High Court interprets national policy on ‘overplanting’ in solar energy schemes
Cornerstone Climate, Planning and Environment, Public Law and Judicial Review
The High Court has today handed down judgment in Ross v SSHCLG [2025] EWHC 1183 (Admin) – a test case on the interpretation of national policy concerning the practice of ‘overplanting’ in solar energy schemes (i.e. the arrangement whereby more solar panels are installed than would be needed for a solar farm with a particular maximum AC capacity).
Eyre J has confirmed that National Policy Statement for Renewable Infrastructure EN-3 does not restrict the practice of overplanting to account for degradation in panel array efficiency, but that overplanting may be justified for other reasons too.
Overplanting Not Limited to Panel Degradation
In the present case, the developer had sought to overplant to not only account for panel degradation but to also address: (i) the difference between the maximum output of the panels in laboratory conditions vs the actual output in the field; and (ii) the configuration of the site and fluctuations in the level of sunlight over the course of the day and the year so as to maximise energy generation overall.
The Judge held that the Inspector was correct to conclude that such overplanting which went beyond degradation (the only factor mentioned expressly in the policy) was not in conflict with EN-3 [75]. This was particularly evident when one considers the purpose and context of EN-3 and EN-1 (see [75]-[85]).
Interpretation of Footnote 92 in EN-3
The Judge also grappled with the correct interpretation of footnote 92 in EN-3, which governs when “reasonable overplanting should be considered acceptable”. He confirmed that footnote 92 did not require a separate determination of whether the proposed degree of overplanting was reasonable. Instead, the issue was properly to be addressed as part of the planning balance, which is to be carried out on the basis of the scheme’s full extent, including any overplanting [89]-[92].
The Claimant raised four further grounds of challenge which were similarly dismissed.
The case is essential reading for those involved in solar schemes – whether under the TCPA or NSIP regime. Notably, the issues in this case were raised in the context of a 49.9MW scheme which fell under the NSIP threshold. Nonetheless, EN-1 and EN-3 were recognised as important material considerations and the judgment provides welcome clarification for solar energy schemes which are being progressed under either regime.
Robert Williams and Ruchi Parekh acted for the Secretary of State, instructed by the Government Legal Department.
