Renewable Electricity Generation Under the FHBS
The government has created a new legal requirement for renewable electricity generation on new dwellings — a significant change from the original consultation proposal of including solar in the notional building. Here's how it works.
The New Functional Requirement
Instead of including solar PV in the notional building as originally proposed, the government has introduced a new legal requirement (subject to Limits on Application) to install a system for renewable electricity generation when a building containing a dwelling is erected. The system can be installed on the building or within the boundaries of its curtilage. It must be designed to enable generated electricity to be available for use by residents and produce a reasonable output taking account of the building's design and surroundings.
The 40% Coverage Guidance
Approved Document guidance states that the requirement will be met if solar panels equivalent to 40% of each dwelling's ground floor area are installed. However, other methods can be used, and the guidance sets out circumstances where lower coverage is still sufficient — for example, where architectural features, dormer windows, or design considerations prevent full coverage. This flexibility was introduced after consultation feedback that the original proposal would have been impractical in many situations.
Minimum Threshold & Exemptions
If the available roof space cannot produce at least 720kWh per year (roughly equivalent to less than 2 PV panels), no solar panels need be installed. Buildings with a storey at least 18m above ground level that contain dwellings are also exempt — this threshold mirrors the Higher-Risk Building definition. A microgrid provision allows the requirement to be met by a directly connected off-site renewable electricity system.
Non-Domestic Buildings
For non-domestic buildings, solar PV is included in the notional building (not via a functional requirement) at 40% of the building's foundation area for both top-lit and side-lit spaces. This is a reduction from the originally proposed 75% for top-lit spaces, following consultation feedback that this level would be impractical. Unheated buildings with low electricity consumption and certain HRBs are exceptions.