UK solar park shut over grid limits, costing investors £2m
Britain's largest community solar project has been ordered to close for the summer, exposing the financial risks retail investors face when grid infrastructure fails to keep pace with renewable energy capacity.
The Derril Water solar park in north Devon has been forced offline until September after the National Energy System Operator (Neso) ordered National Grid to switch off a key super-grid transformer. The precautionary measure was taken to prevent local rooftop solar generation from pushing transmission network voltages beyond safe limits during the summer months.
The shutdown is expected to cost the cooperative’s nearly 10,000 members approximately £2m in lost revenue. The project, financed by £20m raised from members and a £22m long-term bank loan, does not expect to receive any compensation or insurance payouts to cover the summer losses.
The curtailment underscores a critical bottleneck in the UK’s energy transition, where local grid infrastructure is failing to keep pace with the rapid expansion of decentralised renewable generation. Surges in rooftop solar power during long, sunny days create voltage management challenges that typically require specialist equipment to resolve.
However, those necessary network upgrades near the Derril Water site have been delayed. The volunteer board managing the park believes the network constraints have been known since 2023, with the required equipment originally scheduled for installation by the end of 2025 but now pushed back to September of this year.
This financial hit compounds a troubled history for Britain’s largest community solar project. The scheme was originally developed by Ripple Energy, which marketed the park to households as a way to earn average savings of at least £200 a year on their energy bills.
Ripple Energy went bankrupt in early 2025, brought down by construction delays and rising costs before Derril Water could even begin operations. The park eventually started generating electricity last September under its cooperative board, after Ripple was bought out of administration by the business energy provider 1st Energy.
In a letter to members, the board said the timing of the shutdown "could not be worse" and would "substantially impact" the scheme’s finances. The board noted the order was "enforced on our solar park and other generators in north Devon with no warning," adding that it "does seem the network operators knew there was a looming problem."
Despite the "unexpected financial pressure," the board reported that most members understood the fault lay with the grid rather than the solar park's management. A spokesperson for National Grid confirmed it curtailed some generation in the local area to keep the system secure and stated it is "working with Neso to help provide solutions to these temporary constraints." Neso declined to comment.
