Solar panels are often the poster child for eco-friendly upgrades—but when it comes to EPC (Energy Performance Certificate) scores, the reality is more complex.

Many homeowners install solar PV systems expecting their property to leap from a D to a B rating, only to find the EPC barely budges. Others add battery storage, only to realise it doesn’t influence the EPC at all.

So what’s really going on?

Let’s break down exactly what EPC assessors measure, why solar panels help less than expected, and where batteries fit into the equation (or don’t).

1. The EPC Measures Energy Efficiency, Not Sustainability

This is the root misunderstanding. EPCs are based on the SAP (Standard Assessment Procedure)—a modelling system designed to rate how efficiently a building uses energy under standard conditions.

That means:

  • EPCs measure energy demand, not carbon offset

  • The score reflects how much energy the home needs to heat, cool, and light, not how you generate or store it

🔍 A solar system might make your bills cheaper, but unless it reduces demand, it won’t massively shift the EPC.

2. What EPCs Do Consider About Solar Panels

Solar PV panels can improve your EPC score—but within strict limitations.

The EPC will consider:

  • Total peak output (kWp) of your solar array

  • Orientation and pitch of the panels (south-facing = best)

  • Whether energy is being exported or consumed onsite

But here’s the kicker:

👉 Solar panels only affect the electricity generation aspect of the EPC—not the heating, which typically weighs more heavily.

If your home still uses:

  • An old gas boiler

  • Electric panel heaters

  • Poor insulation
    —then your EPC score won’t climb much, regardless of how many panels you add.

3. Why Battery Storage Doesn’t Count in EPC Ratings (Yet)

One of the most frustrating aspects for green-minded homeowners:
Battery storage is completely ignored in the EPC assessment.

  • EPCs don’t account for when energy is used—only how much is required.

  • Whether your solar energy is stored or exported doesn’t change the calculated efficiency.

  • EPC models don’t yet include time-of-use optimisation or grid relief via batteries.

🧠 Even a cutting-edge Tesla Powerwall won’t impact your EPC rating—because the SAP methodology doesn’t model storage benefits.

4. Where Solar Does Shine in the EPC

While its influence is limited, solar power can still give a noticeable EPC bump if:

  • You combine it with high-efficiency heating (like air-source heat pumps)

  • The home has LED lighting, solid insulation, and good airtightness

  • The solar system is large enough and properly angled

📈 In some cases, solar PV can move a home from a low C to a high B—but only if other systems are already efficient.

5. How to Maximise EPC Impact with Renewables

If your goal is a better EPC (not just lower bills), combine solar with:

✅ Loft and cavity wall insulation
✅ Low-temperature heating systems (like ASHPs or underfloor heating)
✅ Smart heating controls
✅ Energy-efficient windows and doors

Solar alone won’t carry the EPC weight. But as part of a whole-house strategy, it helps tip the balance.

Final Word: Solar Panels Are Valuable—But EPCs Play by Old Rules

The EPC system has yet to catch up with modern home tech. Solar panels do help—but only partially. Batteries? Still invisible to the system.

Until EPC modelling evolves, homeowners should focus on core energy efficiency upgrades—and view renewables as a supporting role, not the lead.

The EPC graph is just the beginning. When you know how to read between the lines, your report becomes more than a score—it becomes a blueprint for saving energy, reducing emissions, and increasing property value.

Ready to unlock the full story of your EPC?
📅 Book your expert EPC assessment today at EPCrate.co.uk.