Heat pump payback
Grant, fuel bill, and a 15-year line
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Net cost after an SEAI grant, against your current fuel.
Payback
Payback here is the net cost (after the grant) divided by this year’s saving. A price rise on the chart does not change that figure.
Bills and the worked sum
Fuel bought = 18,000 ÷ 0.70 ÷ 10.18 = 2,526.0 litres.
Heat-pump electricity = 18,000 ÷ 3.00 = 6,000.0 kWh.
15-year schedule
| Year | Annual saving | Cumulative saving | Cumulative cash |
|---|---|---|---|
| 0 | €0.00 | €0.00 | -€10,500.00 |
| 1 | €2,031.60 | €2,031.60 | -€8,468.40 |
| 2 | €2,031.60 | €4,063.20 | -€6,436.80 |
| 3 | €2,031.60 | €6,094.80 | -€4,405.20 |
| 4 | €2,031.60 | €8,126.40 | -€2,373.60 |
| 5 | €2,031.60 | €10,157.99 | -€342.01 |
| 6 | €2,031.60 | €12,189.59 | €1,689.59 |
| 7 | €2,031.60 | €14,221.19 | €3,721.19 |
| 8 | €2,031.60 | €16,252.79 | €5,752.79 |
| 9 | €2,031.60 | €18,284.39 | €7,784.39 |
| 10 | €2,031.60 | €20,315.99 | €9,815.99 |
| 11 | €2,031.60 | €22,347.59 | €11,847.59 |
| 12 | €2,031.60 | €24,379.19 | €13,879.19 |
| 13 | €2,031.60 | €26,410.78 | €15,910.78 |
| 14 | €2,031.60 | €28,442.38 | €17,942.38 |
| 15 | €2,031.60 | €30,473.98 | €19,973.98 |
Where the grant figures come from
Where the grant figures come from
Checked on 2 November 2026 against the SEAI heat pump system grant page. For a house, the published maximum of €14,500 is described there as up to €10,500 for the heat pump, up to €2,000 for central-heating changes, and €2,000 boiler scrappage. Apartments are lower in the table (€11,500 for the water-based systems). Air-to-air is €9,500 for every dwelling type. Replacing a heat pump that was never grant-aided is €6,500, or €4,500 in an apartment, with no scrappage and no central-heating top-up. A separate €200 technical assessment grant is not included unless you add it to the install cost. You cannot be paid more than the works cost.
Fuel prices and gross calorific values are from the SEAI Domestic Fuel Cost Comparison dated 1 October 2026, also checked on 2 November 2026. Gas and electricity in that table are the EU survey for January to June 2026, not a live tariff. Standing charges are excluded. The electricity prefill is band DD, 33.92 cent/kWh, because SEAI says most homes with a heat pump are in that band.
Assumptions and references
Assumptions
- Useful heat is what the house and hot water actually need. Fuel bought is that heat divided by the seasonal efficiency, then by the gross kWh in each unit of fuel.
- Heat-pump electricity is useful heat divided by SCOP. SCOP and SPF are both “heat out divided by electricity in” over a season. Use the figure from the product sheet or from a measured season, not the example 3.0.
- SEAI’s calorific values are gross. An efficiency quoted on a net basis will not line up perfectly. Standing charges, servicing, and the €200 technical assessment are excluded unless you put them in the install cost.
- The grant used in the net cost cannot exceed the install cost, because SEAI will not pay more than the works.
- Simple payback is net cost divided by the year-1 saving. It ignores inflation, loan interest, maintenance, and how prices move. The chart can apply one optional annual rise to both bills. The payback number does not use that rise.
- Last checked 2 November 2026. Grants and prices change. This is not an energy assessment or a grant offer.
How this is calculated
- Net cost = install cost − grant, with the grant capped at the install cost.
- Current annual cost = (heat ÷ efficiency ÷ kWh per unit) × price per unit.
- Heat-pump annual cost = (heat ÷ SCOP) × electricity rate.
- Annual saving = current cost − heat-pump cost. Simple payback = net cost ÷ annual saving.
- Year 0 on the chart is minus the net cost. Each later year adds that year’s bill saving.