Solar panels
Home batteries in a power cut
Most home batteries do not supply power in a power cut. Backup needs specific equipment that isolates your home from the grid, and it usually covers only some circuits.
Updated 3 October 2026 · energy.org.uk editorial team
Why most systems switch off
Solar inverters and batteries connected to the grid must shut down when the grid fails, so they don't send electricity into lines that engineers may be working on. Energy Saving Trust notes that most battery storage systems will not provide power during a power cut.
What backup needs
- A battery and inverter that support backup (sometimes called emergency power supply or EPS).
- Equipment that disconnects your home from the grid during the cut, often a separate switch or gateway.
- A decision about which circuits are backed up, such as lights, the fridge, the router and the boiler's controls. Backing up the whole home costs more and needs more battery power.
Some systems switch over automatically; others need you to flip a switch, and there may be a short gap in power.
How long would it last?
Roughly, usable battery capacity (kWh) divided by what you run (kW). A battery with 5 kWh usable running a fridge, lights and router at around 0.3 kW together would last for many hours; an electric shower or oven would drain it quickly or exceed what it can supply at once. The battery may also be partly empty when the cut starts.
Check
What to check first
- Whether your battery and inverter are backup-capable, and whether backup was actually installed.
- Which circuits are covered.
- The battery's continuous power, which limits what can run at once.
- Whether solar panels can recharge the battery during a cut, which depends on the system.
Do
Practical next steps
- Ask your installer whether backup is fitted, which circuits it covers, and how it switches over.
- If you are buying, ask for the backup option to be priced separately.
- Test the switch-over with the installer at handover, if the system allows it.
- If you depend on electricity for medical equipment, join your supplier's Priority Services Register as well.
Take care
Important limitations
- A battery does not replace a proper plan for medical equipment that needs power.
- Backup adds cost and may need extra space and electrical work.
- Call 105 to report or get updates on a power cut in Great Britain.