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The UK is deploying solar power faster than you might think – but working out exactly how much we have is challenging.
Two sources of data are currently used by the Government to estimate solar deployment. The first is from the standards body for small-scale renewable energy, MCS. It provides data for household rooftop installations and others of comparable scale, up to 50 kilowatts – about 10-15 times larger than a typical home, embracing the likes of small businesses, church halls, junior schools and the like – the typical territory of the community energy movement.
Each installation registered with MCS feeds into the Government figures.
The other source is the planning system, which feeds into the Renewable Energy Planning Database (REPD). That covers anything that requires planning permission to deploy, which nowadays means solar farms. In the early days of solar, it also included rooftop installations but that has long been done away with, as an unnecessary barrier to the sector’s growth.
Going by the official reckoning, there is now 21,848.8 MW of solar capacity, as of April.
The trouble is that this figure is incomplete, due to a significant gap in the data. Rooftop installations can be far larger than the MCS threshold of 50kW. These are reported to no central authority.
To give some context, the largest of these ‘commercial-scale’ installations that is fully commissioned is currently a Jaguar Land Rover factory in the Midlands, at 10.7 megawatts – 200 times larger than the size with which MCS concerns itself.
A couple of years ago, I visited a newly-commissioned rooftop installation of 2MW, mounted on a warehouse that was, quite literally, a mile around. But both pale in comparison to the 25MW system underway at the Port of Liverpool, which will be by far the largest in the country.
So how can we estimate the state of the commercial-scale market, and by extension all of what the UK has in place now?
My friends at Solar Power Portal used a fundamentally different methodology. In confidence, they ask distributors what has been sold each year, then deduct figures from MCS and the REPD, to arrive at an estimate for the commercial-scale market.
Solar Media Market Research analyst Josh Cornes estimated that there was 23.8GW in place on the ground and on rooftops at the end of last year. Putting his estimate of 5.5GW being deployed this year, then a decent guess is that around 26.5GW is currently generating, as of the middle of 2026. That’s almost five gigawatts more than the official estimate.
I should stress that the Department of Energy Security and Net Zero is aware of the issue and is working on resolving it.
This is hardly surprising, considering that there are statutory targets to meet – and every panel counts.
The Clean Power 2030 Action Plan of December 2024 set a headline goal of reaching 45–47GW of solar capacity by the end of the decade. But the tenth footnote of an annex to the plan adds that “an additional 9-10 GW of rooftop solar projects” could deploy before 2030, so the real expectation is that there will be 54-57GW of solar generation capacity by then.
The plan brought forward expectations that were already in place. The British Energy Security Strategy, published in the wake of the full-scale Russian invasion of Ukraine, suggested that 70GW of solar capacity would be installed by 2035.
So, to arrive at a conclusion, we are almost but not quite halfway to reaching the Government’s target of 54-57GW, having got about 47% of the way there.
Considering how much groundmount capacity has planning permission, and how the rooftop market is booming due to yet another energy crisis, I have every confidence that we will meet this goal. Onwards and upwards.
Thanks, Gareth Simkins, Project Manager at Croydon Community Energy and Senior Communications Adviser at Solar Energy Uk for writing this blog. If you’d like to submit a blog post, please email us at hello@croydoncommunityenergy.co.uk
