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Solar Panels and Your EPC Rating: How Much Can They Help?

An Energy Performance Certificate tells buyers, tenants, and mortgage lenders how energy-efficient your property is. Solar panels can push a rating up by a meaningful amount, but only if the installation is MCS-certified and a new EPC is commissioned afterwards.

Helpful video. The Certificate Lab's guide "How To Improve Your EPC Rating With Solar Panels" explains how the SAP calculation treats solar generation and what a realistic rating improvement looks like. The Certificate Lab is a UK EPC and compliance certificate provider.

MCS certification matters for your EPC. If your solar installation is not MCS-certified (or certified under an equivalent recognised scheme), a domestic energy assessor must treat the panels as producing zero output in the SAP calculation. A system that cannot be included in SAP adds nothing to your EPC score, even if it is generating electricity every day. This catches some homeowners who installed panels through an unregistered installer.

1. What an EPC rating is and why it matters

An Energy Performance Certificate rates a property's energy efficiency on a scale from A (most efficient) to G (least efficient). It is calculated using Standard Assessment Procedure (SAP), a government-approved methodology that models the energy demand and supply of the building, including heating, hot water, lighting, and any renewable energy systems installed.

EPCs matter in three specific situations. First, landlords in England and Wales must hold a valid EPC for any rental property, and the Minimum Energy Efficiency Standards (MEES) regulations prohibit new lets on properties below EPC E, with the government's intention (as of 2026) to require EPC C for new tenancies by 2030. Second, sellers must provide a valid EPC to buyers during conveyancing, and a better rating can support the asking price. Third, some mortgage lenders offer preferential rates on properties above a certain EPC band, sometimes called green mortgages.

2. How solar panels are assessed in SAP

SAP models a solar PV array by calculating the annual electricity generation based on the system's kWp rating, the roof's orientation and tilt angle, an estimate of shading, and the UK's regional solar irradiance data. That generated electricity is offset against the home's modelled demand, reducing the calculated energy cost and improving the SAP score.

For a 4kW (4kWp) south-facing system at a 30 to 40 degree pitch with minimal shading, the SAP improvement is typically in the range of 8 to 15 points. Points translate to EPC band movement differently at different points on the scale: a home starting at 50 SAP (low EPC D) needs 10 additional points to reach 60 SAP (low EPC C). A home already at 58 SAP might reach EPC C with only 3 to 4 extra points, meaning a smaller system can be enough.

Rough SAP improvement by system size

  • 2kWp system: typically 4 to 8 SAP points depending on orientation and pitch.
  • 4kWp system: typically 8 to 15 SAP points, the most common residential size.
  • 6kWp system: typically 12 to 20 SAP points, subject to diminishing returns as modelled generation begins to exceed modelled demand.

These are indicative figures. A registered domestic energy assessor will calculate the precise improvement for your property using SAP 10.2 or the current approved methodology.

3. The MCS certification requirement

For a solar PV system to be included in a SAP assessment, the assessor needs to be satisfied that the system exists and is operational. In practice, this means presenting an MCS certificate, issued by an MCS-registered installer at the point of commissioning. Some assessors also accept Microgeneration Certification Scheme equivalent certificates from other approved schemes, but MCS remains the standard for domestic installs in Great Britain.

If your system was installed without MCS certification, an assessor has no approved route to include it in SAP. The panels will appear visually on the roof, but the SAP model will treat the property as if they are not there. Some homeowners in this situation have had systems retrospectively assessed and, where possible, MCS-registered, but this is not always achievable and the process is more involved than commissioning correctly in the first place.

4. Getting a new EPC after installation

An EPC issued before your solar installation will not reflect your panels. You need to commission a new one once the system is up and running, with the MCS certificate in hand.

Registered domestic energy assessors (DEAs) can be found through the Elmhurst Energy, CIBSE, or Stroma accreditation schemes, or through the Energy Performance of Buildings register at gov.uk. The assessment itself takes around 45 minutes for a typical house. The assessor will note the array's orientation, pitch, kWp rating, and any visible shading before running the SAP calculation on site or in their software package. The new certificate is lodged on the register, replacing the old one, and you receive a copy.

5. Solar panels and the 2030 EPC C landlord deadline

The government's stated intention is that all rented properties in England and Wales must achieve EPC C before new tenancies can be granted from 2030. This is not law yet as of September 2026, but most landlords are planning ahead, and MEES enforcement by local authorities has been tightening.

For a property currently at EPC D, a 4kWp MCS-certified solar installation is often enough to reach EPC C without any other changes. For properties at EPC E, solar will usually help but is unlikely to close the full gap on its own. The most cost-effective approach for lower-rated properties is usually a combined programme: loft insulation, draught-proofing, and solar together, with a whole-home energy assessment before committing to any single measure.

Properties in conservation areas or with listed building status may face planning constraints that limit or complicate solar installation. If you are a landlord in that situation, see our separate guide to solar in conservation areas before assuming panels are straightforward to fit.

Frequently Asked Questions

How many EPC points do solar panels add?

A 4kW south-facing solar PV array typically adds between 8 and 15 SAP points, depending on roof pitch, orientation, and shading. That is often enough to shift a property from EPC D to C, or from C to B. The precise figure comes from a registered energy assessor running the SAP calculation for your specific roof and system, not from a general estimate.

Do I need a new EPC after installing solar panels?

There is no automatic legal requirement to update your EPC after installing solar, but if you want the improvement reflected in your rating, for renting, selling, or MEES compliance, you will need to commission a new one from a registered domestic energy assessor. They will need your MCS installation certificate to include the solar generation figures in the calculation.

Can solar alone get my property to EPC C for the 2030 landlord deadline?

For many EPC D properties, a properly sized MCS-certified solar PV system will be enough to reach EPC C on its own. For properties starting at E or below, solar alone is unlikely to close the full gap: draught-proofing, loft insulation, and heating improvements are usually needed alongside it. A combined EPC assessment and energy survey will identify the most cost-effective route for your specific property.

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