Solar PV for SAP, SBEM and Part L Compliance

Solar PV for SAP, SBEM and Part L Compliance

A lot of new homes, conversions and commercial buildings now need solar panels to pass Part L, or to reach the EPC rating the client or the tenant wants. We work out exactly how much PV the building needs, put it in the SAP or SBEM model, and can introduce you to a trusted MCS-certified installer for a supply and fit quote. You get one team for the calculation and one call for the panels.

Homes: new builds and conversions

• New homes that miss the Part L targets. If the design-stage SAP fails on primary energy or emissions, PV is often the cheapest fix once the fabric and heating are settled.
• Conversions and flats. Electric heating with a hot water cylinder is common in conversions, and it usually needs some PV to pass.
• A target EPC rating. Developers and landlords who want a B rather than a C.
• The Future Homes Standard. From 24 March 2027 most new homes will need solar panels as standard. See our industry updates.

Commercial buildings

• New buildings that fail the BRUKL. If the SBEM fails on primary energy or emissions, PV on the roof is often one of the simpler fixes. See what a BRUKL report checks.
• Existing buildings working towards EPC B. PV can lift a commercial EPC rating, alongside lighting, heating and controls. See our EPC B by 2031 guide.
• Planning. London Plan schemes have to show renewable energy on site in the energy statement (the "Be Green" stage), and PV is the most common choice. See energy statements.

How we size it

We run the options in the SAP or SBEM and tell you the smallest system that works, in kWp, with the roof orientation it needs. No guessing and no oversized quotes. Two recent examples:

• A flat conversion in south-east London needed 2.5 kWp facing south, with no battery, to pass Part L.
• A home in south-east London needed about 5.5 kWp to reach EPC B. The installed system was 5.66 kWp, with no battery.

A battery is not usually needed to pass SAP or SBEM. It can still make sense for your bills, and the installer can price both.

What the installer does

• A survey to confirm the panel layout, cable routes and where the inverter goes.
• The network operator paperwork. Larger systems, which includes most commercial roofs, need approval before installation, which can add a couple of weeks, so order early.
• Supply, scaffolding where needed, installation and the MCS certificate.

We may receive an introduction fee from the installer.

What we need to finish your as-built SAP or BRUKL

• The MCS certificate or the installer's commissioning details
• The system size in kWp, the orientation and pitch of the panels
• Any battery details

Once we have these and the air test result where one is needed, we issue the as-built SAP or BRUKL, the compliance report for building control and the EPC.

Questions we get asked

Do you install the panels yourselves?
No. We are energy assessors. We size the system in the SAP or SBEM and introduce you to an MCS-certified installer, who quotes and installs it.

Do you do solar PV for commercial buildings?
Yes. For a new commercial building we size the PV in the SBEM model so the BRUKL passes. For an existing building we show what PV does to the commercial EPC, alongside lighting, heating and controls. The installer then quotes for the roof.

Will solar panels alone make my design pass?
Not always. Insulation, windows, heating, lighting and the air test all count. We tell you which change costs least, and PV is one of the options.

Do I need planning permission?
Many homes and commercial buildings can add roof panels without it, but listed buildings, some conservation areas and panels that stick out more than 20 cm from the roof can need consent. Check with your council.

Can you finish the EPC before the panels go in?
No. The as-built SAP or BRUKL and the EPC have to show what is actually installed, so we finish them once we have the installer's certificate.

Related: SAP calculations and EPCs, SBEM and BRUKL, commercial EPCs, new dwellings, retrofit projects and EPC B upgrade plans.

Send us your drawings, your SAP or your BRUKL by email or WhatsApp. We will tell you how much PV you need, with a free quote and a turnaround time.