Does solar PV improve your EPC rating?
If you’re a homeowner getting ready to sell, or a landlord trying to improve an EPC (often to meet rental standards or boost resale value), you’ve probably asked the same thing:
Will solar panels actually improve an EPC rating?
In many cases, yes. Solar PV often improves an EPC because it reduces the amount of electricity the EPC calculation assumes you need to buy from the grid. Less grid electricity (on paper) usually means a better EPC score.
If you’re thinking about installing solar PV, this guide explains how EPCs “score” solar, and what UK export rules mean if you’re considering a larger system.
The short answer: how solar improves EPC scores
An EPC is based on a standard calculation called SAP (Standard Assessment Procedure). Don’t worry about the name the key point is this:
SAP is a model. It estimates how much energy a home would use under typical conditions. It doesn’t look at your actual bills.
Solar PV helps because the model assumes you generate some electricity yourself, so you “need” to import less from the grid. That typically improves both:
- Energy efficiency (how expensive the home is to run), and
- Environmental impact (carbon emissions).
GOV.UK explains that domestic EPCs use the Energy Efficiency Rating / SAP rating.
How to get EPC from D to C
For a lot of homes, moving from D to C is about doing a few upgrades that score well in SAP. Solar PV is often the “final push” that gets you over the line — especially if the basics (like insulation and lighting) are already sorted.
It’s not guaranteed for every property, but solar is one of the upgrades that can:
- help the EPC score, and
- reduce bills in real life (especially if you use electricity during the day).
System sizing rules: can you install 10kW on a single-phase supply?
People often search for “10kW solar systems” because they want maximum savings or to boost the EPC score. The main thing to understand is:
You can often fit a large solar array on a normal home — but there are rules about how much you’re allowed to export back to the grid.
Who sets the export rules?
Your local electricity network is managed by a DNO (Distribution Network Operator). That’s the company responsible for the cables and equipment in your area.
The DNO rules decide whether your system can be installed and then “notified”, or whether it needs permission first.
G98 vs G99 (simple explanation)
- G98 = smaller systems. Usually “fit it, then tell the DNO”.
- G99 = larger systems (or higher export). Usually “ask the DNO first”.
A common single-phase export threshold is 3.68kW (16A per phase). This figure is referenced in DNO distributed generation guidance. (SP Energy Networks (DG guide))
Plain English: you can install more than 3.68kW of panels, but if your system could export above 3.68kW, you’ll usually need DNO approval (or an agreed export limit) depending on how the system is designed.
We handle the DNO application as part of the design process, so you’re not left trying to decode forms and acronyms.
What is “inverter oversizing”?
This is when you install more panel power than the inverter rating (for example, 6kW of panels with a 5kW inverter).
In the UK, this can be useful because it helps you generate more electricity on grey days and in winter. On rare peak sunny moments, the inverter may “cap” output (that’s normal).
Is 10kW enough to run a house?
This question often mixes up two similar-looking units:
- kW = power right now (like speed)
- kWh = energy over time (what you’re billed for)
A 10kW solar system can generate a lot of electricity, but it won’t cover everything automatically because solar mainly generates during the day. If most of your usage is in the evening (cooking, showers, TV, tumble drying), you may still buy a lot of electricity from the grid at night.
That’s why many people pair solar with battery storage — it helps you use your solar energy after dark.
Store energy for later with home battery storage
Other ways to improve EPC ratings cheaply
Before spending on solar, it’s worth checking the basics — because EPC assessors look for these and they’re often quick wins.
Loft insulation
If you have a loft, insulation is often one of the best value improvements. A commonly referenced “good level” is around 270mm (where suitable).
LED lighting
Switching to LED lighting is usually cheap and helps the EPC because it’s an easy efficiency upgrade.
Does a smart meter improve EPC?
No. A smart meter helps you track usage, but it doesn’t improve the building’s efficiency in the EPC calculation. SAP states that having a smart meter does not change the SAP results. (SAP 10.2 (BRE) PDF)
Frequently asked questions
Does having solar panels make it harder to sell a house?
Usually, no. If the panels are owned outright, many buyers see them as a benefit.
Where it can get awkward is older “rent-a-roof” / leased panel arrangements, because they can add legal and lender checks. Standard ownership is generally much simpler.
RICS has published research showing a small price premium (in their analysis, around 0.9% to 2%) for homes with solar PV. (RICS)
Why is my electricity bill still high when I have solar panels?
The most common reasons are:
- you use most electricity in the evening (when solar isn’t generating)
- your system is too small for your usage
- you’re not using much power during the day, so you don’t benefit from “self-consumption”
Often the biggest improvement comes from using more electricity in daylight hours where possible, and/or adding battery storage.
Will triple glazing improve EPC?
It can help, but it’s often expensive compared with other improvements. For many homes, you get better EPC gains per pound spent from insulation, lighting upgrades, heating controls, or solar PV. Triple glazing can still be worthwhile for comfort and noise reduction.
How can Spartek can help
Solar PV can be one of the most effective ways to improve an EPC because it reduces the “assumed” grid electricity use in the SAP model. For many landlords and homeowners aiming to move up a band (for example, D to C), it can be a strong option especially when the basics are already in place.
If you want a system designed to suit your home, maximise savings, and handle the UK export/DNO rules properly, we can help.
Also worth reading: Why MCS certification matters
