Rooftop solar installations in the UK hit a record 1.3 gigawatts in 2023 – enough to power 400,000 homes. But the grid was built for a world where power flows one way: from power station to plug socket. Now, on sunny afternoons, thousands of homes are feeding electricity back into the same cables, and those cables are starting to groan.
The Times reported this week that engineers are scrambling to prevent a grid crisis as solar capacity surges faster than network upgrades can keep pace. The article, headlined ‘Solar power is booming. Now engineers must prevent a grid crisis’, highlights the tension between the government’s net-zero ambitions and the physical reality of ageing infrastructure.
Why the grid is struggling
The problem is local, not national. In parts of Cornwall, East Anglia, and the South West, Distribution Network Operators (DNOs) have already paused new solar connections because the low-voltage cables cannot handle the midday export surge. Ofgem data shows that 12% of new solar applications in 2023 faced at least a six-month delay due to grid constraints. For a homeowner expecting a quick payback on a £6,000 system, that wait can kill the financial case.
But even where connections are granted, the risk of ‘export curtailment’ is rising. DNOs can remotely throttle your inverter on sunny days, cutting your export income to zero. The Energy Saving Trust estimates that a typical 4 kWp system in southern England could lose £150–£200 a year if curtailment becomes routine.
What this means for your solar investment
The days of simply slapping panels on a south-facing roof and pocketing the Smart Export Guarantee (SEG) payments are fading. The SEG rate itself has already dropped – from an average 5.5p/kWh in 2022 to around 4p/kWh today – and grid constraints will push it lower. The catch is that without battery storage, you are exporting at the worst possible time: when everyone else is exporting too.
Battery storage changes the maths. A 5 kWh battery – costing roughly £4,000 installed – can store midday solar for evening use, reducing export curtailment and increasing self-consumption from 30% to over 70%. That cuts grid purchases by about 2,500 kWh a year, saving £500 at current price cap rates. The battery also acts as a buffer against future curtailment orders.
Who qualifies – and who doesn’t
Not every homeowner will hit grid limits. If you live in a city with strong local transformers and few other solar homes, you are likely fine. But if your postcode falls in a ‘constrained area’ – check your DNO’s capacity map online – you should think twice before installing without storage. Some DNOs now require a ‘non-export’ agreement for new connections, meaning you cannot feed power to the grid at all. In that case, a battery is not optional; it is mandatory to make the system work.
The government’s new ‘flexibility service’ trials, run by National Grid ESO, pay households to reduce export during peak solar hours – effectively a reverse of the usual demand-side response. But the payments are small: typically £50–£100 a year per household. Not enough to cover the lost export revenue.
What you can do now
First, check your DNO’s connection queue. If they are taking more than 12 weeks to approve a solar application, that is a red flag. Second, insist on a quote that includes battery storage – even if you stretch the budget. The payback period for a solar-plus-battery system is now shorter than for solar alone in constrained areas. Third, ask your installer about ‘export-limiting’ inverters that can be remotely managed but still allow self-consumption.
Ofgem is consulting on new rules to force DNOs to publish real-time capacity data by postcode. That should be mandatory, not voluntary. Until then, homeowners are flying blind. The solar boom is real, and it is welcome. But without a grid that can handle it, the boom will hit a brick wall – and your panels will sit idle on the sunniest days.
Frequently Asked Questions
No – your panels will still generate electricity for your home. But if your inverter is remotely curtailed by the DNO, you may be unable to export surplus power to the grid, reducing your SEG income. Battery storage prevents this by storing the excess for later use.
Contact your Distribution Network Operator (DNO) – find them via the Energy Networks Association postcode tool. Ask about their 'capacity map' or 'connection queue times.' If they report high congestion or long delays, consider adding battery storage or a smaller system that is less likely to trigger curtailment.
