South Facing Roof or East West Solar Array: Which Is Better for Scotland?

The conventional wisdom on solar orientation is that south facing is best. It is true. A south facing array at an optimum pitch generates more annual electricity than the same panels facing east, west, or split between the two. What the conventional wisdom often misses is that more annual generation does not necessarily mean more household financial benefit. For many Scottish homes, an east west split array delivers more useful electricity to the household even though it generates slightly less in total. This page sets out the comparison clearly so you can choose the right orientation for your specific situation.

The headline numbers

For a typical 4kWp residential array in Aberdeenshire, the annual generation differs by orientation as follows:

• South facing at 30 to 40 degree pitch: 100% reference output (approximately 2,600 kWh per year).
• South east or south west facing: 90% to 95% of south facing output.
• East or west facing: 75% to 85% of south facing output.
• East west split (half panels east, half panels west): approximately 80% to 88% of south facing output.
• North facing: 50% to 65% of south facing output. Generally not recommended.

So a south facing 4kWp system generates approximately 2,600 kWh per year while an east west split system at the same kWp generates approximately 2,200 to 2,300 kWh per year. The south facing system wins on raw generation by 300 to 400 kWh per year.

The interesting question is what happens to those generation totals once we look at when the electricity is generated and how much is actually used by the household.

When the electricity is generated matters

A south facing array generates a sharp peak in the middle of the day. Output rises through the morning, peaks around noon, and tails off through the afternoon. This is the classic solar generation curve.

An east west split array generates two smaller peaks: one in the late morning from the east facing panels and one in the afternoon from the west facing panels. The total daily generation is lower than the south facing equivalent, but it is spread across a longer period of the day. The morning peak from east facing panels happens at 9am to 11am. The afternoon peak from west facing panels happens at 2pm to 5pm.

For a household where a significant proportion of electricity demand is in the morning (showers, breakfast, getting ready for school and work) and in the late afternoon to early evening (dinner preparation, returning from school, evening activities), the east west generation profile aligns better with consumption than the south facing midday peak does.

The self consumption advantage

The key concept is self consumption: the proportion of generated electricity that is used directly within the home rather than exported to the grid at the lower SEG rate.

For a typical Aberdeenshire household without a battery and with normal working hours occupancy:

• South facing 4kWp array: 35% to 40% self consumption rate. The big midday peak overwhelms typical midday consumption, so much is exported.
• East west split 4kWp array: 45% to 55% self consumption rate. The morning and afternoon peaks align better with household consumption.

For the same household, the financial outcome:

South facing 4kWp (2,600 kWh annual generation):

• Self consumed at 24p: 1,000 kWh = £240 per year.
• Exported at 14.5p: 1,600 kWh = £232 per year.
• Total annual benefit: £472 per year.

East west split 4kWp (2,250 kWh annual generation):

• Self consumed at 24p: 1,150 kWh = £276 per year.
• Exported at 14.5p: 1,100 kWh = £159.50 per year.
• Total annual benefit: £436 per year.

The two are essentially equal in financial terms despite the south facing array generating 350 kWh more electricity per year. The south facing system loses the financial advantage of higher generation because more of that generation is sold at the export rate rather than consumed at the import rate.

When does south facing win?

South facing remains the better orientation in three situations:

• Battery storage: A battery captures surplus midday generation and releases it in the evening. With a battery, the south facing midday peak is no longer wasted: it charges the battery for evening use. The self consumption proportion rises to 65% to 80% regardless of orientation, and the south facing array’s higher total generation translates directly into more battery storage and more bill savings.
• Daytime occupied properties: Households with a working from home occupant, retired residents, or anyone who consumes substantial electricity during the middle of the day (running a heat pump during the day, scheduling the dishwasher and washing machine for midday) capture more of the south facing peak directly. Self consumption rises to 50% or more without a battery.
• EV charging during the day: If an EV is parked at home during the day and connected to a smart charger that diverts solar surplus, the midday peak from a south facing array goes to the car rather than to the grid. The south facing higher generation translates into more solar miles for the EV.

For these situations, south facing is clearly the better choice if a south facing roof is available.

When does east west win?

East west split arrays are the better choice in three situations:

• Working hours occupancy without battery: If both adults work during typical office hours, the household is empty during the south facing peak. Without a battery, this generation goes straight to the grid. The east west alignment captures the morning and late afternoon shoulders when the household is at home, getting ready, and starting evening activities.
• Properties without a south facing roof: Some Aberdeenshire properties simply do not have a south facing aspect. A house aligned east to west with pitches facing north and south makes sense, but many older Aberdeen properties are aligned north to south with pitches facing east and west. For these properties, the east west array is the available option, and it works well.
• Hipped roofs with limited south facing area: Many Aberdeenshire properties have hipped roofs where no single pitch is large enough to accommodate a 4kWp south facing array. Splitting the array across the south west and south east faces, or across the east and west faces, may be the practical answer.

A practical decision framework

Use this simple decision framework:

• If you have a clear south facing roof and you are installing battery storage: go south facing.
• If you have a clear south facing roof and the household is occupied during the day: go south facing.
• If you have a clear south facing roof but no battery and an empty house from 9am to 4pm: still south facing usually wins, but the difference is smaller than it looks. Consider adding a battery in the future to make the orientation pay back fully.
• If you have an east west aligned roof: go east west. The split array aligns well with normal household consumption.
• If you have a hipped roof: spread the array across multiple faces to maximise total kWp installed. Faithful Spark will calculate the optimum mix at the survey stage.
• If you only have a north facing roof: solar may not be the right investment. A north facing array generates 50% to 65% of the south facing equivalent, which often does not deliver a positive financial return at current panel prices and electricity rates.

The other factors that affect orientation choice

Roof pitch

A 30 to 40 degree pitch is optimum for solar in Scotland. Steeper pitches (45 to 60 degrees) reduce summer generation slightly but improve winter generation by catching the lower sun angle. Shallow pitches (10 to 25 degrees) reduce winter performance more significantly. The optimum pitch interacts with orientation: a south facing 35 degree pitch is the textbook ideal, but a south facing 50 degree pitch still performs strongly because the steep angle catches the winter sun.

Shading

Shading from chimneys, dormers, neighbouring properties, or trees affects different orientations differently. East facing arrays are sensitive to morning shading from trees to the east. West facing arrays are sensitive to afternoon shading. A south facing array is sensitive to shading directly to the south, often from chimneys on the same property. Faithful Spark carries out a shading assessment at the survey stage using horizon and solar path data to identify any orientation where shading materially affects output.

Roof area

The available roof area constrains how many panels you can fit. A south facing roof with 30 square metres of usable space accommodates approximately 16 panels, allowing systems up to 6kWp or so with current panel wattages. A hipped roof with limited area on each face may accommodate only 8 to 10 panels regardless of orientation choice. The system size matters more than the orientation in many cases.

Frequently asked questions

Should I install north facing solar at all?

For most Scottish properties, north facing solar does not deliver a positive financial return on its own at current panel and electricity prices. The exception is where the north facing array is added to an existing south facing array as part of a larger system, where the shared inverter, scaffold, and installation costs reduce the marginal cost per kWp on the north facing pitch. Faithful Spark advises on a case by case basis at survey.

Does the answer change if I have a battery?

Yes. With battery storage, south facing nearly always wins because the battery captures the midday peak and releases it in the evening. The total generation matters more than the timing because all generation can be captured. For households planning battery storage either now or in the future, prioritise the south facing roof if it is available.

What about south east or south west facing?

South east and south west are very nearly as good as south. Generation is approximately 90% to 95% of due south. The peak is shifted slightly earlier (south east) or later (south west) in the day, which can actually align better with household consumption. There is no need to refuse a south east or south west pitch in pursuit of due south orientation; these are excellent solar pitches.

Can I split panels across more than two faces?

Yes. Many Aberdeenshire hipped roofs accommodate panels across three faces (south, south east, south west). With micro inverters or DC optimisers, each panel operates independently, so multiple orientations within the same system perform well. A string inverter system with mixed orientations needs careful design with separate inverter inputs for each orientation. Faithful Spark designs the inverter setup to suit the specific roof at the survey stage.

Book a free survey for the right orientation

The right orientation for your property depends on the roof you have, your consumption pattern, and whether you are adding battery storage. Faithful Spark assesses all of these at the free survey and provides a written quote with the proposed orientation and estimated annual generation. See our guide on how solar performs in Scotland for the underlying climate context, and our full guide to solar panel installation in Aberdeen.

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Faithful Spark Electricians. NICEIC approved. Local Aberdeen team. Serving Aberdeen, Peterhead, Ellon, Fraserburgh and across Aberdeenshire.