A battery with no panels sounds odd. It is a storage device with nothing generating anything to store.
It works because of when electricity costs what it costs. This is a growing and perfectly sensible option, and almost no solar site explains it because it does not involve selling panels.
How it makes money
On a time-of-use tariff, electricity is much cheaper overnight than during the evening peak. A battery charges in the cheap window and runs the house through the expensive one.
You are not generating anything. You are buying electricity at one price and using it instead of buying it at a higher price. The difference between the two prices, minus a small loss in the charging and discharging, is the saving.
Unlike solar, this works:
- Every night of the year, regardless of weather
- In December as well as June
- On a north-facing roof, or no roof at all
- On a flat, a terrace, or a listed building where panels are not permitted
See smart tariffs for how time-of-use pricing works.
What it costs
Around £3,500 to £5,500 for roughly 4 to 5kWh of storage, plus installation.
VAT on an installed battery is currently 0% until 31 Mar 2027, and a battery qualifies on its own. You do not need to fit solar at the same time to get the relief. A lot of older guidance says otherwise and is wrong.
Prices are indicative ranges, last reviewed 6 Nov 2026.
Working out whether it stacks up
Straightforward arithmetic, and worth doing before anyone quotes you:
- Find the price difference between the cheap overnight rate and the rate you would otherwise pay in the evening on your chosen tariff.
- Work out how many kWh you would shift each day. That is limited by the usable capacity of the battery and by how much you actually use during the expensive period.
- Multiply, then multiply by 365.
- Divide the installed cost by that figure.
Two things to be careful about:
- Usable capacity is lower than headline capacity. Use the usable figure.
- You only save on electricity you would have bought anyway. A battery bigger than your evening use does not earn on the extra capacity.
When this beats fitting solar first
- You have no suitable roof. Shaded, too small, wrong direction, a flat, a listed building, or a conservation area refusal.
- You rent, though check with the landlord, because it is a fixed installation.
- Your roof needs replacing soon. Battery now, panels when the roof is done.
- Budget only stretches to one thing and most of your electricity use is in the evening.
When solar first is the better move
- You have a decent unshaded roof and daytime electricity use.
- You want to reduce total consumption from the grid rather than just shift when you buy it.
- You want export income. A battery with no generation has nothing of its own to sell, though on some tariffs you can export stored electricity at peak rates, which is a different arrangement worth asking about.
The risk to understand
The saving depends entirely on a tariff continuing to have a large gap between cheap and expensive periods. Tariffs change, sometimes at short notice.
The underlying reason for time-of-use pricing is not going away: the grid needs demand to move away from peak periods and pricing is how it does that. But the specific size of the gap is not guaranteed. Treat the payback calculation as an estimate based on current tariffs, not a fixed return.
What to ask
- Usable capacity in kWh, and power output in kW
- Can it charge from the grid on a schedule, automatically?
- Who configures it, and what happens if I change tariff?
- Where will it go, and how does that comply with the siting rules?
- Can it be extended if I fit solar later?
- Will the inverter support panels later, or will it need replacing?
That last one matters. If solar is a possibility down the line, a hybrid inverter now saves money later. See hybrid systems.