Can a portable power station run your fridge-freezer through a 24-hour power cut?

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Yes, a portable power station can keep a fridge-freezer running through a 24-hour power cut, as long as it's big enough. The size you need comes straight from the energy label. Here's how to work it out, with the sums shown.

How do I work out what size power station my fridge needs?

You need three numbers.

1. Daily use from the label. UK labelling rules say a fridge's energy label shows its annual energy use in kWh/annum (legislation.gov.uk, Annex III). That figure is the average daily use multiplied by 365 (Annex I). So:

Wh per day = kWh/annum ÷ 365 x 1,000

2. Hours you want to cover. 12 hours (overnight) or 24 hours.

3. An allowance for losses. A power station loses some energy turning its battery power into mains power. Jackery's UK guide works out running time as capacity x 0.85 ÷ the device's watts (Jackery UK). Another Jackery guide explains the 0.85 as allowing for a 15% loss of power while working (Jackery).

Turn that round and you get:

Power station Wh needed = Wh per day x (hours ÷ 24) ÷ 0.85

Sizing table: 12 and 24 hours

These are example label figures to show the working, not claims about any model. Use your own label.

Worked example for 250 kWh a year: 250 ÷ 365 = 0.685 kWh = 685 Wh a day. For 24 hours, 685 ÷ 0.85 = 806 Wh. For 12 hours, half of 685 is 342, and 342 ÷ 0.85 = 403 Wh.

Add some headroom on top. The label comes from a standard test, and a fridge in a warm kitchen that's opened a lot will use more. Jackery's UK guide notes the compressor works harder when the room is warmer.

How long will my power station run the fridge?

Flip the sum round. Your fridge's average draw in watts is its Wh per day ÷ 24. Then use Jackery's rule: capacity x 0.85 ÷ watts.

For a label figure of 250 kWh a year, the average draw is 685 ÷ 24 = about 28.5 W. So:

Why use the average, not the wattage on the rating plate? A fridge's compressor switches on and off. The label figure is the total over a day, so it already includes the time it's off. Jackery's own examples divide by a fridge's running wattage of several hundred watts. That treats the fridge as if it runs non-stop, so it gives a much shorter, more cautious time. If you want a cautious answer, use the label figure and add headroom.

Our power station runtime calculator does this for any device.

What about the start-up surge?

When a fridge's compressor kicks in, it needs a short burst of extra power. Jackery's UK guide says the power station must be able to handle that start-up "surge", and that standard portable solar panels on their own can't provide it (Jackery UK). Another Jackery guide says a fridge's starting wattage is always higher than its running wattage, for a few seconds (Jackery).

So check two numbers on any power station:

• Capacity (Wh): how long it lasts. Use the table above.
• Output and surge (W): whether it can start the compressor. Check the fridge maker's manual or ask them what start-up power it needs.

Do I need to power the fridge at all?

For short cuts, often not. The Food Standards Agency says (FSA on GOV.UK):

• Keep fridge and freezer doors closed as much as possible.
• A fridge should stay cold for up to 4 hours.
• Food should stay frozen for up to 48 hours in a full freezer, or 24 hours if half full. These are estimates and vary by model.
• Use a fridge thermometer. Fridges should normally be at 5°C or below.
• In a power cut, food can stay in a fridge that's under 8°C.
• If it reaches 8°C or above, eat chilled food within 4 hours or throw it away, unless the power comes back in that time.
• Cuts under 4 hours are unlikely to affect chilled or frozen food.

GOV.UK Be Ready also says keeping the doors closed will keep them cold for several hours (Be Ready). Our fridge-freezer power cut timer helps you track this.

A sensible plan for many homes:

1. Keep the doors shut for the first few hours.
2. If the cut drags on, run the freezer or fridge-freezer from the power station in blocks, and check the thermometer.
3. Save the power station for what matters most: medicines that must stay cold, then food. See medicines that need a fridge in a power cut.

Can solar panels keep it going for longer?

Solar can top up a power station during the day. Jackery's UK guide says the panels on their own can't start a compressor, so they charge the power station and the power station runs the fridge. How much a panel gives you depends on the season and the weather. See portable solar panels in a UK winter.

More on power cuts and fridges

• How much electricity does a fridge-freezer use a day? (with costs at the price cap)
• What size power station for a UK power cut?
• Fridge and freezer in a power cut
• Power stations for power cuts

Limitations

This is general information, not professional advice. Label figures come from a standard test, and real use varies with room temperature, how full the fridge is and how often it's opened. Check your fridge and power station manuals before connecting them. Follow FSA advice on food safety, and call 999 in an emergency.

Related guides

• Fridge and freezer in a power cut: how long is food safe?
• Do you need a portable power station for power cuts?
• Medicines that need a fridge: what to do in a power cut
• Power cut kit: what to keep in one box, and how long power cuts last

Free tools

• Power station runtime calculator
• Fridge and freezer power cut timer

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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