UK's Largest Community Solar Farm Shut Down for Summer to Prevent Grid Overload
Britain's biggest community-owned solar project, Derril Water solar park in north Devon, has been ordered offline for the summer by the National Energy System Operator to avoid overloading the local grid, costing its nearly 10,000 members an estimated £2 million in lost revenue.
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Britain's largest community-owned solar project, the Derril Water solar park in north Devon, has been forced to shut down for the summer after the National Energy System Operator (Neso) ordered its disconnection to prevent overloading the local grid. The shutdown began before a recent European heatwave and is expected to cost the cooperative's nearly 10,000 members an estimated £2 million in lost revenue before the park can restart in September.
In a letter to stakeholders, the cooperative's board described the shutdown as "unexpected" and said it was "enforced on our solar park and other generators in north Devon with no warning." The timing, at the start of the project's first summer, "could not be worse," the board stated, and will "substantially impact" the scheme's finances, including payments to members.
Neso ordered National Grid to turn off a "super grid transformer" over the summer to prevent rooftop solar in the area from pushing transmission network voltage beyond safety limits. The surge in rooftop solar is particularly challenging to manage during long, sunny summer days when generation exceeds local demand. Specialist equipment to address voltage issues has not yet been installed in the area near Derril Water.
The board believes problems with the north Devon network have been known since 2023, with new equipment originally due by the end of 2025. However, those upgrades were delayed and are now scheduled for completion in September 2026, the same month the solar park is expected to resume operations.
Derril Water was funded by £20 million raised from cooperative members and a £22 million long-term bank loan. It began generating electricity in September 2025 after its original developer, Ripple Energy, went bust in early 2025 due to construction delays and rising costs. Following Ripple Energy's collapse, business energy provider 1st Energy acquired the company out of administration.
A National Grid spokesperson confirmed that generation in the local area has been curtailed to keep the system secure and that the company is working with Neso to find solutions to the temporary constraints. When contacted for comment, Neso did not respond.