Power cut guide
Choosing a Portable Power Station for Power Cuts
Quick answer: Look at two numbers: watt-hours (Wh), which tell you how much energy the battery stores, and watts (W), which tell you how much power it can deliver at once. Add up the watts of what you want to run, check the power station’s output rating is comfortably higher, then divide the usable watt-hours by that total to estimate the hours. For most homes, a unit with a pure sine wave output, a LiFePO4 battery and enough capacity for phones, lights, Wi-Fi and perhaps a fridge in short bursts is a sensible starting point.
Is the power off where you are? See live power cuts from the network operators and reports from neighbours.
A portable power station is a large rechargeable battery with built-in sockets, USB ports and sometimes 12V outlets. Unlike a generator it is silent, produces no fumes and can be used safely indoors. This guide explains how to read the specifications, estimate how long one will last, and decide what size you actually need, without recommending any brand.
What a portable power station can and cannot do
Power stations are good at keeping small, important things going: phones, a router, LED lamps, a laptop, a radio, a CPAP machine or a small TV. Larger units can run a fridge or freezer for a while, though not for days.
They are not a whole-house backup. They do not connect to your home wiring, and they will not run heating, an electric shower or an oven for any useful length of time. If you need to power more for longer, compare them with the options in our guide to home generators for power cuts. A fixed home battery is another option, covered in solar panels and home batteries in a power cut.
A power station sits within a wider plan. Our power cut emergency kit checklist covers the torches, radio, water and warm layers that matter just as much.
Watts vs watt-hours: the two numbers that matter
These two figures are often confused, and getting them right is most of the work.
| Term | What it measures | Think of it as | Where to find it |
|---|---|---|---|
| Watt-hours (Wh) | How much energy the battery holds | The size of the fuel tank | Usually in the product name or spec sheet |
| Rated output (W) | The most power it can supply continuously | How fast it can pour | “AC output” or “rated power” |
| Surge or peak (W) | A brief burst for appliances that need a kick to start | A short sprint | “Surge” or “peak power” |
| Appliance watts (W) | What each device draws while running | How thirsty it is | The rating plate or power adapter label |
The rule is simple. The total watts of everything you plug in at once must stay below the power station’s rated output. The watt-hours decide how long it can keep that up.
If a label gives volts and amps rather than watts, multiply them: a 12V adapter rated at 1.5A can draw up to 18W. Labels show the maximum, so real use is often lower.
How to estimate runtime: a worked example
Say your power goes off at 7pm on a winter evening and you want to keep the following running until the morning. These figures are examples only, so check the labels on your own devices.
| Device | Watts (example) | Hours needed | Watt-hours |
|---|---|---|---|
| Broadband router | 12 W | 12 | 144 Wh |
| Two LED lamps | 2 x 8 W | 5 | 80 Wh |
| Charging two phones | about 15 Wh each | – | 30 Wh |
| Laptop | 45 W | 3 | 135 Wh |
| Total | Peak about 73 W at once | 389 Wh |
Power stations never deliver all their rated watt-hours. Some energy is lost turning battery power into mains-style AC, and many units stop before the battery is fully empty to protect it. For planning, a cautious assumption is that you will get about 80% of the rated capacity from the AC sockets. USB and 12V outputs usually waste less.
- Total energy needed: 389 Wh.
- Divide by 0.8 to allow for losses: 389 ÷ 0.8 = about 486 Wh.
- Choose a unit rated comfortably above that, for example 600 Wh or more, so you are not running it flat.
- Check the rated output: the 73 W peak is well within almost any unit’s limit.
To work out runtime the other way round, take the rated Wh, multiply by 0.8, and divide by the watts you are drawing. A 1,000 Wh unit running a 12 W router alone would last roughly 1,000 x 0.8 ÷ 12, or about 66 hours, in theory. Our battery backup calculator does these sums for you.
What about a fridge or freezer?
Fridges and freezers do not run constantly. The compressor switches on and off, so the average draw is much lower than the figure on the rating plate, but each start-up needs a brief surge. If you want to run one, check two things: that the power station’s surge rating can handle the compressor starting, and that its capacity covers the daily energy use shown on the appliance’s energy label (in kWh per year, which you can divide by 365).
Often you do not need to. A full freezer keeps food frozen for about 48 hours with the door shut, and a closed fridge keeps food safe for about 4 hours. In a longer cut, running the fridge from the power station for short spells, with the door kept shut, may help stretch that time.
Battery chemistry: LiFePO4 vs NMC
Most power stations use one of two types of lithium battery. You do not need to understand the chemistry, but the type affects lifespan, weight and safety.
| LiFePO4 (lithium iron phosphate, also called LFP) | NMC (nickel manganese cobalt) | |
|---|---|---|
| Lifespan | Generally lasts many more charge cycles before capacity fades | Generally fewer charge cycles |
| Weight | Heavier for the same capacity | Lighter and more compact |
| Heat and stability | More stable and less prone to overheating | More sensitive to heat and damage |
| Best for | Home backup kept for years | Carrying around, camping, occasional use |
For a unit that will mostly sit in a cupboard waiting for a power cut, LiFePO4 is usually the better fit. Check the manufacturer’s stated cycle life (often quoted as the number of cycles before capacity drops to a certain percentage) and compare like with like.
Other features worth checking
Pure sine wave output
Mains electricity alternates smoothly. A pure sine wave inverter copies that, so it is safe for laptops, TVs, motors, chargers and sensitive electronics. Cheaper “modified sine wave” units can make some devices buzz, run hot or fail. For home backup, choose pure sine wave.
UPS or pass-through mode
Some units can sit between the wall socket and a device, switching to battery automatically when the power fails. Check how fast the switch happens. A short gap may restart a router or computer, which is a nuisance rather than a danger. For anything critical, ask the device maker whether that model is suitable. If your main aim is keeping the internet up, compare a power station with the cheaper options in how to keep your Wi-Fi on in a power cut.
Sockets and ports
- Enough UK three-pin sockets for what you want to run at once.
- USB-C ports with enough output to charge a laptop directly, which wastes less energy than using the AC socket.
- A 12V car-style socket for DC devices such as some routers and cool boxes.
Charging speed and options
Look at how long it takes to recharge from the mains, from a car’s 12V socket and from solar panels. A power station that takes a whole day to charge from the wall is less useful if you get two short cuts in a week.
Weight and size
Larger capacity means more weight. Make sure whoever is likely to move it can lift it safely, especially if it will be stored upstairs or carried to a bedroom at night.
Using solar panels with a power station
Folding solar panels can top up a power station during a long cut, but UK output varies a lot with season and weather. In winter, when storms cause the longest power cuts, days are short and the sun is low, so expect much less than the panel’s rated watts.
- Check that the panel’s voltage and connector match the power station’s solar input.
- Angle the panel towards the sun and move it during the day.
- Treat solar as a bonus, not the main way you charge, especially from October to March.
This is separate from rooftop solar. A normal grid-tied rooftop system switches itself off in a power cut for the safety of engineers working on the lines, even on a sunny day.
Using a power station for medical equipment
Many people buy a power station to keep a medical device running. That can be a sensible part of a plan, but it must be agreed with whoever supplies the equipment. Ask them about the device’s power draw, whether a battery power station is suitable, and how long its own battery lasts.
Our guide to medical equipment and power cuts explains how to put a plan together. Anyone who relies on equipment that needs electricity should also join the Priority Services Register with their network operator and energy supplier.
Safety: If someone’s life depends on a medical device and the backup is running out, call 999. Do not wait to see how long the power cut will last.
Charging and storing it safely
Lithium batteries are generally safe when used as intended, but large ones store a lot of energy. The Scottish Fire and Rescue Service’s lithium-ion advice applies here too.
- Use only the charger and cables supplied or approved by the manufacturer.
- Do not charge it overnight, while you are asleep or while you are out. Unplug it when it is full.
- Never cover it while charging, and keep it away from anything that burns easily.
- Do not keep it in an escape route such as a hallway or by the front door.
- Store it somewhere cool and dry, away from radiators and freezing outbuildings.
- Stop using it if it swells, smells, gets very hot or is damaged.
- Follow the maker’s advice on storage charge. Many recommend keeping it partly charged and topping it up every few months.
Tip: Put a reminder in your phone to check the power station’s charge every three months. A unit that has slowly run flat in a cupboard is no help when the lights go out.
Frequently asked questions
Can I use a portable power station indoors?
Yes. Battery power stations produce no exhaust fumes, so unlike generators they can be used inside. Keep them ventilated, uncovered and away from anything flammable.
What size power station do I need for a power cut?
It depends on what you want to run and for how long. Add up the watt-hours each device needs, divide by about 0.8 for losses, and choose a unit with more capacity than that total. Phones, lights and Wi-Fi overnight need far less than a fridge or medical equipment.
Will a power station run my fridge?
Many mid-size and larger units can, as long as the surge rating covers the compressor starting. Capacity decides for how long. Running it in short bursts is often enough to keep food cold.
Can a power station run my central heating?
Most gas boilers are wired into the house, so they cannot simply be plugged into a power station. Do not attempt to rewire one yourself. Speak to a Gas Safe registered engineer or qualified electrician about safe options.
Is it worth having a power station as well as power banks?
Power banks are enough for phones in a short cut. A power station makes sense if you want to keep a router, lights, a laptop or a medical device going, or if you often have long cuts.
Your next step: list the devices you would want running in a power cut, note their watts from the labels, and run the numbers through our battery backup calculator before you compare models. If the power is off now, check your postcode for the latest estimated restoration time.
Sources
- Be Ready (UK Government) u2013 Power cuts
- Be Ready (UK Government) u2013 Be ready for emergencies
- Scottish Fire and Rescue Service u2013 Lithium-ion batteries
- National Grid Electricity Distribution u2013 Power cut safety first
Checked against these sources on 28 October 2026. Rules and amounts can change – your network operator or Ofgem has the final word. Spotted something out of date? Tell us.
More on being prepared: Power Cut Emergency Kit: What to Keep at Home · All power cut guides