Solar + Battery (New Combined Install): Home battery storage

Solar and battery together: the cheapest way to get both, and the strongest fit for a home with no panels yet

If your roof is bare and you want to cut your electricity bill for the next 15 to 20 years, fitting solar panels and a battery at the same time is almost always the sensible move. The reason is simple: the expensive, disruptive parts of the job, the scaffolding, the roof labour, the inverter and the electrical work, are all paid for once and shared across both the panels and the battery. Add a battery to solar later and you pay for a second visit and often a second inverter. Do it together and you get a single MCS install, a single notification to your network operator, and a single invoice with 0 percent VAT on the whole lot. For most homeowners without existing solar, that combined system is the default recommendation.

The idea is straightforward. Your panels generate most of their power in the middle of the day, which is exactly when most households use the least. Without a battery you export that midday surplus to the grid for around 12 to 15p a unit, then buy it back in the evening at 28p or more. A battery stores your own daytime generation so you use it after dark instead of paying the grid twice over. In practice this lifts the share of your solar you actually use, your self-consumption, from a typical 40 percent up towards 80 percent and beyond. That shift is where the real saving lives.

Who it suits

This is the right choice for an owner-occupier in a 3 or 4 bed house with a south, east or west facing roof that gets reasonable daylight, and no panels yet. It suits families whose heavy usage is in the evening, and anyone who wants to hedge against future price rises rather than chase a fast payback. If you already have solar, you do not need a fresh array; see our battery-only retrofit page instead. If your roof genuinely cannot take panels, a battery without solar on a cheap overnight tariff may be the better route.

How it works, and why coupling matters

Because the panels and battery go in together, they are usually DC-coupled, sharing one hybrid inverter. DC coupling is the more efficient arrangement, with a round-trip efficiency of roughly 95 to 97 percent, meaning very little of your solar is lost in the storing and releasing. A retrofit battery bolted onto an older solar system is normally AC-coupled with its own inverter, which is slightly less efficient at around 90 to 92 percent. Getting DC coupling on a new combined install is one of the quiet advantages of doing both at once.

One point worth understanding early: the number that matters is usable capacity in kilowatt-hours, not the headline nominal figure a brochure prints. Modern lithium-iron-phosphate (LFP) batteries give you 90 to 100 percent of their nominal capacity as usable, but always compare quotes on usable kWh or you are comparing different sized batteries.

Realistic cost and payback

A full solar-and-battery system in the UK in 2026 typically runs £9,000 to £16,000 including 0 percent VAT, covering roughly 8 to 14 panels (a 3.5 to 5.5 kWp array) and a 5 to 13.5 kWh usable battery. As a rule of thumb, the battery portion works out at around £500 to £800 per usable kWh installed. Payback on a combined new system generally lands between 6 and 10 years, with a typical figure near 8 years, and the panels then keep generating well beyond that. A 10 kWh battery cycling once a day tends to save in the region of £550 to £620 a year, on top of the direct saving from using your own solar rather than buying grid power.

Do not judge this purely on the battery's own payback. The array is generating free electricity for two decades, and the battery simply stops you giving that electricity away cheaply and buying it back dear. We will always model the honest number against your actual annual usage rather than quote a headline saving, and if the sums do not stack up for your home we will say so.

Getting the size right

Size the battery to the daytime surplus you would otherwise export, not to your panel wattage. A typical 3,000 to 4,500 kWh a year household lands on about a 10 kWh battery, the sweet spot most homes choose. Lower usage under roughly 2,800 kWh a year suits a 5 kWh battery, while high-usage homes, EV owners or heat-pump households step up to 13.5 kWh or more. A battery too big to fill every day is just capital you never earn back. Our savings calculator gives you a first estimate from your annual usage.

0 percent VAT while it lasts

Domestic battery storage and solar both attract 0 percent VAT in Great Britain until 31 March 2027, after which the rate reverts to 5 percent (not the old 20 percent). On a combined system that relief is worth well over a thousand pounds, and it is one of the strongest reasons to install before the deadline. Our cost guide and grants and funding page walk through the VAT position and the Smart Export Guarantee, which pays you for any true surplus you still export.

Key considerations

• Coupling: DC-coupled for a new combined install (95 to 97 percent efficient), which is a benefit of doing both together.
• DNO notification: your installer notifies the network operator under G98 for systems up to 3.68 kW per phase, or applies under G99 above that. No action needed from you beyond signing off.
• Planning: a domestic solar-and-battery system is permitted development, so no planning permission for almost all homes. Listed buildings and conservation areas can have siting considerations.
• Safety and warranty: insist on LFP chemistry, which is far more thermally stable than older lithium types, installed to BS 7671 and the PAS 63100 fire-safety code by an MCS-registered, RECC-backed installer. Quality LFP is typically warranted for 6,000 to 10,000 cycles or 10 to 12 years to around 70 to 80 percent capacity.
• Manufacturer stability: a battery is only as good as the company standing behind its warranty. GivEnergy, a major UK residential battery maker, entered administration in April 2026, which put ongoing warranty support, firmware and spares in serious doubt for its systems. We would not recommend buying a new GivEnergy system today, and we factor manufacturer stability into every brand steer. We compare independent installers, so you get an honest recommendation rather than whichever brand an installer is tied to.

An illustrative example

As an illustrative composite, not a named customer: a family in a 4-bed detached with a bare south-facing roof used about 4,300 kWh a year, most of it in the evening. They fitted a 4.8 kWp array (12 panels) with a 10 kWh usable LFP battery, DC-coupled, for around £13,500 including 0 percent VAT. In the model their solar self-consumption rose from what would have been roughly 40 percent to about 82 percent, evening grid imports fell sharply, and combined with a small Smart Export Guarantee income the yearly saving came out near £900 to £1,100, giving a payback around 8 years with two decades of generation still ahead. These figures are illustrative and depend on your roof, usage and tariff.

When you are ready, read the cost guide, check what you could save with the savings calculator, or get an honest quote from MCS-registered installers. If you are still weighing options, the FAQs answer the common questions, and you can compare this with a 10 kWh system or a larger 13.5 kWh setup.