solar plus a 10kWh battery: the daytime surplus now feeds the evening instead of the grid. Self-use climbs to around 80% — roughly 3,100kWh offsetting imports (about £840) plus around £85 of export — around £925 a year, before the battery does anything else.
• The winter bonus: on a time-of-use tariff the same battery charges at cheap overnight rates and discharges through peak evening pricing, adding further savings in the months when solar alone contributes least.

That combination is how a combined package reaches — and holds — the £950–£1,100-a-year band that a solar-only system on a work-away household rarely achieves in practice. A solar-only install typically pays back in 7–9 years; adding storage raises the upfront cost, but the battery increment earns back its share comfortably inside its 10-year warranty, and the whole package keeps saving long after both paybacks pass. It also changes the risk profile: a battery-backed home buys far fewer of its units at whatever the market charges in 2030.

Export earnings still matter — around a fifth of this example's return — so registering on a decent tariff is worth doing properly; our Smart Export Guarantee explained guide covers the current rates and how MCS certification unlocks them. And for what the panels themselves cost locally before storage is added, see solar panel costs in Wiltshire.

Combined installs punish poor planning — a battery location that fails the survey, or a G99 application submitted late, can strand a project for weeks. Our process is built to land the whole system in one visit.

Survey within 5 days. We are based in Broughton Gifford, so most surveys — from solar panels in Melksham on our doorstep to solar panels in Chippenham and out across North Somerset, South Gloucestershire, Somerset and West Berkshire — happen within five days of your enquiry. Matt Butler checks the roof, the consumer unit, and crucially where the battery will live: wall strength, ventilation, temperature and cable runs all decided before anything is ordered.

Design and paperwork before install day. We model your consumption against the proposed array and battery, agree the package, and submit the G99 application to your network operator so grid approval is in hand before the scaffold goes up. As an MCS-certified, NICEIC-approved and RECC-member installer, every step is documented — no subcontracted crews, our own employed team throughout.

One day on site, most of the time. Scaffold goes up ahead of the visit; panels, hybrid inverter and battery are fitted and commissioned the same day for a typical package. Larger systems or whole-home backup configurations may need a second day, and we tell you which at quote stage, not on the morning.

Handover that unlocks your earnings. You receive your MCS certificate, electrical certification and monitoring app walkthrough within days — the MCS paperwork is what lets you register for export payments, so we do not let it drag. Then the system simply runs: the battery manages itself, and you watch it work from your phone.

Over 50 Google reviews from homeowners across our patch describe how this plays out in practice — and because we are local, the engineer who commissioned your system is the one who answers the phone afterwards.