If you only read one page on this site before getting quotes, make it this one.
The biggest change to UK home solar in the last decade is not a panel or a battery. It is the tariff. Time-of-use electricity pricing has quietly become the thing that decides whether a battery is worth buying, and most solar advice still does not mention it.
The old picture
Until recently, a household on a standard tariff paid roughly the same price for electricity all day. Solar made sense if you used what you generated, and exports earned you a flat rate from your supplier.
That still works. It is just no longer the best version available.
What a time-of-use tariff does
A time-of-use tariff charges different prices at different times of day. Typically:
- An overnight window, often something like 23:30 to 05:30, priced very low, in the region of 6.5p per unit
- A peak period, usually early evening, priced high
- The rest of the day somewhere in between
The equivalent exists for export. A time-of-use export tariff pays a much higher rate during a peak window, sometimes around 16p, and very little outside it.
Rates here illustrate the structure. They are not current quotes and they change frequently. Last reviewed 4 Nov 2026. Always check the supplier’s own published terms.
Why this changes everything for a battery
On a flat tariff, a battery does one job: it stores your solar so you use it in the evening instead of exporting it at about half value. Useful, but it only works when the sun has been out.
On a time-of-use tariff, a battery does three jobs:
- Stores your solar, as before.
- Charges overnight at the cheap rate and runs the house through the expensive evening peak. This works in December when the panels produce almost nothing.
- Exports during the peak window on an export tariff that pays properly for it.
The second point is the one people miss. A battery on a time-of-use tariff earns its keep every single night of the year, regardless of weather. That is a completely different proposition from a battery that only works on sunny days.
Why solar exports are worth less than you would hope
Solar produces most in the middle of the day. That is also when electricity is cheapest and most plentiful on the grid, which is exactly why flat export rates are low relative to what you pay to import.
A battery lets you hold that generation back until the evening, when it is worth considerably more. You are not generating any more electricity. You are selling it at a better time.
A watch-out on headline export rates
When you see an export rate advertised at 27p or 30p, check what kind of tariff it is before getting excited.
- A flat export rate pays the same whenever you export. These currently sit around 12p to 13p per kWh.
- A time-of-use export rate pays its headline figure only in a peak window, and much less the rest of the time. Without a battery you will export almost nothing during that window, so the headline rate is close to meaningless.
Neither is better in the abstract. A flat rate suits solar with no battery. A time-of-use rate suits solar with a battery. Matching the tariff to the system is the decision.
Import and export can be with different suppliers
Under the Smart Export Guarantee, import and export are legally separate. You can buy from one supplier and sell to another.
In practice most of the better flat rates are only offered to customers who also buy their electricity from that supplier, so your real choice is narrower. Still worth knowing, because it means you are never locked in to your current supplier’s export offer. See export payments.
If you have an electric car
Electric vehicle tariffs give a cheap overnight window aimed at charging the car. Suppliers have started allowing an EV import tariff to be paired with a proper export tariff, which previously was not possible.
That combination is strong: cheap overnight electricity for the car and the battery, solar covering the daytime, and a decent export rate for the surplus. See charging an electric car from solar.
What to check before you commit
- Does the battery support scheduled charging? It needs to be able to charge from the grid in a set window, automatically. Not all setups do this well.
- Does the installer set it up, or do you? Ask. A battery on the wrong settings quietly earns nothing.
- Is there a smart meter? Time-of-use tariffs require one that reads half-hourly.
- What are the exit terms? Tariffs change. Do not sign up to something you cannot leave.
- Does the export tariff require you to import from the same supplier? Usually yes for the better rates.
An honest caveat
Tariffs change often, sometimes at short notice. A battery bought purely on today’s tariff rates is a bet that something like them will still be available in five years. That is a reasonable bet, because the underlying reason for time-of-use pricing is not going away, but it is a bet rather than a certainty. Size the purchase accordingly.