☀️ Solar panels can work in a power cut, but only if they’re installed with a battery and a relay.
☀️ Power cuts cause solar panels to automatically switch off to protect electrical utility workers.
☀️ About 23% of the homes in the UK are affected by power cuts each year, and it’s going up.
Solar panels are getting cheaper year on year, which means more households in the UK can benefit from lower electricity bills and a lower carbon footprint which is great for your wallet and for the planet.
But before you go get solar panels installed, you’ll want to understand everything about them, including how they can keep your home appliances working during a power cut, which happens far too often in the UK now.
But don’t fret, it’s completely feasible. In this guide, I’ll tell you how to achieve this goal, how much it’ll normally cost you, and whether it’s vital for your home.
Do solar panels work in a power cut?
Yes, solar panels can function in a power cut – but only with the right setup from your solar panel installer, who should be an MCS Certified Installer in the UK.
Most solar panel systems will automatically shut down when a power cut occurs, this is to protect the electrically utility workers who could be working on the National Grid electrical system, like on the overhead or underground cables, but for an extra fee, your solar installer can equip your solar panel system with a device that allows it to transfer power from your solar battery to your home when the National Grid fails.
Without this additional option, both your solar panels and your solar battery will be useless during a power cut.
How do you make sure your solar panels work in a power cut?
Solar panels can operate in a power cut by disconnecting from the National Grid – but it requires some planning.
If your home is already off-grid and independent from the National Grid, your solar panels will keep functioning as usual.
Otherwise, you can choose to switch your home off the National Grid temporarily.
How do you temporarily leave the National Grid and go off-grid?
You can temporarily disconnect your solar panel system from the National Grid by adding a relay (a switch) to your solar battery and solar panels that will cut off your solar PV system from the National Grid in the event of a power cut.
Some solar installers call this an Emergency Power Supply (EPS), but it’s only a switch. Your solar PV system will be more expensive with this extra component, but not by much, we’re talking about an extra £350 – £500, in most cases.
The relay (switch) makes sure your solar power keeps your home appliances running, the solar power doesn’t go to the National Grid, in a process called islanding.
Solar islanding is when a home solar panel system continues to generate electricity even though the National Grid is down. Many people would consider this a good thing, as your home still has power from your solar panels while everyone else has no power.
You should also check that your battery inverter can handle all the electricity you need at once, or it could fail.
For example, if your battery inverter is 2kW and you use a 3kW oven, it won’t work, your oven requires too much power.
Look at your home appliances, and think about which ones you’d use during a power cut, and choose the size of your battery inverter based on how much power you’d need at once.
Why don’t solar panels automatically work in a power cut?
Solar panels need to stop working during a power cut for safety reasons, and this is a legal requirement in the UK.
When they’re on, your solar panels give extra electricity to the National Grid. This could harm the electrical engineers fixing the lines if there’s a power cut.
That’s why solar inverters turn off automatically when they sense a sudden power cut.
How long can solar panels power your home in a power cut?
A solar battery can keep your home powered for hours or days with solar panels during a power cut.
The average solar battery can store up to 6.5kWh and the normal 3-bedroom household uses about 8.2kWh per day according to Ofgem, so if you have two 6.5kWh (13kWh) solar batteries or three 3.3kWh (9.9kWh) batteries you should have enough power for a day, or more with full batteries and no energy saving.
You can extend your power for days with 5kWh of solar power if you use it wisely. Just avoid using appliances like a washing machine, a tumble dryer, or your main oven, and don’t boil your kettle too often, get a thermos flask or two.
Sadly, power cuts often occur unexpectedly in the UK, so you may not have a fully charged solar battery ready.
A good solar PV system will usually give you about half a battery of power at any one time, under normal operating conditions.
That should be enough to cover your essential appliances for most power cuts, which don’t normally last more than a few hours, even in the UK.
If you think you need a bigger solar battery for your home, we suggest monitoring your power usage with a smart meter – your energy supplier like British Gas, Octopus Energy, E.ON, or EDF Energy can give you one for free.
When you figure out the solar battery size you need, remember to include anything important that needs steady power, like medical devices or your fridge and freezer.
Will your solar panels charge your battery in a power cut?
Yes, your solar panels can still fill up your solar battery in a power cut – but only with the right configuration.
Your installer should use a battery inverter that can handle more power than the solar inverter, to avoid overloading the battery storage.
Hybrid inverters combine a solar inverter and a battery inverter together in one unit, enabling DC (direct current) power generated by your solar panels to be converted directly to AC (alternating current) or to be passed through to a battery for storage before being converted to AC.
If not, your solar battery might just lose all its stored power when a power cut happens.
With this setup, your solar panels will keep topping up your battery in a power cut, giving you more hours of power if needed.
Should you get a solar battery in case of a power cut?
A solar battery and a relay (switch) can be useful if you often face power cuts in your local area, so you can have power even when others don’t.
UK Power Network estimates that 23% of homes in the UK have power cuts each year and they last 2.5 hours on average, so it’s good to be prepared – especially if you need constant power for important devices, like medical devices.
But if you rarely have power cuts in your local area and you like your solar panel system as it is, you don’t need to buy them.
Most homes in the UK don’t experience any power cuts in a year.
Still, many households that we install solar PV system in buy a solar battery (or two, or three) with their solar panels, so they can make the most of their solar power. If you want to add a battery, consider adding a relay (switch) too.
Remember if you have solar battery storage installed when you have your solar panels installed you pay 0% VAT until April 2027, but if you have solar battery storage installed after your solar panels are installed, as a retrofit, you pay 20% VAT.
You should now know everything about how solar panels and solar battery storage works in a power cut in the UK.
Feeling ready to invest in solar panels and solar battery storage? Want to learn more? Your best option is to talk to one of our friendly solar energy experts on 01268 928 690 or click on the ‘Enquire Now’ button below and we will help you find the right fit for your home and budget. Remember we are both an MCS Certified PV (Panels) Installer and an MCS Certified Battery Storage Installer. MCS Certification is a mark of quality. Our membership of MCS demonstrates our strict adherence to these recognised industry standards; highlighting quality, competency and compliance.
NXTGEN Energy – Your Trusted Solar Energy Partner 💚
Frequently Asked Questions about Solar Panels in Power Cuts
Solar panels can work in a UK power cut or power outage with a special relay in your system. This relay lets you switch smoothly between National Grid power and your solar power. You can keep using solar energy until the National Grid is back, if your solar battery has enough charge.
When your solar battery is full, solar power will supply your home with electricity. If your panels produce more power than your home uses, the extra is lost or can be sold to the National Grid. You can earn money for this extra power with a Smart Export Guarantee scheme. The average 3-bedroom home makes £159 a year. If not, you get nothing.
With the right relay in your solar system, your solar battery will give you power in a power cut. You just need to use less electricity, to save energy and protect your battery inverter from breaking. Look at your battery inverter’s limit, and don’t use more power than that.
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