Solar generators for UK home back-up: do they work in winter?

What a "solar generator" really is

It's two things sold together:

1. A portable power station: a large rechargeable battery in a box, with normal 3-pin sockets, USB ports and a screen.
2. A folding solar panel that plugs into it.

There's no engine and no fuel. The name "generator" is marketing. You can charge the battery from a wall socket, a car, or the panel, then run things from it during a power cut.

Does it work in a UK winter?

It works, but the panel adds much less than the box suggests.

The Met Office keeps records of bright sunshine across the UK every month. Our averages from its data for 1991–2020:

That's the whole month, not per day. In December the UK averages less than 1.5 hours of bright sun a day.

On cloudy days a panel still produces some power, but far less than its rated watts. Our post on portable solar panels in a UK winter has modelled figures for a 100 W panel in London, Manchester and Edinburgh, and shows how much the angle matters.

The practical answer: in winter, charge the battery from the mains when a storm is forecast, and use the panel as a small top-up during a long cut. From spring to autumn the panel does much more.

What can it run?

That depends on the battery size (watt-hours, Wh) and the socket's output (watts, W). Very roughly:

• Small (about 250–300 Wh): phones, lights, a router and a laptop for a day or more.
• Medium (about 500 Wh): the above, plus a fridge for some hours.
• Large (about 1,000 Wh): a fridge or freezer cycling on and off for longer, or a CPAP machine overnight.

These are the sizes and uses listed in our 1 November buy list, not tests. Our power station sizing post and runtime calculator let you check your own appliances.

It won't run: an electric heater, kettle, oven or electric shower for long. They use too much power.

The freezer question

People often buy a solar generator to save a freezer. You may not need to.

The Food Standards Agency says a full freezer should stay frozen for up to 48 hours (24 hours if half full), and a fridge should stay cold for up to 4 hours, as long as you keep the doors shut. Most power cuts are much shorter than that.

To check whether a battery could run your freezer:

1. Find the kWh per year on its energy label.
2. Divide by 365 to get kWh per day, then multiply by 1,000 for watt-hours.
3. Compare that with the battery's Wh. A battery smaller than one day's use won't get you through a full day, and a winter panel won't refill it.

Example only: a freezer labelled 200 kWh a year uses about 550 Wh a day. Check your own label.

Can you use it indoors?

The battery unit, yes. It burns no fuel, so it gives off no carbon monoxide. That's the big difference from a petrol or diesel generator, which the NHS lists as a source of carbon monoxide and which must only ever run outdoors. Our generator safety post covers petrol generators.

Safe charging: Electrical Safety First's advice for battery packs applies here:

• buy from a known brand or a reputable shop, not an unknown third-party seller;
• charge it uncovered, somewhere ventilated, away from heat;
• don't charge it overnight or while you're out;
• stop using it if it smells odd, sparks, smokes, swells or cracks.

The panel goes outside, tilted towards the south and out of shade.

What does it cost?

Prices we found on 1 November 2026 (they change often):

• Power station: about £219 for a small 300 Wh-class unit, £449 for a 512 Wh unit, and £469–£599 for 1,000 Wh-class units.
• 100 W folding panel: about £100–£120.

So a small "solar generator" kit costs roughly £320 or more, and a large one £570–£720.

Charging from the mains is cheap. Ofgem's price cap rate for electricity from 1 October 2026 averages 26.32p per kWh (Direct Debit, before standing charge). A full charge of a 512 Wh battery uses about half a kWh from the wall, so roughly 13–15p, allowing a little for charging losses. The panel saves pennies; its value is that it works when the mains doesn't.

Is it worth it for you?

Probably yes if: - someone relies on powered medical equipment (also join the Priority Services Register); - you work from home and need a laptop and router through a cut; - you live somewhere with long or frequent power cuts.

Probably not yet if: - you don't have the basics. Be Ready's power cut advice is about torches, a radio, a charged power bank and keeping warm, not power stations; - your power cuts are usually a few hours. A good power bank does most of the job.

What we couldn't check

• The Energy Saving Trust's pages blocked our checks, so we haven't cited it.
• The capacity guide above is general, from product specifications on our buy list, not our own tests.
• We don't test or rank solar generator brands.

Related guides

• Do you need a portable power station for power cuts?
• Power cut kit: what to keep in one box, and how long power cuts last
• How many phone charges will a power bank give you in a power cut?
• Will there be blackouts this winter? What the 2026/27 outlook says

Free tools

• Power bank and power station runtime calculator
• Fridge and freezer power cut timer (FSA times)

We're an independent UK site, not the government. We check guides against official sources and link to them. In an emergency call 999.

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