Adding solar panels usually improves your BER rating, because the electricity they generate reduces the primary energy and carbon emissions the assessment counts against your home. But the rules for calculating BERs in Ireland changed in May 2026, and solar now counts for somewhat less than it did. This guide explains how PV affects a BER, what changed in 2026, and why the grant process makes a post-works BER part of every SEAI-funded solar installation. Checked against SEAI and other sources on 26 October 2026.
How solar panels affect your BER rating
A BER (Building Energy Rating) estimates how much primary energy a home needs per square metre per year for standard heating, hot water, ventilation and lighting, using SEAI’s DEAP methodology. It is a calculated rating based on the building, not your actual bills. Solar PV feeds into that calculation as on-site renewable electricity: the assessor records the system and DEAP credits the electricity it’s expected to produce against the home’s energy use.
In broad terms, the effect depends on:
- The size of the system in kWp
- The roof orientation, pitch and any overshading
- The size of the home: the same system makes a bigger difference per m² in a smaller house
- What else the home uses: insulation, heating system and hot water
- Under the 2026 rules, whether a battery is fitted
Because so many factors interact, we can’t give a reliable “solar adds X grades” figure, and you should be wary of anyone who does without assessing your home. A registered BER assessor can model a proposed system before you commit.
What changed in the 2026 BER rules
SEAI introduced a simplified BER scale on 24 May 2026, as part of Ireland’s implementation of the EU Energy Performance of Buildings Directive (SEAI):
- The scale moved from 15 grades to 8: A0, A, B, C, D, E, F and G, with no sub-grades such as B2 or C3.
- A0 is a new top category for buildings that don’t use fossil fuels.
- Existing certificates remain valid for 10 years from issue and still count for sale or rental, unless major renovations take place.
- New certificates show the renewable energy contribution and lifecycle (global warming potential) emissions as additional information.
SEAI’s DEAP guidance now states it applies to BERs for new and existing dwellings from 24 May 2026 and is laid out to replicate the DEAP v4.3 software (SEAI DEAP guide).
The methodology change that matters for solar
The Construction Industry Federation reported that the primary energy factor (PEF) for electricity was reduced at the same time, reflecting a cleaner grid (CIF, June 2026). West Cork People reported the factor fell from 1.75 to 1.5, and that “solar PV will have less impact on your overall BER result because it is now offsetting less penalised primary energy” (West Cork People, June 2026). The same article reports that the calculation now takes account of whether a battery is fitted, which previously had no effect on the BER.
We couldn’t find SEAI publishing the new electricity factor on a consumer-facing page, so treat the 1.5 figure as reported rather than confirmed, and ask your assessor which factors apply to your rating.
What A0 requires
The Housing Agency lists Ireland’s A0 definition as primary energy of 42kWh/m²/yr or less, carbon emissions of 5kg CO₂eq/m²/yr or less, no fossil fuels on site, the capacity to respond to external signals, and nZEB compliance (Housing Agency, 2026). For most existing homes, A0 needs a heat pump and strong insulation; solar PV helps but won’t get there alone.
Grades under the old and new scale
Because the bands changed, a home’s letter can shift without any work being done. West Cork People gave three examples of homes rated under both systems (source):
| Example home | Old scale | New scale |
|---|---|---|
| Heat pump, no solar PV | A2 | A0 |
| Oil boiler with solar PV | C3 | D |
| Heat pump with solar PV | A3 | B |
The point for solar buyers: if you’re comparing an old certificate with a new one, a lower-looking letter doesn’t necessarily mean the house got worse.
The post-works BER and the SEAI grant
If you claim SEAI’s solar grant, a BER is part of the process. SEAI’s application guide (V6.0, 12 October 2026) says you need a BER assessment by an SEAI-registered BER assessor after the installation is complete, published on the National BER Register, and that the installer and assessor must submit their paperwork before the 8-month grant offer expires (SEAI application guide). The guide notes assessors are in high demand, so book one once you have an installation date. A post-works BER isn’t needed for a battery-only grant where there is no solar PV at the property. Ask your installer or assessor what the BER will cost, as we couldn’t confirm in SEAI’s current guide whether it’s covered.
The BER also helps prove eligibility. From 6 October 2026, the grant is open to homes built and occupied before 2025 (SEAI application guide V6.0), and SEAI’s Code of Practice asks for the property’s year of construction with reference to the BER certificate (SEAI Code of Practice). The grant pays €700 per kWp up to 2kWp and €200 per extra kWp up to 4kWp (panels capped at €1,800), plus €600 for a 5kWh+ battery, up to €2,400. See our solar grants page.
Should you install solar mainly to improve your BER?
Usually not on its own. SEAI’s homeowner guide advises making sure your home has a good energy performance before investing in solar (SEAI), and with the lower electricity factor, insulation and heating upgrades now carry relatively more weight. Solar makes most sense when it also cuts your bills. Where a better BER matters, for example for a green mortgage, West Cork People reports that lenders are expected to use the new B band as the benchmark, though lenders are still updating their criteria.
If you’re thinking about resale, read do solar panels add value to your home in Ireland?. And because a battery now affects the calculation, it’s worth reading solar panels with a battery vs without.
Questions to ask your BER assessor
- What’s my current rating under the new scale?
- What would a 2kWp, 3kWp or 4kWp system do to it, with and without a battery?
- Would insulation, a heat pump or a hot water upgrade improve it more per euro?
- Which DEAP version and primary energy factors are you using?
FAQs
Will solar panels improve my BER?
Usually, yes, because DEAP credits on-site renewable electricity. The size of the improvement depends on the system, the house and its heating, and since May 2026 PV counts for somewhat less because the electricity primary energy factor was reduced.
Does a solar battery affect the BER?
According to West Cork People’s June 2026 report on the new rules, the calculation now accounts for whether a battery is fitted; previously it had no impact. Ask your assessor how it applies to your home.
Is my old BER certificate still valid?
Yes. SEAI says existing certificates remain valid for 10 years from their date of issue.
Do I need a BER for the solar grant?
Yes, for a solar PV grant. SEAI requires a post-works BER by a registered assessor before payment. A battery-only grant at a property without solar PV doesn’t need one.
What is an A0 BER?
The new top band for homes using no fossil fuels on site. The Housing Agency lists the threshold as 42kWh/m²/yr primary energy or less, with very low emissions.
Get your solar quote today
Get your solar quote today. Tell us about your home and we’ll connect you with SEAI-registered installers who can size a system for your roof and handle the grant paperwork, including the post-works BER. Or call 089 450 4544.
