Upgrade · Use · your power · BER file 26 Sep 2026 · checked 8 Sep 2026
Solar panels are on 47% of older A- and B-rated houses, and 10% of the rest
Solar panels make electricity out of daylight. They're on 47% of older houses rated A or B and 10% of those rated C to E (SEAI BER file, 26 Sep 2026). In the typical home they move a rating 60.7 points, second only to a heat pump. SEAI's typical price for a semi-detached house is €9,500 and the grant pays €1,800.
Solar panels on a tiled roof under grey cloud. They make power from daylight, not only from sun.
A roof with solar panels on it · Budget Bizar · Pexels License
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47%
Older A- and B-rated houses with solar panels. Rated C to E: 10%
Solar PV · built before 2011 · BER file 26 Sep 2026
BER assessment60.7
Points on the BER scale it adds, for the typical home it applies to
kWh/m²/yr · research lane, BER file 26 Sep 2026
Our model1.5%
Homes sold or let with solar panels
BER file 26 Sep 2026
BER assessment19%
Of SEAI's typical semi-D price paid by the grant
€1,800 of €9,500 · SEAI H1 2026
Published figureUpdated · grants checked · BER file · prices SEAI H1 2026 · How we know · Corrections
Where this sits · the heat chain
A BER is a standard calculation across all four stages. Your bills also depend on how you live.
- Fabricwalls, roof, floor, windows
- Airdraughts and ventilation
- Heatheat pump or boiler, radiators, controls
- Usebills, comfort, the BER
- The idea behind itA BER is a standard calculation
- You are hereSolar panels
- Next questionHow much does SEAI pay towards solar panels?
Older A- and B-rated houses are 5 times as likely to have solar panels
What older houses rated A or B have, against those rated C to E. BER assessment
47% of older A- and B-rated houses have solar panels; 10% of those rated C to E
The biggest gap is insulated walls: 63% against 25%.
- Insulated walls. Rated A or B: 63%. Rated C to E: 25%.
- Solar panels. Rated A or B: 47%. Rated C to E: 10%.
- An insulated floor. Rated A or B: 74%. Rated C to E: 40%.
- Attic at the grant standard. Rated A or B: 33%. Rated C to E: 19%.
- High-performance windows. Rated A or B: 26%. Rated C to E: 3.8%.
- A heat pump. Rated A or B: 21%. Rated C to E: 0.2%.
- Solar water heating. Rated A or B: 7.8%. Rated C to E: 2.2%.
- Mechanical ventilation. Rated A or B: 7.2%. Rated C to E: 0.9%.
Each pair of bars is the share of houses built before 2011 that have the upgrade, among those rated A or B (dark) and those rated C to E (grey), from every certificate issued 2019-2026. Solar panels: 46.9% against 9.7%. It shows what the better-rated houses have, not proof of what got them there: newer houses are more often A or B and were built with some of these.
Sources: SEAI BER Research Tool, every existing-home certificate 2019–26 for houses built before 2011 (440,689 certificates), 26 Sep 2026 · Insulated walls: Walls U ≤ 0.37 · Solar panels: Solar PV · An insulated floor: Floor U ≤ 0.45 · Attic at the grant standard: Roof U ≤ 0.16 · High-performance windows: Windows U ≤ 1.6 · A heat pump: Heat pump · Solar water heating: Solar water · Mechanical ventilation: Mechanical ventilation
The numbers
| Upgrade | Rated A or B | Rated C to E |
|---|---|---|
| Insulated walls | 62.8% | 25.4% |
| Solar panels | 46.9% | 9.7% |
| An insulated floor | 73.6% | 39.9% |
| Attic at the grant standard | 33.3% | 19.3% |
| High-performance windows | 26.1% | 3.8% |
| A heat pump | 20.9% | 0.2% |
| Solar water heating | 7.8% | 2.2% |
| Mechanical ventilation | 7.2% | 0.9% |
On its own, solar panels moves a rating 60.7 points; a heat pump, 93
What one job on its own does to the typical home's rating, where the job applies. One letter on the new scale is 50 points. Our model
Solar panels: 60.7 points on its own, where it applies
Where the job applies, the median gain is 93 kilowatt-hours per square metre a year for a heat pump, 60.7 for solar panels, 46.7 for wall insulation and 10.4 for new windows. One letter on the new scale is 50.
Each bar is the median improvement to a home's BER from that one job on its own, among homes sold or let where the job applies, worked out on each certificate's own figures. A heat pump moves the rating nearly two letters in the D to F range; attic insulation, draught-stripping and blocking chimneys barely move the rating on their own. The bracket shows one letter's width (50, for D, E and F). The bars are not additive.
EstimateOur model: the research lane's one-job recalculation on each certificate's own figures (BER file of 26 Sep 2026, not the site's 8 Sep file). It matches SEAI’s published heat loss to a median ratio of 1.00 and uses the electricity factor in force on each certificate’s date.
Sources: fixmyber research lane, research/ber/s4_thresholds.py, 26 Sep 2026
The numbers
| Job | Median gain, kWh per m² a year |
|---|---|
| Heat pump | 93 |
| Solar panels | 60.7 |
| Wall insulation | 46.7 |
| New windows | 10.4 |
| Attic insulation | 6.1 |
| Blocking chimneys | 2.4 |
| Draught-stripping | 0.4 |
What solar panels do on an Irish roof
Solar panels make electricity out of daylight. They work under Irish cloud, just not as hard as they do on a clear day in June.
What goes on the roof
Panels on the roof, an inverter on a wall inside, and a day's work. There is nothing to maintain, nothing to feed and nothing to hear. A kilowatt of panels is three or four of them, and a typical house takes three or four kilowatts.
The panels make direct current when light falls on them; the inverter turns that into the kind of electricity the sockets use. Whatever the house is using at that moment is served first. Whatever is left goes out to the grid.
That last sentence is the whole design problem. Panels produce at midday. Houses use power at eight in the morning and seven in the evening. Everything you can do to move usage into the middle of the day — the immersion, the washing machine, an electric car, a heat pump running its hot water cycle — turns exported units into units you didn't have to buy.
Panels on a house roof rarely need planning permission: the conditions, in the law's words.
Compared with buying every unit from the grid
| Grid electricity | Your own panels | |
|---|---|---|
| What a unit costs | 34.4c for direct electric heat | nothing, once the system is paid for |
| When you get it | any time | daylight, mostly the middle of the day |
| Across the year | flat | about 75% of it between May and September |
| In cloud | unaffected | still generating, below rated output |
| What it does to the bill | — | cuts the units you buy, if you use them as they're made |
| Kit that wears out | none of yours | the inverter, before the panels |
| Time to fit | — | about a day, no rooms cleared |
Grant €700 per kWp to 2 kWp, then €200 per kWp to 4 kWp, capped at €1,800; paid pro rata, e.g. €1,500 for a 2.5 kWp system. SEAI median cost €9,500 for a semi-detached, €11,100 detached. Home must have an MPRN and have been built and occupied before 2021 (before 2025 from 6 October 2026); not available where PV was previously grant-aided at the same MPRN; 8 months from grant offer to completion. Grant steps and conditions read on seai.ie 8 September 2026; cap amount verified 2026-10-03.
Where the saving comes from
Every other upgrade on this site reduces the heat a house loses. Solar panels don't touch the heat at all — they cut the number of units you buy. That's a different kind of saving, and it behaves differently: it doesn't depend on how cold the winter is, it doesn't care how good the walls are, and it is worth exactly what a unit of electricity costs on the day you don't buy it.
It's also why panels and a heat pump suit each other. A heat pump turns the house's heating bill into an electricity bill, and panels take a bite out of electricity bills. Heat from a heat pump costs about 9.8c a unit against 34.4c for plug-in electric heat; the panels then chip away at what's left.
A 1970s–80s detached house on oil, rated C — for the 24,045 homes in that group the cheapest grant-eligible route to a B includes solar panels, and it repays in about 13 years at the modelled saving. That is slower than the insulation measures, because the grant covers a smaller share of the cost. detached|1970-1989|C|oil: cost p50 €19,700, grant €14,500, you pay p25–p75 €4,100–€13,688, saving €781/yr, payback 5.5–17.2 yrs, n=24,045, confidence 0.6
Questions people ask
- Does solar work in Irish weather?
- Yes. Panels run on daylight, not warmth, so cloud reduces the output rather than stopping it — SEAI say a system still works on an overcast day, below its rated output. The real constraint is the season. About 75% of the year's generation happens between May and September, so the panels give least in the months you use most.
- How much of my electricity will it cover?
- SEAI's worked example is a system of about 20 square metres, roughly 3 kilowatts, generating around 2,600 units a year — over 40% of what an average Irish home uses. Covering that much of the bill is a different matter, because the panels make their power in the middle of the day and most houses use theirs in the evening.
- Do I need planning permission?
- Usually not, if the panels stay 50 cm in from the edge of the roof and don't go forward of the front wall of the house. Panels on a wall are not exempt, free-standing panels in the garden have their own size limits, and a house in an architectural conservation area needs a call to the council first.
How we know
- Ratings: From SEAI's BER Research Tool (files of 8 Sep 2026 and 26 Sep 2026): certificates for homes sold or let, and every certificate for houses built before 2011. A BER is a standard calculation, not a meter reading.
- One job at a time: Our model reworks each certificate with one job done, on the BER file of 26 Sep 2026. Its heat loss matches SEAI's own figure to a median ratio of 1.00. A group figure, not an assessment of your house.
- Grants and prices: SEAI's grant pages, read on the dates shown, and SEAI's median costs of individual upgrades for 2025. A median is a middle price, not a quote.
Sources
seai.ie · electricity from solar · seai.ie · solar electricity grant · seai.ie · Median costs of individual energy upgrades
Found a mistake? Every fix is dated on Corrections. Method in full: How we know.
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Updated · grants checked · BER file · prices SEAI H1 2026 · How we know · Corrections