Generation Until 9pm: West-Facing’s Summer Evening Bonus
West-facing roofs are not only viable for solar — they can actually be advantageous for many households. While you’ll generate about 15-17% less than a south-facing equivalent, your electricity production peaks in the afternoon and extends into the evening. For households that use most of their electricity after 3pm, this timing can improve self-consumption and deliver returns that rival south-facing systems. Check your west-facing roof’s exact potential with our solar roof suitability calculator.
Think about when your home is busiest: children home from school, dinner being cooked, devices charging, the TV on. This late afternoon and evening period is exactly when west-facing panels are generating their strongest output. That’s a natural alignment that south-facing systems — which peak when most families are out — can’t match. If shading is a concern, our shading impact calculator can help you understand how afternoon shadows might affect your output.
This guide covers everything you need to know about west-facing solar — realistic output expectations, how afternoon generation affects your savings, and why combining west with an east-facing slope might give you the best of all worlds.
West-Facing Solar at a Glance
| Output vs south-facing | 80-86% |
| Annual generation (4kW system) | 2,720-2,920 kWh (vs 3,400 kWh south) |
| Peak generation time | 1pm-5pm |
| Payback period | 9-13 years |
| Recommendation | Absolutely worthwhile — especially for afternoon/evening households |
How Much Will a West-Facing Roof Generate?
Output by Orientation
| Roof Orientation | Output vs South | 4kW System Annual Generation |
|---|---|---|
| South | 100% | 3,400 kWh |
| South-east | 96% | 3,264 kWh |
| South-west | 96% | 3,264 kWh |
| East | 80-86% | 2,720-2,920 kWh |
| West | 80-86% | 2,720-2,920 kWh |
| North-east | 70% | 2,380 kWh |
| North-west | 70% | 2,380 kWh |
| North | 55-60% | 1,870-2,040 kWh |
West and east-facing roofs generate the same total amount annually — the difference is purely in timing. The output range (80-86%) depends on your exact orientation (due west vs slightly south of west) and roof pitch.
Roof Pitch Impact
| Roof Pitch | West-Facing Output vs South |
|---|---|
| 15-20° (low) | 85-88% |
| 25-30° (moderate) | 83-86% |
| 35-40° (typical UK) | 80-84% |
| 45-50° (steep) | 77-81% |
Even at steep pitches, west-facing roofs perform well. The orientation reduction is modest and still delivers strong returns.
The Afternoon Generation Advantage
West-facing panels generate most of their electricity from midday onwards, peaking in the afternoon and continuing into early evening. This creates a fundamentally different generation profile from south-facing systems:
Typical Daily Generation Pattern
| Time | South-Facing Output | West-Facing Output |
|---|---|---|
| 6am-8am | Low (5-15%) | Very low (0-5%) |
| 8am-10am | Rising (30-60%) | Low (10-25%) |
| 10am-12pm | High (70-90%) | Moderate (30-55%) |
| 12pm-2pm | Peak (90-100%) | Rising (55-80%) |
| 2pm-4pm | High (70-90%) | Peak (85-100%) |
| 4pm-6pm | Declining (30-60%) | High (60-85%) |
| 6pm-8pm | Low (5-20%) | Moderate (20-45%) |
| 8pm-9pm | Very low (0-5%) | Low (5-15%) |
When Afternoon Generation Helps
West-facing solar can significantly improve self-consumption for certain households:
- Families with school-age children: Home from 3:30pm onwards — snacks, homework, screens, cooking
- Couples returning from work: Home by 5-6pm — cooking dinner, running appliances
- Evening cooking: Electric oven and hob running 4-7pm
- EV charging after work: Plug in at 5-6pm, still catching solar until 8-9pm in summer
- Air conditioning: Afternoon is often hottest — AC peaks when west panels do
- Hot tub/pool heating: Afternoon top-up before evening use
When Afternoon Generation Is Less Ideal
- WFH with early finish: If you work 7am-3pm, south/east may suit better
- Morning-heavy usage: Breakfast, morning routines, leaving by 8am
- Overnight EV charging: If you prefer cheap overnight rates anyway
The Financial Picture
Comparing South vs West: Same House, Same System
| Factor | South-Facing | West-Facing |
|---|---|---|
| System size | 4kW | 4kW |
| Installation cost | £5,800 | £5,800 |
| Annual generation | 3,400 kWh | 2,820 kWh |
| Self-consumption (45%) | 1,530 kWh | 1,269 kWh |
| Export | 1,870 kWh | 1,551 kWh |
| Savings (self-use × 28p) | £428 | £355 |
| Export income (× 10p) | £187 | £155 |
| Total annual benefit | £615 | £510 |
| Payback period | 9.4 years | 11.4 years |
With equal self-consumption rates, the west-facing system delivers about 83% of the south-facing benefit. But the story changes when usage patterns are considered.
25-Year Comparison
| Factor | South-Facing | West-Facing |
|---|---|---|
| Total generation | 81,600 kWh | 67,680 kWh |
| Total savings (with inflation) | £22,200 | £18,400 |
| Net profit after cost | £16,400 | £12,600 |
| Return on investment | 283% | 217% |
Over 25 years, a west-facing system still delivers over £12,000 net profit — a strong return on a £5,800 investment.
West-Facing With Higher Self-Consumption
The real advantage of west-facing emerges when your usage pattern aligns with afternoon generation:
Scenario: Afternoon-Active Family
The Clarkes are a family of four. Both parents work, children come home at 3:30pm, and the household is busy from 4-9pm with cooking, homework, TV, and devices. Very little electricity is used during the day.
| Factor | South-Facing (40% SC) | West-Facing (55% SC) |
|---|---|---|
| Annual generation | 3,400 kWh | 2,820 kWh |
| Self-consumption | 1,360 kWh | 1,551 kWh |
| Export | 2,040 kWh | 1,269 kWh |
| Savings (self-use × 28p) | £381 | £434 |
| Export income (× 10p) | £204 | £127 |
| Total annual benefit | £585 | £561 |
With better-aligned usage, the gap nearly disappears. The west-facing system delivers 96% of the south-facing benefit despite generating only 83% as much electricity — because more of that electricity is used directly rather than exported at lower rates.
Scenario: EV Charging After Work
The Thompsons both work in offices and arrive home around 5:30pm. Their EV is plugged in immediately and charged through the evening.
| Factor | South-Facing (35% SC) | West-Facing (50% SC) |
|---|---|---|
| Annual generation | 3,400 kWh | 2,820 kWh |
| Self-consumption | 1,190 kWh | 1,410 kWh |
| Export | 2,210 kWh | 1,410 kWh |
| Savings (self-use × 28p) | £333 | £395 |
| Export income (× 10p) | £221 | £141 |
| Total annual benefit | £554 | £536 |
With an EV charged after work (catching the tail end of west-facing generation), west comes within 97% of south-facing returns — despite lower total generation.
West + East: The Best of Both Worlds
If your house has both east and west-facing roof slopes, using both creates an excellent combined system:
East-West Split System Benefits
| Advantage | Explanation |
|---|---|
| All-day generation | East covers morning, west covers afternoon and evening |
| Flatter output curve | No massive midday peak — more even generation |
| Better self-consumption | Generation spread matches typical household usage better |
| More total capacity | Use both roof slopes instead of just one |
| Reduced peak export | Less surplus at any given moment |
| EV charging flexibility | Morning charge (WFH) or evening charge (after work) both work |
Generation Profile Comparison
| Time | South Only | East Only | West Only | East + West |
|---|---|---|---|---|
| 7-9am | Low | High | Very low | Moderate |
| 9-11am | Rising | Peak | Low | Good |
| 11am-1pm | Peak | Declining | Rising | Good |
| 1-3pm | Peak | Low | High | Good |
| 3-5pm | Declining | Low | Peak | Good |
| 5-7pm | Low | Very low | High | Moderate |
| 7-9pm | Very low | None | Moderate | Low-Moderate |
An east-west system maintains “good” output across most of the day, while south peaks extremely high at midday but drops off either side. For households with variable usage, east-west often delivers better self-consumption.
Worked Example: East-West System
The Parkers have a 3-bed semi with east and west roof slopes, each able to accommodate 8 panels.
| Configuration | 3.2kW east + 3.2kW west = 6.4kW total |
| Installation cost | £7,800 |
| Annual generation | 4,520 kWh (83% × 6.4kW × 850) |
| Self-consumption (55%) | 2,486 kWh |
| Export | 2,034 kWh |
| Annual savings | £696 (self-use) + £203 (export) = £899 |
| Payback | 8.7 years |
| 25-year profit | £24,600 |
The east-west combination delivers faster payback than either orientation alone would achieve with the same total capacity, thanks to the better self-consumption profile.
Batteries and West-Facing Solar
Do You Need a Battery?
For west-facing systems, batteries have a different value proposition compared to south-facing:
| Scenario | Battery Value for West-Facing |
|---|---|
| Evening generation, late night usage | Moderate — store 6-8pm generation for 9pm onwards |
| Home during afternoon | Lower — already using generation directly |
| Children home from school | Lower — natural alignment already |
| East-west system | Lower — less surplus at any time |
| Very late evening usage (after 9pm) | Higher — solar finished but usage continues |
The West-Facing Battery Advantage
One advantage of west-facing over south-facing when it comes to batteries: west-facing panels generate later in the day, so there’s less time between generation and evening usage. A battery storing south-facing midday surplus must hold it for 6-8 hours until evening; west-facing afternoon surplus only needs storing for 2-4 hours.
This doesn’t change battery economics dramatically, but it can mean:
- A smaller battery may be sufficient
- Less daily cycling (better for battery longevity)
- Lower standby losses
Battery Sizing for West-Facing
| Battery Size | Cost | Best For |
|---|---|---|
| 5kWh | £2,800-£3,800 | Capturing late afternoon surplus for evening |
| 8kWh | £4,000-£5,500 | Full evening coverage |
| 10kWh | £5,000-£7,000 | Evening + overnight baseload |
System Sizing for West-Facing Roofs
Recommended Sizes by House Type
| House Type | Typical Usage | Recommended System | West-Facing Generation |
|---|---|---|---|
| 2-bed | 2,500-3,500 kWh | 3-4kW | 2,115-2,820 kWh |
| 3-bed | 3,000-4,500 kWh | 4-5kW | 2,820-3,525 kWh |
| 4-bed | 4,000-6,000 kWh | 5-7kW | 3,525-4,935 kWh |
| 5-bed | 5,000-8,000 kWh | 6-9kW | 4,230-6,345 kWh |
Should You Upsize for West-Facing?
Installing additional capacity to compensate for the orientation is a valid strategy:
| South-facing baseline | 4kW generating 3,400 kWh |
| West-facing equivalent | 4.8kW generating 3,384 kWh |
| Extra panels needed | 2 additional (10 → 12 panels) |
| Extra cost | ~£700-900 |
Adding 20% more capacity recovers the total output difference. If roof space allows, this is cost-effective.
Shading Considerations
West-facing roofs have specific shading patterns to understand:
Afternoon Shading Is Critical
Since west-facing panels generate most electricity in the afternoon and evening, shading during these hours has the biggest impact:
- Trees to the west/south-west: Block afternoon and evening sun — significant impact
- Neighbouring buildings to the west: Can shade panels from mid-afternoon
- Your own house: Parts of the roof may be shaded by other sections as sun moves west
Morning Shading Matters Less
Shading from the east has minimal impact on west-facing panels, as generation is low in the morning anyway.
Summer Evening Bonus
In summer, the sun sets in the north-west, which means west-facing panels catch very late evening sun (7-9pm). Any shading from the north-west direction affects this bonus generation period.
Shading Assessment
- Visit the property in the afternoon (2-6pm) on a sunny day
- Check for shadows cast across the west-facing roof
- Pay attention to summer sun position (further north than winter)
- Use professional shading analysis tools
Summer vs Winter Performance
Summer Advantage
West-facing panels excel in summer:
- Long evenings: Sun doesn’t set until 9pm+ in June — extended generation
- Afternoon heat: Hottest part of day = when west-facing produces most (good for AC)
- BBQ and garden time: Outdoor cooking and activities powered by solar
- Later sunset: More overlap between generation and post-work activities
Winter Consideration
In winter, all orientations generate less, but west-facing has a particular pattern:
- Sun sets early: 4pm sunset means generation stops earlier
- Morning is dark: Sun rises late, so no morning generation
- Peak shifted: Maximum output around 12-2pm, not late afternoon
For heat pump owners trying to maximise winter self-consumption, this is worth considering — though all systems generate much less in winter regardless of orientation.
Costs and Payback Summary
Typical West-Facing System Costs
| System Size | Cost | Annual Generation | Annual Savings | Payback |
|---|---|---|---|---|
| 3kW | £4,500-£5,500 | 2,115 kWh | £380-£420 | 11-13 years |
| 4kW | £5,500-£6,500 | 2,820 kWh | £490-£550 | 10-12 years |
| 5kW | £6,500-£7,500 | 3,525 kWh | £600-£680 | 10-11 years |
| 6kW | £7,500-£8,500 | 4,230 kWh | £720-£820 | 9-11 years |
| 8kW | £9,500-£10,500 | 5,640 kWh | £950-£1,100 | 9-10 years |
25-Year Returns by System Size
| System Size | Total Generation | Total Savings | Net Profit |
|---|---|---|---|
| 3kW | 50,760 kWh | £13,800 | £8,500-£9,300 |
| 4kW | 67,680 kWh | £18,400 | £12,000-£13,000 |
| 5kW | 84,600 kWh | £23,000 | £15,500-£16,500 |
| 6kW | 101,520 kWh | £27,600 | £19,000-£20,000 |
| 8kW | 135,360 kWh | £36,800 | £26,000-£27,500 |
Common Questions About West-Facing Solar
Is west better or worse than east?
They generate the same total amount — the only difference is timing. West peaks in the afternoon/evening, east in the morning. Choose based on when your household uses more electricity. For typical working families, west often aligns better with after-school/after-work usage.
Is west-facing good for EV charging?
It can be excellent. If you arrive home at 5-6pm and plug in immediately, you’ll catch 2-4 hours of solar generation in summer (less in winter). This is better than south-facing for after-work EV charging, though not as good as daytime WFH charging on any orientation.
What about west-facing with air conditioning?
Excellent alignment. AC demand peaks in the afternoon when temperatures are highest — exactly when west-facing panels are producing most. This can result in very high self-consumption for air-conditioned homes.
Should I choose west if I have both west and south available?
Use south first if space is limited — it generates 17% more. But if you have abundant roof space, combining south and west can be effective. South for midday peak, west for extended afternoon generation. This creates a longer generation window with high output.
Do I need special equipment for west-facing?
No. Standard panels and inverters work identically on any orientation. The same equipment generates electricity — just with a different daily profile.
Optimising West-Facing Solar
Maximise Afternoon Self-Consumption
- Delay appliances: Run washing machine and dishwasher in the afternoon, not morning
- Cook later: If flexible, use the oven from 4-6pm rather than 6-8pm
- EV charging: Plug in as soon as you get home to catch remaining solar
- Hot water boost: Heat water in the afternoon rather than overnight
- Pool/hot tub: Heat in the afternoon before evening use
Smart Home Integration
- Smart plugs and timers: Schedule appliances for afternoon operation
- Smart EV chargers: Zappi or similar can automatically use afternoon solar
- Immersion diverter: Sends afternoon surplus to hot water tank
- Battery management: Charge battery with late afternoon surplus
Time-of-Use Tariffs
Some tariffs have higher rates in the late afternoon/early evening (4-7pm). West-facing panels generating during these peak hours can be particularly valuable — either for self-consumption or export.
Summary
| Aspect | West-Facing Details |
|---|---|
| Output vs south | 80-86% — a modest reduction |
| Peak generation | 1pm-5pm — afternoon-weighted |
| Extended generation | Until 8-9pm in summer |
| Payback period | 9-13 years — still excellent |
| 25-year profit | £8,500-£27,500 depending on size |
| Best for | Families home after school/work, EV charging after 5pm, AC use |
| Battery need | Lower than south — less gap between generation and usage |
| Best combination | East + west for all-day generation |
| Bottom line | Absolutely worthwhile — afternoon timing can be an advantage |
West-facing solar is a thoroughly viable option that delivers strong returns. The 15-17% reduction compared to south-facing is meaningful but far from a deal-breaker. More importantly, the afternoon generation profile can actually be advantageous for many households.
For families who are out during the day and home from mid-afternoon onwards, west-facing panels generate electricity when it’s actually needed. The alignment between generation and usage can result in higher self-consumption that closes the gap with south-facing systems.
If you have both east and west roof slopes available, using both creates an excellent system with all-day generation, better self-consumption, and strong returns. Don’t let anyone tell you that west-facing isn’t worth it — for many households, it’s the ideal choice.
For general solar information, see our guide to solar panel systems. For solar panel costs across all orientations, see our comprehensive cost guide.
