“Is solar worth it?” has no single answer for Ireland — but it has a clear method. Four numbers decide most of it: the price after the grant, how much of the output you use yourself, your import rate, and your export rate. This guide works through an example with visible assumptions and shows how far each number moves the result, so you can judge your own quote.
First, the weather myth
Panels generate from daylight, not heat or direct sun, so they still produce on grey days — just less. What matters is the annual total. A rough guide in Ireland is 900–1,000 kWh a year for each kWp installed, with long summer days doing much of the work and winter output low. That seasonal shape matters: in winter almost everything is used in the home; in summer much more is exported.
A worked example
Hypothetical figures, matching the default example in our calculator:
| Assumption | Value |
|---|---|
| Quote before grant | €9,000 for 4 kWp |
| SEAI grant | €1,800 → net cost €7,200 |
| Annual generation | 3,600 kWh |
| Used directly in the home | 40% → 1,440 kWh |
| Import rate avoided | 30c per kWh |
| Export rate | 15c per kWh |
| Maintenance allowance | €100 a year |
- Annual benefit = 1,440 × €0.30 + 2,160 × €0.15 − €100 = €432 + €324 − €100 = €656
- Simple payback = €7,200 ÷ €656 ≈ 11 years
What moves the answer
Change one assumption at a time from the example above:
| Change | Annual benefit | Simple payback |
|---|---|---|
| Self-use 30% instead of 40% | €602 | ~12.0 years |
| Self-use 50% | €710 | ~10.1 years |
| Self-use 60% | €764 | ~9.4 years |
| Self-use 70% | €818 | ~8.8 years |
| Export rate 10c instead of 15c | €548 | ~13.1 years |
| Export rate 20c | €764 | ~9.4 years |
| Import rate 40c instead of 30c | €800 | ~9.0 years |
| Net cost €6,200 instead of €7,200 | €656 | ~9.5 years |
The pattern is clear: self-use and price matter most. Each extra unit you use at home is worth your full import rate; each unit you export earns less. Simple payback also leaves out financing, panel degradation, inverter replacement and future price changes — treat it as a comparison tool, not a promise.
How to raise your self-use
- Run the dishwasher, washing machine and dryer during daylight, using delay timers.
- Charge an EV during the day when you can.
- Divert surplus to hot water — compare the value in export or hot water?
- Consider a battery only after checking the numbers in is a solar battery worth it?
A quick fit check
| Factor | Good fit | Weaker fit |
|---|---|---|
| Roof | South, east or west; little shading | North-only or heavily shaded |
| Daytime use | Someone home, or loads can be shifted | Empty all day, nothing can move |
| Annual use | Average or above | Very low |
| Plans | Staying well beyond payback | Likely to move within a few years |
| Home | Reasonably insulated | Cold and draughty |
If most of your answers fall in the right-hand column, solar may still work, but it probably isn’t the best first upgrade — insulation or heating may deliver more comfort per euro. See the insulation guide.
What lowers your real cost
- The SEAI grant of up to €1,800 — see the grant guide
- 0% VAT on the supply and installation of panels on homes
- Export payments under the Clean Export Guarantee — see selling electricity back to the grid
For price ranges by system size, see solar panel cost in Ireland, and compare installers like for like with our quote checklist.
