Elmhurst Energy published an analysis on 19 May 2025 of how much solar photovoltaic capacity new homes should carry under the Future Homes Standard, ahead of the Government's expected response to its 2023 consultation1.
The consultation, launched in 2023, set out two options for the performance standards of a new home. Option 1 includes a requirement for solar PV on the roof; Option 2 does not include a solar PV requirement1. Under Option 1, the proposed installation is calculated as (40% of the ground floor area) divided by 4.51. Elmhurst states this figure assumes an optimal configuration where the array would be south facing, on a pitch of 45 degrees and with no overshading1. It represents an increase on the solar PV in the Part L 2021 notional dwelling, as panel efficiency improved from 6.5 m2/kWp to 4.5 m2/kWp, with Government expecting manufacturers to meet that efficiency by the time the standard takes effect1.
Elmhurst notes that under current Building Regulations, Part L does not specify the use of any specific technology, instead setting performance targets using a "notional dwelling" and leaving developers free to choose how they meet them1. It reports considerable debate over how much solar PV can realistically be installed on new homes, citing cost, embodied carbon, the availability of high-efficiency panels and varying roof designs, and states that some developers have house designs which struggle to meet the Part L 2021 solar PV requirement and are concerned they will not meet the proposed amount under the Future Homes Standard1. Elmhurst says it believes installing solar PV on new homes is a sensible proposal given the move towards electrification of heating and the current unit cost of electricity, but that the amount required needs to be viable and cost effective, against the backdrop of the manifesto promise to build 1.5 million new homes during this parliament1.
In its response to the consultation, Elmhurst supported the Option 1 notional dwelling containing solar PV, but suggested the orientation of the array be changed to South-East facing so developers could meet or get closer to the notional dwelling amount in properties without south facing roofs1.
"We now await the Government's response to the consultation, expected later this year."
Why it matters for households
The notional dwelling is the reference home against which a real new build's performance is assessed, so whether it contains solar PV, and how much, shapes what is installed on the roofs of homes that are actually built. A requirement expressed as a proportion of ground floor area, rather than a fixed panel count, means the practical effect varies with the size and roof design of each house. For a household, an array fitted at the design stage is generation capacity built into the home from the start, rather than added later, and it reduces the amount of electricity a home draws from the grid. The consultation options differ on whether that capacity is required at all, so the eventual decision affects both the running costs a new home can expect and how far it can meet its own demand. The Future Homes Standard Option 1 vs Option 2 comparison sets out how the two approaches differ, and the carbon reduction expected under the standard covers the emissions side. How such rules are proposed and settled is explained in Energy Consultations: How Rules Are Proposed, Decided and Changed.
What happens next
Elmhurst states that the Government's response to the consultation is expected later in 2025, and that it will confirm the final specification of the notional dwelling, including any requirement for solar PV, providing clarity for developers and assessors1. Elmhurst adds that the final outcome is likely to differ from the initial consultation proposals, reflecting industry feedback and practical concerns raised during the process1. No date beyond "later this year" has been reported1.
Sources1 cited
- How much solar PV should a new home have? - Elmhurst Energy, elmhurstenergy.co.uk