Annual Savings by System Size
Here's what you'll actually save with different solar panel system sizes in 2026, using current Ofgem price cap electricity rates (27.69p/kWh for Q1 2026) and Smart Export Guarantee payments (12p/kWh average):
| System Size | Annual Generation | Bill Savings | Export Income | Total Annual Saving | Monthly Average |
|---|---|---|---|---|---|
| 3kW (small) | 2,700 kWh | £224 | £227 | £451 | £60 |
| 4kW (standard) | 3,600 kWh | £299 | £302 | £601 | £75 |
| 5kW (medium-large) | 4,500 kWh | £374 | £378 | £752 | £85 |
| 6kW (large) | 5,400 kWh | £448 | £454 | £902 | £95 |
| 8kW (very large) | 7,200 kWh | £598 | £605 | £1,203 | £125 |
Based on South England sunshine hours (900 kWh/kWp), 30% self-consumption, 12p export rate. Your actual savings will vary based on location, roof orientation, and usage patterns.
Monthly Savings: Summer vs Winter
Solar savings vary dramatically by season. Here's the monthly breakdown for a typical 4kW system in the Midlands:
| Month | Generation (kWh) | Bill Savings | Export Income | Total Monthly Saving |
|---|---|---|---|---|
| January | 144 | £12 | £12 | £24 |
| February | 180 | £15 | £15 | £30 |
| March | 288 | £24 | £24 | £48 |
| April | 360 | £30 | £30 | £60 |
| May | 432 | £36 | £36 | £72 |
| June | 468 | £39 | £39 | £78 |
| July | 468 | £39 | £39 | £78 |
| August | 432 | £36 | £36 | £72 |
| September | 360 | £30 | £30 | £60 |
| October | 252 | £21 | £21 | £42 |
| November | 144 | £12 | £12 | £24 |
| December | 72 | £6 | £6 | £12 |
Summer months (May-August) deliver 60% of your annual savings despite being only 33% of the year. December-January contribute just 7% of annual savings but still offset your winter bills.
Regional Savings Differences
Where you live significantly affects your solar savings due to varying sunshine hours across the UK:
| Region | 4kW System Savings/Year | Monthly Average | 25-Year Total Savings |
|---|---|---|---|
| South England | £945 | £79 | £26,500 |
| South West | £920 | £77 | £25,800 |
| Midlands | £830 | £69 | £23,200 |
| Wales | £805 | £67 | £22,500 |
| North England | £770 | £64 | £21,500 |
| Scotland | £695 | £58 | £19,400 |
| Northern Ireland | £680 | £57 | £19,000 |
Even in Scotland and Northern Ireland with lower sunshine, savings remain excellent - delivering 350%+ ROI over system lifespans.
📍 Get Your Exact Postcode-Specific Savings
Our Pro calculator uses your precise location's sunshine data for accurate monthly and annual savings projections.
Get Accurate Savings (£4.99) →How Savings Increase Over Time
Your solar savings grow year-on-year due to electricity price inflation. Here's a 10-year projection for a 4kW system with 3.5% annual price increases:
| Year | Electricity Rate | Annual Savings | Cumulative Savings |
|---|---|---|---|
| 2026 (Year 1) | 27.69p | £945 | £945 |
| Year 2 | 28.66p | £978 | £1,923 |
| Year 3 | 29.66p | £1,012 | £2,935 |
| Year 5 | 31.79p | £1,085 | £5,108 |
| Year 10 | 39.31p | £1,341 | £11,320 |
By year 10, you're saving 42% more annually than year 1. This compounding effect means your later savings far exceed initial projections.
Savings Breakdown: Where the Money Comes From
Solar panels generate savings through two mechanisms, with typical percentages for a 4kW system:
1. Bill Reduction (50% of Savings)
Every unit you generate and use during the day saves 27.69p compared to buying from the grid. With typical 30% self-consumption:
- Annual self-consumption: 1,080 kWh (30% of 3,600 kWh)
- Savings at 27.69p/kWh: £299 per year
- Increases with electricity price rises
2. Export Income (50% of Savings)
Surplus electricity exported to the grid via Smart Export Guarantee:
- Annual export: 2,520 kWh (70% of 3,600 kWh)
- Income at 12p/kWh: £302 per year
- Best rates: Octopus (15p), E.ON (12p)
Factors That Increase Your Savings
Several strategies can boost your savings 20-40% above baseline:
1. Higher Self-Consumption (30% → 50%)
Shift usage to daylight hours (washing machine, dishwasher, EV charging). This increases bill savings from £299 to £498/year (+£199).
2. Better Export Tariff (12p → 15p)
Switching from standard SEG (12p) to Octopus Outgoing Fixed (15p) adds £76/year.
3. Battery Storage
Adding a 10kWh battery (£5,000) increases self-consumption to 60%+ and enables time-shifting, adding £400-600 annual savings.
4. Optimal Panel Positioning
South-facing roof at 30-40° pitch delivers 100% of rated output. East/west facing loses 15-20%, north-facing loses 40-50%.
Real-World Example: 4-Bedroom Home in Birmingham
Setup: 5kW system (£6,500), south-west facing roof
Annual consumption: 3,800 kWh
Usage pattern: Both adults work from home 3 days/week
Year 1 Savings:
- Generation: 4,250 kWh
- Self-consumption: 45% (1,913 kWh) = £530 bill reduction
- Export: 55% (2,338 kWh) at 15p = £351 export income
- Total annual savings: £881
10-Year Projection:
- Cumulative savings: £9,850
- System cost after 0% VAT: £6,500
- Payback period: 7.4 years
- Year 10 annual saving: £1,145 (30% higher than year 1)
Will Solar Panels Completely Eliminate My Bill?
Solar panels significantly reduce but rarely eliminate electricity bills entirely. Here's why:
Typical Bill Reduction: 40-60% of annual costs
- Summer months: Bills often reduce to £0-20/month
- Winter months: Bills remain at 60-80% of pre-solar levels
- Annual average: 50% reduction from £1,800 to £900/year
To approach zero bills, you need:
- Oversized solar system (8-10kW for typical 4-bed home)
- Large battery storage (13-16kWh)
- Smart tariff for overnight charging
- High self-consumption (60%+)
- Total investment: £13,000-16,000
For most households, a standard 4-6kW system offers the best balance of cost and savings.
Calculate Your Exact Savings
Get personalised monthly and annual savings for your home. See how much you'll save in summer vs winter, and your total 25-year profit.
Use Free Calculator →Or get postcode-specific sunshine data with Pro Calculator (£4.99)