Britain’s Largest Community Solar Farm Shut for Summer Over Grid-Overload Fears

The National Energy System Operator (Neso) ordered the National Grid to curtail generation at the Derril Water solar park in north Devon for the entire summer of 2026. The precaution was taken to avoid a “thermal overload” of the local transmission network, which officials said could be triggered by the region’s high concentration of rooftop solar during prolonged sunny periods. The shutdown began the Friday before the half-term heatwave and will remain in place until the park can restart in September.

The Guardian

Derril Water, funded with £20 million from cooperative members and a £22 million bank loan, was intended to be Britain’s first shared-ownership solar park. Initial plans by Ripple Energy aimed for operation in 2024, but construction setbacks and rising costs led Ripple into administration in early 2025. The volunteer board, later backed by energy provider 1st Energy, finally brought the park online in September 2025. Upgrades to a “super-grid transformer” that would manage voltage spikes were slated for completion by the end of 2025, but the work was delayed and is now expected only by September 2026.

The Guardian

The summer curtailment is projected to cost the cooperative’s nearly 10,000 members about £2 million in lost revenue. With no compensation or insurance coverage anticipated, the board warned that the interruption creates “unexpected financial pressure” and could affect near-term member payments.

The Guardian

The cooperative’s board emphasized that the issue lies with the grid, not the solar park’s management. A National Grid spokesperson confirmed the curtailment, adding that the company is “working with Neso to help provide solutions to these temporary constraints.” Neso declined to comment further.

The Guardian

• “enforced on our solar park and other generators in north Devon with no warning” — Board, Derril Water cooperative

The Guardian

• “It said: “The interruption creates unexpected financial pressure and will impact our ability to pay members at least in the near-term.” — Board, Derril Water cooperative

The Guardian

• “We are not clear on what triggered the shutdown, which came on the Friday before the half-term heatwave with no notice,” — Board, Derril Water cooperative

The Guardian

• “Although there has been some justified frustration, the majority of the coop’s 9,500 members who have been in touch understand that the issue does not lie with the solar park, nor its management through the park’s volunteer board of directors,” — Board, Derril Water cooperative

The Guardian

• “We’re now working with Neso to help provide solutions to these temporary constraints,” — National Grid spokesperson

The Guardian