No, most UK solar panels stop working the moment there’s a power cut – a standard grid-tied system is legally required to shut itself down automatically during an outage, for the safety of engineers working on the network. The exception is a solar-plus-battery system specifically fitted with backup or “islanding” capability, which can keep some or all of your home powered, but only if that feature was actually included and configured at installation.
Why Standard Solar Systems Shut Down in a Power Cut
Grid-tied inverters include a safety feature called anti-islanding protection, which automatically disconnects the system from the local network the moment it detects the grid has gone down. This exists to protect engineers who might be working on what they assume is a dead line – without it, your solar system could keep feeding electricity into a “downed” section of network that’s supposed to be safely isolated. It’s a legal requirement for grid-connected systems, not a design flaw, and it means a standard solar installation with no battery genuinely does nothing for you during a cut, even in bright sunshine.
What Actually Keeps the Power on During an Outage
| System type | Works during a power cut? | Why |
|---|---|---|
| Standard grid-tied solar (no battery) | No | Anti-islanding protection shuts the system down |
| Solar + battery, standard grid-tied setup | Usually no | Most batteries are also configured to shut down with the grid unless backup mode is specifically enabled |
| Solar + battery with backup/EPS (Emergency Power Supply) function | Yes, for connected circuits | Isolates itself from the grid and powers your home independently |
| Fully off-grid system | Yes, by design | Never connected to the grid in the first place |
The key word is “usually” in that second row: simply having a battery doesn’t guarantee backup power. Many domestic battery installations are set up purely to shift and store energy for bill savings, with no backup mode configured at all, so it’s genuinely worth checking rather than assuming your specific system has this capability.
How Backup-Power Battery Systems Actually Work
A battery with genuine backup capability includes hardware (often called an Emergency Power Supply, or EPS, function) that detects the grid going down and switches your home to run from the battery and any solar generation, isolated from the grid, within a fraction of a second to a few seconds. Many systems don’t back up your whole house by default – instead, specific circuits (lighting, fridge-freezer, internet router, for example) are wired to a backup consumer unit, so those keep running while less essential circuits don’t. Whole-home backup is possible but typically needs a larger battery and specific installation design to support your home’s full peak demand.
Checking Whether Your Own System Has Backup Capability
Look at your installation paperwork for mentions of “backup,” “EPS,” “islanding mode” or a separate backup consumer unit, or simply ask your installer directly whether your specific battery and inverter combination supports it. If you’re considering adding this capability to an existing system, or specifying it for a new one, it’s worth raising explicitly during quoting rather than assuming any battery automatically includes it – our guide to what size solar battery you need covers sizing considerations if backup power is a priority.
Frequently Asked Questions About Solar Panels and Power Outages
Will my solar panels work if the power goes out?
Not on their own. A standard grid-tied system, even with plenty of sunshine, is designed to shut down automatically during a power cut for safety reasons, unless it’s specifically paired with a battery that has backup capability enabled.
Do I need a special battery for power-cut backup?
You need a battery and inverter combination specifically configured for backup (often called EPS or islanding mode), not just any battery. Not all domestic battery installations include this, so it’s worth confirming with your installer rather than assuming.
Can a backup battery power my whole house during an outage?
It depends on the system’s design. Many backup setups power a limited set of circuits (lighting, fridge, internet) rather than the whole house, since covering full peak household demand needs a larger battery and specific installation planning. Whole-home backup is achievable but should be discussed and sized specifically for that purpose.
Why do solar systems have to shut down during a power cut?
It’s a safety requirement called anti-islanding protection, which prevents your system from feeding electricity into what should be a de-energised section of the network while engineers may be working on it. It’s a legal requirement for grid-connected inverters, not an optional feature.
