Solar PV & Home Batteries

At the time of writing the methodology for EPC assessments of existing dwellings is RDSAP 9.94. The much anticipated RDSAP 10 update has not happened yet and a significant methodology overhaul from RDSAP to the Hone Energy Model (HEM) is proposed for 2025.

Solar PV is a shorthand way of referring to Solar Photo-Voltaic panels. These are panels that when exposed to sunlight generate electricity which can then be fed back into your property to offset your electricity use.

These panels are in contrast to the other type you may occasionally come across called Solar Thermal panels. Solar Thermal panels contain pipes through which water is heated by the sun and circulated to heat up water stored in a Hot Water Cylinder.

Solar Thermal panels have fallen out of favour, with preference now given to Solar PV panels instead, the price of which has fallen in recent years.

Solar PV could be a 'get out of jail' card for your property if you need to improve your EPC rating for MEES requirements.

Solar PV is often listed as a recommendation on EPCs to improve your rating, and the gains can be fairly significant.

When an energy assessor records the presence of Solar PV at your property they would ideally like to see the MCS Certificate that you would have been provided with at the time of installation.

All solar PV installers need to be registered with the Microgeneration Certification Scheme (MCS), and the certificate they provide will detail the capacity of the Solar Installation (in kWp), the orientation and the elevation of the panels.

This information is useful for the EPC assessment. If it is not available then the Domestic Energy Assessor can instead enter some generic information about the installation but the information will not be as accurate as that provided by an MCS certificate.

Let's take a look at what difference Solar PV makes to my property, a 1950s mid-terraced 3-bed house with a gas condensing boiler, no cavity wall insulation, and 200mm loft insulation (We cover this property in our Case Study 2):

So Solar PV makes a considerable difference to the EPC rating for this property.

At the time of writing, home batteries cannot be included within an RDSAP EPC - that's the type of EPC used for an existing dwelling, rather than a new build.

There is a methodology update to RDSAP due soon but it keeps getting delayed. Under that new version 10 of RDSAP, home batteries can then be included in an assessment, but this will only be supported when solar PV is also present.

If you have a Home Battery installed without solar then you still will not be able to include it in the EPC assessment.

If you are able to include your home battery because you also have solar, then the home battery should improve the rating of your EPC. By how much we will have to wait and see.

Click here to return to our 'Improve Your EPC' main page, and see if there is another way you could improve your EPC rating.