A home battery without solar panels, honestly assessed

The short answer

A battery with no solar panels does earn money, every night of the year. You buy electricity at an off peak rate of around 8p per kWh overnight and use it when the standard rate is 26.11p. After round trip losses that is about 17.2p saved on every usable unit the battery delivers, and none of it depends on the weather.

Whether it is worth buying comes down to one thing: how many units you can genuinely push through it. That is where most of the optimism goes. A battery moves electricity in time. It never reduces how much you buy, and it earns nothing on a night you do not fill it or a day you do not empty it.

What a battery on its own actually earns

Start with the spread. Charging at 8p and losing about 10% on the round trip means a unit delivered into the house cost 8.9p to buy. Against the 26.11p Ofgem cap average for 1 July to 30 September 2026, that is 17.2p saved. Multiply it by usable capacity, then by the number of days you truly empty the pack.

Saving of 17.2p per usable kWh: charged at 8p, round trip losses taken at 10%, measured against the 26.11p Ofgem cap average for 1 July to 30 September 2026. Installed prices are published market ranges for standalone battery installations, not OVO quotes. Three hundred full cycles a year assumes a household that genuinely empties the pack on five days in six. Payback is simple, with no allowance for tariff changes or the cost of money.

The middle row is the interesting one. A large share of the price of any battery installation is the visit, the inverter, the electrical work and the paperwork, and none of that shrinks when the pack does, so buying about 10 kWh rather than about 5.8 kWh costs a few hundred pounds more and roughly doubles what the battery can earn, provided you can empty it. The small pack looks cheap and pays back slowest. Two things the table does not flatter either: your standing charge does not move, so the 57.19p a day stays exactly where it was, and cheap overnight rates are normally paid for with a dearer daytime rate, so a household that uses a lot between breakfast and teatime hands some of the gain straight back.

What you give up by leaving the panels off

• Generation you never paid for. Every unit still comes off the grid. A battery changes when you buy, not whether you buy. Solar is the only part of the system that makes electricity you were never billed for.
• Export income. Electricity you bought from the grid and pushed back out sits outside the Smart Export Guarantee obligation, so a supplier is not required to pay for it and the terms differ from one tariff to the next. With no generation, there is nothing to sell that reliably earns. Our guide to how the Smart Export Guarantee works sets out what qualifies.
• The 20p rate. Where OVO fits both the solar and the battery, you take your electricity supply from OVO and the system is under 30kW, the SEG Install Exclusive rate is 20p per kWh. It is conditioned on the panels being there, and it is one of the highest rates available anywhere in the market.
• The cheapest electricity there is. Between April and September a well filled roof covers a large part of a typical home's daytime use outright. That is a saving no tariff can match, because the unit cost nothing to produce. The month by month working is on the strategy page.

Who it suits, and who it does not

• No usable roof. A flat, a north facing pitch with nothing else to work with, or a roof shaded enough that an array would spend the day going in and out of cover.
• Planning gets in the way. Listed buildings and parts of some conservation areas turn panels into a fight that a battery in the garage or the utility room simply does not start.
• The roof is due for replacement. Fitting panels to a covering with a few years left in it means paying to take them off and put them back. A battery now and panels when the roof is done is a sensible order.
• You use a lot after dark. Electric heating, a cylinder on a timer, a home office running late. The more of your day sits outside the cheap window, the more units the battery has to work with.

The cases where it does not work are just as clear, and they are worth being blunt about before anybody spends four thousand pounds.

• Low users. A household on about 1,600 kWh a year gets through roughly 4.4 kWh a day in total, cheap window included. There is not enough left over to fill even a small pack most nights, and the payback stretches out past the warranty.
• No smart meter, and no prospect of one. Time of use pricing depends on half hourly readings. Without a working smart meter no supplier can bill you at an off peak rate, and the whole case collapses.
• Anyone who will not change tariff. On a flat rate there is no cheap window to charge in. The battery becomes an expensive way of losing about 10% of everything that passes through it.

Before you commit

One more point about warranties, learned the hard way by British homeowners this year. A warranty is only worth as much as the company standing behind it, and the collapse of a well known domestic battery brand in April 2026 left a lot of people holding paperwork with nobody to honour it. The hardware carried on working, but the promise behind it did not. Ask who carries the workmanship cover as well as the product cover, and get both in writing. Every installation we do carries the OVO guaranteed 10 year workmanship warranty.

Rates quoted here are correct as at 4 August 2026. Ofgem publishes the cap for 1 October to 31 December 2026 by 26 August 2026, and off peak tariffs move more often than that. We rerun the arithmetic on your actual tariff on the design call.