— reviewed against the regs as they stand.
Why PV dominates new-build compliance
Solar photovoltaic panels generate electricity from daylight, directly reducing a dwelling’s modelled energy demand and CO₂ emissions. The SAP 10 notional dwelling includes an assumed PV array — roughly 4kW for an average house — so a dwelling without PV starts behind its target and must make the difference up elsewhere. In practice, PV (or a heat pump) is how most SAP 10 passes are achieved.
PV is also the most common answer to planning conditions requiring a percentage CO₂ or energy demand reduction from renewables.
What affects the SAP contribution
Array size (kWp), orientation and pitch (south-facing ~35° is ideal; east/west loses ~15–20%), and overshading. SAP 10 allows MCS overshading data instead of defaults, and now recognises battery storage and PV diverters (which dump surplus generation into the hot water cylinder). For flats, only dwellings directly connected to an array get the benefit — landlord-supply arrangements no longer count for everyone.
Practical notes
Panels are typically roof-mounted on-roof or integrated (in-roof trays look cleaner on new builds and avoid raised fixings). No moving parts, 25-year+ panel warranties, minimal maintenance. Tell us early if PV is in the design — sizing it precisely against the SAP calculation avoids paying for panels you don’t need.