How much of my hot water will it cover?

SEAI put it at 50 to 60% of a year's hot water on the grant page, and up to 60% over twelve months on their technology page. Both of those are annual figures and they hide a big swing — close to all of it on a bright week in June, close to none of it in December, when you are back on the boiler or the immersion.

Flat plate or evacuated tubes?

Flat plate collectors are cheaper and can be set into the roof as well as onto it. Evacuated tubes cost more, only go on top of the roof, and give about 20% more hot water for each square metre — and SEAI say they do better in low light, which is worth something in an Irish winter.

Should I get this or solar panels?

They do different jobs, so it depends on what your house needs. Solar hot water only makes hot water, and it makes a lot of it in summer, when a house needs least. Solar panels make electricity you can use for anything, including sending the extra to the immersion. Most houses being upgraded today are being fitted with panels; the grant for hot water is there for the ones where hot water is the problem.

Upgrade · Heat · hot water · BER file 26 Sep 2026 · checked 8 Sep 2026

Solar water heating is on 7.8% of older A- and B-rated houses, and 2.2% of the rest

Solar hot water collectors heat water directly. It's on 1.8% of homes sold or let (SEAI BER file, 26 Sep 2026), and 7.8% of older houses rated A or B. The grant is €1,200, the same for every home. SEAI publishes no typical price for the job, so we can't say what share it covers.

Five evacuated-tube solar water-heating panels in a row on the concrete-tiled roof of a pebble-dashed semi-detached house. — Tube collectors for solar water heating on the roof of a semi-detached house in south Dublin.
Solar Hot Water Panels On Suburban House Roof South Dublin Sep2012 · Terence wiki · CC BY-SA 3.0

See your grants and what you’d pay

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€1,200

The grant, the same for every type of home

SEAI solar water heating · read 3 Oct 2026

SEAI rule

1.8%

Homes sold or let with solar water heating

BER file 26 Sep 2026

BER assessment

7.8%

Older A- and B-rated houses with solar water heating. Rated C to E: 2.2%

Solar water · built before 2011 · BER file 26 Sep 2026

BER assessment

Updated 5 October 2026 · grants checked 10 Oct 2026 · BER file 8 Sep 2026 · prices SEAI H1 2026 · How we know · Corrections

Where this sits · the heat chain

The heating only puts back what the house loses. A heat pump works best when the house loses less.

Fabricwalls, roof, floor, windows
Airdraughts and ventilation
Heatheat pump or boiler, radiators, controls
Usebills, comfort, the BER

The idea behind itFabric first: the heat-loss line
You are hereSolar hot water
Next questionHow much does SEAI pay towards solar water heating?

Older A- and B-rated houses are 4 times as likely to have solar water heating

What older houses rated A or B have, against those rated C to E. BER assessment

Figure 1BER assessment

7.8% of older A- and B-rated houses have solar water heating; 2.2% 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 water heating: 7.8% against 2.2%. 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

The numbers behind figure 1
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%

What solar hot water is, and how it differs from solar panels

Solar hot water collectors heat water directly. They are plumbed into the cylinder, not wired into the fuse board, and they cover about half a year's hot water.

What goes in

Two or three collectors on the roof, a pump, and a coil in the hot water cylinder. Fluid runs up to the collectors, warms, comes back down and gives its heat to the water in the cylinder. On a good day the boiler never comes on and the immersion is never touched.

There are two kinds. Flat plate collectors are a sealed box with an absorber inside; they are the cheaper option and can sit in the roof or on it. Evacuated tubes are rows of glass tubes on a frame, they only go on the roof, they cost more, and per square metre they deliver about a fifth more hot water. SEAI also say the tubes hold up better in low light, which matters more here than it would further south.

There is no SEAI median cost for this work, so this site does not publish a price for it. Get two or three quotes.

Compared with the ways you heat water now

	Immersion heater	Gas or oil boiler	Solar hot water
What it runs on	electricity at full price	the same fuel as your heating	daylight
In June	expensive, and it heats nothing else	fires the whole boiler for one tank	most of the tank, free
In December	works, at a price	works	little, and you're back on the boiler
Across a year	all of your hot water	all of your hot water	50 to 60% of it, SEAI say
What breaks	the element	the boiler	the pump, before the collectors
Grant	none	none	€1,200

Grant €1,200 regardless of property type; home must have an MPRN and have been built and occupied before 2021 (before 2025 from 6 October 2026). SEAI: systems are "designed to meet 50-60% of your annual hot water needs"; evacuated tubes give ≈20% more hot water per m² of aperture than flat plate. Read on seai.ie 8 September 2026. Amounts verified 2026-10-03.

Where the saving comes from

Hot water is a fixed cost in a way heating isn't. A well-insulated house needs less heat every year, but it needs the same number of showers. So the cylinder is one of the few places where the saving doesn't shrink as the rest of the house improves.

The catch is the shape of the year. The sun is generous in the months a house needs least and mean in the months it needs most, and no collector fixes that. That is why the honest figure is an annual one — about half — and why the boiler or the immersion stays in the house as backup.

No published cell on this site has solar hot water in its cheapest grant-eligible route to a B, so there is no modelled cost, saving or repayment time for it here — the model reaches the target more cheaply by other means. SEAI publish no median cost for solar thermal either; the €9,500 median shown for solar panels on a semi is for photovoltaics, a different technology.

What the grant pays, by type of home

Questions people ask

How much of my hot water will it cover?: SEAI put it at 50 to 60% of a year's hot water on the grant page, and up to 60% over twelve months on their technology page. Both of those are annual figures and they hide a big swing — close to all of it on a bright week in June, close to none of it in December, when you are back on the boiler or the immersion.
Flat plate or evacuated tubes?: Flat plate collectors are cheaper and can be set into the roof as well as onto it. Evacuated tubes cost more, only go on top of the roof, and give about 20% more hot water for each square metre — and SEAI say they do better in low light, which is worth something in an Irish winter.
Should I get this or solar panels?: They do different jobs, so it depends on what your house needs. Solar hot water only makes hot water, and it makes a lot of it in summer, when a house needs least. Solar panels make electricity you can use for anything, including sending the extra to the immersion. Most houses being upgraded today are being fitted with panels; the grant for hot water is there for the ones where hot water is the problem.

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 · solar water heating grant · seai.ie · hot water from solar · seai.ie · electricity from solar

Found a mistake? Every fix is dated on Corrections. Method in full: How we know.

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Updated 5 October 2026 · grants checked 10 Oct 2026 · BER file 8 Sep 2026 · prices SEAI H1 2026 · How we know · Corrections