Roof Suitability and Orientation for Solar Panels (2026)
Roof suitability for solar panels in Ireland, including orientation, pitch, shading, usable roof area, structural condition and expected generation impact.
Best performance: south-facing, 30°–40° pitch, minimal shading
What Makes a Roof Suitable?
Solar output depends heavily on orientation, roof pitch, available area, shading and structural condition.
South-facing roofs produce the highest output, but east–west roofs can still perform well and may better spread generation across the day.
Most Irish homes with enough usable roof area can support around 3–6 kWp of solar PV.
Orientation & Output
South: 100%
South-East / South-West: 90–95%
East / West: 80–90%
North-East / North-West: 60–75%
Pitch & Roof Area
Roof Pitch
15°–25°: 90–95% efficiency
30°–40°: 100% optimal range
45°–55°: 90–95%
Roof Area Needed
3 kWp: ~15 m²
4 kWp: ~19 m²
5 kWp: ~26 m²
6 kWp: ~34 m²
Shading & Structural Suitability
| Factor | Typical Impact |
|---|---|
| Minor shading | 5–10% output reduction |
| Moderate shading | 10–25% reduction |
| Heavy shading | 25%+ reduction |
| Typical panel-system load | 15–20 kg/m² incl. mounting hardware |
Roof repairs or re-roofing may be sensible before solar installation if tiles are damaged or the roof is nearing end-of-life.
Multiple Orientations & Flat Roofs
East–west split arrays can provide morning and afternoon generation and may match household demand better than a single south-facing array.
Flat roofs use ballasted frames or roof anchors, normally at around 10°–20° tilt.
Flat-roof rows need extra spacing to avoid one row shading another.
Generation Example by Orientation
| 4 kWp System Orientation | Approx. Annual Output |
|---|---|
| South-facing | ~4,200 kWh |
| East / West split | ~3,800 kWh |
| North-East | ~3,000 kWh |
Actual output still varies with pitch, shading and local weather conditions.
Planning, Obstacles & Suitability Checks
Roof Obstacles
Dormers, skylights, chimneys and satellite dishes reduce usable panel area
Panel layout should be designed around these features
Planning / Visual
Solar panels are usually permitted development
Protected structures, conservation areas and visible front-facing arrays may need extra consideration
Typical Outcome
Most suitable Irish roofs can support 3–6 kWp
Overall output may vary by up to 40% due to orientation and shading
Summary
Solar panels perform best on south-facing roofs at roughly 30°–40° with minimal shading.
East–west roofs can still deliver around 80–90% of south-facing output.
Usable roof area, structural condition and shading should be confirmed before choosing system size.
Other resources:
Solar Panel Cost After SEAI Grant
Solar Panel Battery Add-On Cost