East vs South vs West-Facing Roofs: Which Is Best for Solar?

Does Roof Orientation Really Matter?

One of the most common concerns homeowners have when considering solar is whether their roof faces the "right" direction. There is a persistent myth that only south-facing roofs are suitable for solar panels. The reality is far more nuanced - and far more encouraging. Modern solar panels are remarkably effective across a range of orientations, and a north-facing roof is actually the only orientation that is genuinely unsuitable in Ireland.

In Ireland, we are fortunate to be at a latitude (approximately 53°N) where the sun travels a wide arc across the sky during summer. This means that east, south, and west-facing roofs all receive substantial sunlight. The differences in output are meaningful but not dramatic, and the financial case for solar remains strong regardless of your roof's orientation.

South-Facing Roofs: The Gold Standard

A south-facing roof is undeniably the optimal orientation for solar panels in Ireland. Because Ireland is in the Northern Hemisphere, the sun arcs from east to west through the southern half of the sky. A south-facing roof therefore receives the most direct sunlight throughout the day, particularly during the peak generation hours of late morning to early afternoon.

• Annual output: 100% of rated system capacity
• Peak generation: 11am – 3pm (when the sun is highest in the sky)
• Best suited for: Households that are home during the day and can use electricity during peak generation hours
• Payback period: 5–6 years (fastest of all orientations)

East-Facing Roofs: The Morning Champions

East-facing roofs receive their strongest sunlight in the morning, from sunrise through to late morning. While they produce 15–20% less electricity overall than a south-facing roof, they have a unique advantage: their generation profile aligns perfectly with morning household routines.

Think about your morning routine: toast, kettle, shower, lights, phone charging, heating the house. An east-facing system peaks just when you are using the most electricity, meaning more of your solar generation is consumed directly rather than exported to the grid. Since using your own solar electricity is worth more than exporting it (you save €0.35–€0.45/kWh versus earning €0.20/kWh), this higher self-consumption rate partially offsets the lower total output.

• Annual output: 80–85% of rated capacity
• Peak generation: 8am – 12pm
• Best suited for: Households with high morning electricity consumption
• Payback period: 6–7 years

West-Facing Roofs: The Afternoon Powerhouse

West-facing roofs mirror east-facing ones, with peak generation occurring from mid-afternoon through to early evening. This makes them an excellent choice for households where people are out during the day and return in the late afternoon and evening.

In Ireland, many households follow a pattern where the house is largely empty during the day (people at work or school), and electricity usage peaks in the evening. A west-facing system generates maximum power exactly when you come home and start cooking, running appliances, and turning on lights. Like east-facing systems, this high self-consumption rate means the financial returns are better than the raw output figures suggest.

• Annual output: 80–85% of rated capacity
• Peak generation: 2pm – 6pm
• Best suited for: Households that are out during the day and home in the evening
• Payback period: 6–7 years

North-Facing Roofs: Worth It?

North-facing roofs receive the least direct sunlight in Ireland. A north-facing solar array will typically generate only 50–55% of a south-facing equivalent. For most homeowners, this is not an attractive proposition - the longer payback period (9–11 years) means the financial returns are significantly diminished.

However, there are exceptions. If you have a large roof area and can fit a bigger system on the north side for a low additional cost, or if your north roof is completely free from shading while your south roof is obstructed, a north-facing installation can still make financial sense. Some installers also offer mixed-orientation setups.

Split Arrays: The Best of Both Worlds

If your home has roof planes facing different directions, you may be able to install a split array - panels on both an east and a west roof, for example. Split arrays have become increasingly popular in Ireland because they offer a broader generation profile throughout the day.

Other Factors That Matter More Than Orientation

While roof orientation is important, several other factors have an equal or greater impact on your system's performance:

• Shading - Even a small amount of shading (chimney, tree, neighbouring building) can reduce output by 10–25%. Eliminating shading is more important than optimising orientation.
• Pitch angle - The ideal pitch for Ireland is approximately 35–40°. Most standard Irish roofs fall within 30–45°, which is excellent for solar.
• Roof condition - A roof that needs replacement within the next 5–10 years should be replaced before installing solar. Removing and reinstalling panels adds significant cost.
• System sizing - An oversized system on a west-facing roof may produce more usable energy than an undersized system on a south-facing roof.

The key takeaway is simple: if your roof faces east, south, or west, solar panels are a worthwhile investment in Ireland. The differences between these orientations are relatively modest in the context of a 25-year panel lifespan, and the financial case remains strong across all three.