In the UK, SAP refers to the Standard Assessment Procedure used to assess the energy performance of residential buildings. For solar PV systems, SAP does not set installation rules but defines how systems are assessed for energy efficiency calculations and EPC ratings. The methodology considers factors like system size, solar panel orientation and tilt, shading, inverter efficiency, and local solar radiation (so it’s fairly complicated). The data is used to estimate annual electricity generation and how much of that power is likely to be used within the home.
For a solar PV system to be recognised in SAP calculations, it must be properly specified and installed, ideally by an MCS-certified installer. And if battery storage is included, SAP also accounts for how stored energy is used.
