Solar yield by roof orientation and angle. The 2027 numbers for every Australian capital.

Solar generation depends heavily on roof orientation and pitch. North-facing roofs deliver substantially more annual generation than south-facing roofs. East and west each deliver useful but lower output. The specific numbers are knowable - and they materially affect the financial case for solar.

This post provides the 2027 yield numbers for each major orientation across Australian capital cities, plus the implications for siting decisions on multi-roof-face dwellings.

The base case: north-facing, 30° pitch

Across Australian capital cities, a north-facing roof at the optimal pitch (approximately equal to the latitude) delivers maximum annual generation. The 30° pitch is the standard residential reference because it is the most common new-build pitch and works well for most latitudes.

Annual generation per kW of installed panels (north-facing, 30° pitch)

• Sydney: 1,420 kWh/kW (3.9 kWh/kW/day average)
• Melbourne: 1,290 kWh/kW (3.5 kWh/kW/day average)
• Brisbane: 1,520 kWh/kW (4.2 kWh/kW/day average)
• Perth: 1,640 kWh/kW (4.5 kWh/kW/day average)
• Adelaide: 1,540 kWh/kW (4.2 kWh/kW/day average)
• Hobart: 1,180 kWh/kW (3.2 kWh/kW/day average)
• Darwin: 1,720 kWh/kW (4.7 kWh/kW/day average)
• Canberra: 1,470 kWh/kW (4.0 kWh/kW/day average)

For a typical 10kW residential system:

• Sydney: 14,200 kWh/year
• Melbourne: 12,900 kWh/year
• Brisbane: 15,200 kWh/year
• Perth: 16,400 kWh/year

Orientation adjustments

For other roof orientations, the yield differs from the north-facing baseline:

East-facing (typical 30° pitch)

• Sydney: 85% of north baseline = 1,207 kWh/kW
• Melbourne: 83% = 1,071 kWh/kW
• Brisbane: 88% = 1,338 kWh/kW
• Perth: 87% = 1,427 kWh/kW

West-facing (typical 30° pitch)

• Sydney: 85% of north baseline = 1,207 kWh/kW
• Melbourne: 83% = 1,071 kWh/kW
• Brisbane: 88% = 1,338 kWh/kW
• Perth: 87% = 1,427 kWh/kW

South-facing (typical 30° pitch)

• Sydney: 65% of north baseline = 923 kWh/kW
• Melbourne: 60% = 774 kWh/kW
• Brisbane: 70% = 1,064 kWh/kW
• Perth: 68% = 1,115 kWh/kW

Flat roof (0° pitch)

• Sydney: 88% of north-30° baseline = 1,250 kWh/kW
• Melbourne: 82% = 1,058 kWh/kW
• Brisbane: 92% = 1,398 kWh/kW
• Perth: 92% = 1,509 kWh/kW

Flat roof installations typically use tilted mounting frames to optimise output, but the base flat-roof yield is provided for reference.

Pitch adjustments

For other pitches (north-facing):

15° pitch (low-pitch contemporary roof)

• Sydney: 95% of 30° baseline = 1,349 kWh/kW
• Melbourne: 93% = 1,200 kWh/kW
• Brisbane: 97% = 1,474 kWh/kW
• Perth: 96% = 1,574 kWh/kW

22.5° pitch (standard residential)

• Sydney: 99% of 30° baseline = 1,406 kWh/kW
• Melbourne: 98% = 1,264 kWh/kW
• Brisbane: 100% = 1,520 kWh/kW
• Perth: 99% = 1,624 kWh/kW

30° pitch (steep modern)

100% of baseline (reference case).

45° pitch (steep traditional)

• Sydney: 93% of 30° baseline = 1,321 kWh/kW
• Melbourne: 96% = 1,238 kWh/kW
• Brisbane: 89% = 1,353 kWh/kW
• Perth: 91% = 1,492 kWh/kW

Which orientation should you install on

For multi-roof-face dwellings, the orientation decision depends on three factors:

Factor 1: maximise total generation

If maximising total annual generation is the priority, prefer:

1. North-facing (highest yield)
2. East or west (similar to each other)
3. Avoid south unless necessary

Factor 2: match generation to consumption profile

Many households consume most electricity in the morning (breakfast, getting ready) and evening (cooking, evening activities), with lower midday consumption.

For these households:

• East-facing panels (morning generation) and west-facing panels (afternoon/evening) match consumption better than north-facing (midday peak)
• East + west split may deliver more self-consumption (lower export to grid) than pure north
• With current feed-in tariffs (typically 4-8 cents/kWh) substantially below retail rates (typically 28-38 cents/kWh), self-consumption is more valuable than export

Factor 3: roof and structural constraints

Practical roof constraints often determine orientation:

• Available roof area on each face
• Shading from adjacent buildings, trees, chimneys
• Structural condition and load capacity
• Aesthetic considerations (heritage, council requirements)
• Mounting feasibility

Real-world yield reduction factors

The theoretical yields above are derated in practice by:

Factor 1: temperature derating

Solar panel efficiency decreases as panel temperature increases. Typical loss: 5-10% on hot days.

Factor 2: soiling

Dust, leaves, bird droppings reduce panel output. Typical loss: 2-5% across the year.

Factor 3: shading

Even partial shading on a single panel can substantially reduce string output. Microinverters or DC optimisers mitigate this.

Factor 4: inverter losses

DC to AC conversion typically 95-97% efficient. Loss: 3-5%.

Factor 5: cabling losses

Long cable runs and ageing connectors. Loss: 1-3%.

Total derating

Real-world annual generation is typically 80-90% of the theoretical yield. For planning purposes, use 85% as a working assumption.

How to estimate your specific lot

For a specific lot:

Step 1: identify roof face areas

Measure or estimate the area of each roof face. For complex roofs, identify each face separately.

Step 2: identify orientation of each face

True north is the reference. Use compass bearings:

• 0° (north) = baseline yield
• 90° (east) or 270° (west) = adjusted yield
• 180° (south) = substantially reduced yield

Step 3: identify pitch of each face

Standard pitches are 15°, 22.5°, 30°, 45°.

Step 4: apply yield numbers

Use the orientation and pitch adjustments to calculate expected yield per kW for each face.

Step 5: assess panel placement

Determine how many panels fit on each face. Standard residential panel: 1.7m x 1.0m = 1.7sqm. With spacing, typical density: 1 panel per 2.5-3sqm of usable roof area.

Step 6: calculate total system

Sum the yield contributions of each face to get total annual generation estimate.

Self-consumption and battery interaction

Solar generation only delivers value if consumed on-site or exported to grid:

Without battery storage

• Generation during the day exceeds household consumption
• Surplus is exported at feed-in tariff (typically 4-8 cents/kWh)
• Self-consumed portion saves retail rate (28-38 cents/kWh)
• Typical self-consumption: 20-40% of total generation

With battery storage

• Surplus generation stored in battery during the day
• Battery discharges during evening when household consumption is high
• Self-consumption increases to 50-80%
• Battery cost: $8,000-15,000 for 10-15 kWh system

Time-of-use tariffs

Some retailers offer time-of-use tariffs:

• Peak (typically 3-9pm): higher rate
• Off-peak (overnight): lower rate
• Shoulder: mid-rate

Battery systems with time-of-use optimisation can substantially improve economics by discharging during peak rate periods.

The 2027 specific context

Three 2027-specific factors:

Factor 1: rising electricity prices

Retail electricity prices have risen substantially since 2022. Current typical residential rates: 28-42 cents/kWh depending on state and retailer. Self-consumed solar continues to deliver compelling savings.

Factor 2: declining feed-in tariffs

Feed-in tariffs have decreased as grid solar penetration has increased. Some networks now offer 0-4 cents/kWh export rates. Self-consumption is more important than ever.

Factor 3: battery cost trajectory

Battery costs have continued to decline. A 10kWh battery now typically $7,500-10,000 installed (down from $12,000-15,000 in 2022). Battery payback periods have compressed from 12-15 years to 7-10 years.

Solar yield is one of the most quantifiable aspects of residential property. The numbers are knowable, the calculations are straightforward, and the financial outcomes are predictable. Buyers considering solar installation should understand the orientation and pitch of their roof, the consumption profile of their household, and the realistic payback period for any system they consider.