With storm season bringing the usual run of power cuts across Hampshire, it’s worth clearing up one of the most common misunderstandings about solar panels. A lot of people assume that if you’ve got panels on the roof, you’ll have power when the grid goes down, especially on a bright day. In reality, for most systems, that’s not what happens at all, and it’s a genuine surprise to a lot of homeowners the first time it happens to them.
Why your panels switch off, even in bright sunshine
Standard grid-connected solar systems are required by law to shut down automatically the moment the grid loses power, regardless of how sunny it is outside. This is called anti-islanding protection, and it’s built into every UK-compliant solar inverter. According to the Energy Networks Association’s Engineering Recommendation G98, the standard governing how small-scale generators like home solar connect to the network, an inverter must disconnect within two seconds if it detects the grid voltage or frequency moving outside strict, defined limits, exactly what happens the instant a power cut occurs.
To put the numbers on it, G98 specifies that a system must disconnect if grid voltage moves outside roughly ten percent of the standard 230V supply, or if frequency drifts outside a 47 to 52 Hz range, both of which happen almost instantly the moment a section of the network loses power. Your inverter is constantly watching for exactly these conditions in the background, entirely invisibly, until the moment it needs to act.
The reasoning behind this isn’t bureaucratic caution, it’s a genuine safety measure. When engineers are called out to fix a fault or downed line, they need to know with certainty that the line is dead. If solar systems kept feeding electricity into what should be a de-energised network, an engineer working on what they believe is a safely isolated line could be seriously injured. Your system switching off isn’t a fault or a design flaw, it’s doing exactly what it’s legally required to do, and honestly, it’s a reassuring thing to know is happening automatically rather than something you’d want to override even if you could.
This applies whether or not you’ve got a battery too
It’s a common assumption that having battery storage automatically solves this, and that’s not quite right either. A standard battery system, installed purely to store surplus solar generation for later use, still shuts down along with the rest of the system during a power cut unless it’s been specifically designed and wired with backup functionality in mind. Storing electricity and providing electricity during a grid outage are two genuinely different capabilities, and a system can absolutely have one without the other. It’s a distinction well worth understanding before an outage, rather than discovering it by trial and error the first time your street loses power and the house goes dark despite the battery sitting there fully charged in the garage.
How you actually get backup power during a power cut
Getting real power cut resilience requires a system specifically built for it, generally referred to as an Emergency Power Supply, or EPS. According to Sunsave’s guidance on home battery backup for power cuts, this typically means an EPS-capable inverter, a battery with sufficient capacity, and an automatic transfer switch that isolates your home from the grid and switches over to battery power within milliseconds of an outage being detected.
There are different levels this can be set up to provide. Some households opt for a single backup socket, enough to keep a phone charged or a router running. Others move a handful of essential circuits, such as lighting, the boiler controls, and the fridge freezer, onto a dedicated sub-board that stays live during an outage. A smaller number go further still, with a full backup box that can run most or all of the home from battery power, capacity permitting. Which of these makes sense depends on your battery size, your inverter’s capability, and realistically, how long you’d want that backup to last before the battery runs down.
It’s also worth understanding that most backup setups draw purely from whatever charge is already sitting in the battery at the moment the power cuts out, not from your solar panels directly, since the same anti-islanding rules generally still apply to the wider system. Some newer inverter and battery combinations from certain manufacturers can continue generating from solar during a power cut once they’ve switched into an isolated backup mode, but this isn’t universal across all equipment, and it’s exactly the kind of detail worth confirming for your specific setup rather than assuming.
Why this matters more heading into storm season here
Hampshire sees its share of weather-related outages, particularly from Channel storms affecting the coast and tree-fall incidents around wooded areas like the New Forest, and SSEN’s own guidance on power cuts and emergencies reflects a network that plans and prepares for exactly this kind of seasonal disruption. Weather-related faults can take considerably longer to resolve than a straightforward local fault, sometimes stretching well beyond a day in more severe or harder to reach cases, which is exactly the scenario where genuine backup power, rather than solar panels that switch off along with everything else, actually makes a difference.
Ofgem’s Guaranteed Standards of Performance do entitle domestic customers to compensation once an outage passes certain time thresholds, with higher payments during officially declared severe weather events, which is worth knowing about. But compensation arrives after the fact, it doesn’t keep your fridge running, your boiler controls powered, or your home working through the outage itself, which is the practical gap that a genuinely designed backup system is there to close.
Why this needs proper design, not just any battery
Not every battery or inverter combination supports EPS functionality, and retrofitting it into a system that wasn’t designed with backup in mind isn’t always straightforward or even possible without additional equipment. If power cut resilience matters to you, whether that’s for a home office, medical equipment, or simply peace of mind through winter storms, it needs to be part of the conversation from the outset, not an assumption you only test the first time the power actually goes out.
GU Solutions is a NICEIC Approved Contractor and Domestic Installer, and when backup power matters to a household, we design the system around that requirement specifically, rather than letting you find out what your existing setup can and can’t do during the next storm.
What to ask if backup power matters to you
If you’re considering solar and battery storage and power cut resilience is part of the appeal, ask directly whether the proposed inverter and battery combination supports EPS or backup functionality, since not all of them do. Ask what level of backup is realistic, a single socket, essential circuits, or full house, and for how long, given your battery’s actual capacity. And if you already have solar or battery storage installed, ask your installer directly whether backup capability is included, rather than assuming it is. It’s a far better conversation to have now, on a calm afternoon, than partway through a storm when the power’s already gone and you’re finding out the hard way what your system can and can’t do.
Getting power cut resilience that actually works
For homes across Basingstoke, Old Basing, Chineham, Oakley and Sherborne St John, having solar panels doesn’t automatically mean the lights stay on in a power cut, and it’s better to know that now than during the next storm.
If backup power is something you’d genuinely value, GU Solutions is the first port of call. As NICEIC Approved Contractors and Domestic Installers, we’ll design a system that actually delivers it, rather than one that simply assumes it.
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