In Ireland, solar panels produce the most electricity facing due south at a tilt of 30–40°. That's the benchmark. But a south roof isn't the only good answer: east or west-facing panels still generate around 80–85% of a south roof's output, and an east-west split often matches your actual electricity use better than south does. The only direction genuinely worth avoiding is north.
Output by Direction (Compared to South)
Using solar irradiance data for Irish latitudes, here's roughly how much each orientation produces relative to a due-south roof:
| Roof faces | Output vs south | Verdict |
|---|---|---|
| South | 100% (benchmark) | Best for total annual output |
| South-east / south-west | ~90–95% | Excellent — barely any loss |
| East / west | ~80–85% | Still very worthwhile |
| North | Significantly lower | Avoid — not worth it |
The headline most people miss: the gap between the best roof and a "wrong" east or west roof is only about 15–20%. On a system generating, say, 3,500 kWh a year facing south, an east or west roof would still make around 2,900–3,000 kWh. That's not a reason to skip solar — it's a reason to size the system slightly larger if the budget allows.
The Best Tilt Angle: 30–40°
Direction is only half of it — the angle the panels sit at matters too. For Ireland, the optimal tilt is 30 to 40 degrees from horizontal; SEAI points to 35–40° on a typical roof as the sweet spot. The good news is that most Irish pitched roofs already sit somewhere in the 30–45° range, so panels mounted flush to the roof are usually close to ideal without any extra framing. Flat roofs are the exception: there, panels are mounted on angled frames to bring them up to the right tilt.
East-West Isn't the Compromise It Sounds Like
A south-facing array produces a tall, narrow generation curve — it peaks hard around midday and tails off either side. An east-west split does the opposite: panels on the east side catch the morning sun, panels on the west catch the evening, and you get a flatter, wider curve that starts earlier and runs later into the day. In an Irish summer with 16–17 hours of daylight, that's a long, useful generation window.
Why does that matter? Because most homes use the most electricity in the morning and the evening — not at midday when a south array is at full tilt and nobody's home. An east-west layout that lines up with when you actually use power means you self-consume more of what you make.
A unit of solar you use yourself saves you the day rate you'd otherwise pay — typically around 30–35 cent. A unit you export earns the Clean Export Guarantee rate, which is lower (roughly 18–25 cent depending on supplier). So electricity you use is worth more than electricity you sell. An east-west system that self-consumes 10–15% more than a south one can come out ahead financially, even though it generates a little less overall.
South-East or South-West?
The difference is small — both land in the 90–95% range. If you're choosing, south-west has a slight edge for most households because it pushes generation later into the afternoon and evening, when people are home and using power (and when the grid, and your self-consumption, value it most). South-east favours earlier generation. Unless you're out all evening and home all morning, south-west usually wins on a points decision.
What About North-Facing?
Avoid it. A north-facing roof loses enough output that the economics rarely stack up. If your only unshaded roof space faces north, the better moves are to use an east or west face instead, split across two faces, or look at a smaller plug-in setup rather than a full north-facing array.
How to Check Your Own Roof
These figures are rules of thumb. Your actual numbers depend on your exact roof angle, any shading from chimneys, trees or neighbouring buildings, and your county's irradiance. The EU's free PVGIS calculator lets you drop a pin on your house and model any orientation and tilt. For the version that matters — output matched against your real electricity demand, with shading accounted for — an SEAI-registered installer's site survey is the reliable answer.
That's exactly what a site survey is for. Solar Quotes Ireland matches you with SEAI-registered installers in your county who assess your roof's direction, pitch and shading, then quote a system sized to your home. Compare quotes with no obligation.
Get free solar quotes →Frequently Asked Questions
Due south at a tilt of 30–40 degrees produces the most electricity over a year in Ireland. South-east and south-west are nearly as good (about 90–95% of south), and east or west still produce around 80–85%. Only north-facing roofs are best avoided.
Yes. East or west-facing panels generate roughly 80–85% of what a south-facing roof would. They also spread generation across the morning and evening, when most homes use the most electricity — so you often self-consume more, which can make them better value than a south array despite the lower total output.
Between 30 and 40 degrees from horizontal, with SEAI pointing to 35–40 degrees on a typical roof as ideal. Most pitched Irish roofs already sit in this range, so flush-mounted panels are usually close to optimal. Flat roofs use angled frames to reach the right tilt.
Both are excellent, at around 90–95% of a south-facing roof. South-west has a slight edge for most households because it shifts generation into the afternoon and evening, when people are home and using power. South-east favours morning generation.
They generate electricity, but a north-facing roof loses enough output that the economics rarely make sense. If your only space faces north, an east or west face, an east-west split, or a smaller plug-in system is usually a better option.
For energy output, no — the orientation that matters is the compass direction the roof faces and its tilt, not whether panels are laid landscape or portrait. Layout is chosen to fit the roof shape and avoid shading, and has a negligible effect on annual generation.
Published: 5 June 2026. Author: Neil Russell. Orientation and tilt figures based on solar irradiance data for Irish latitudes (EU PVGIS) and SEAI guidance on optimal tilt. Export vs retail rate comparison: retail day rates per current Irish supplier tariffs; export rates per our Clean Export Guarantee rates page.