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Big Roof Britain Solar Payback Index Standing Charge Drag

Solar Panels in CM4 (Brentwood)

See if solar pays off for you in Brentwood — price, savings and payback in under a minute (official UK data).

Solar Calculator

Change the settings below to see how costs and savings work for your situation.

System Size

Roof Direction

Battery Storage

Export Value

Your Numbers

Break-even
12.0 years
After this, it's pure profit
Upfront Cost
£12,207
What you pay to get started
Annual Benefit
£1,019
What you save every year
Profit Over 25 Years
£13,275
After paying itself off, you're this much ahead

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How we calculate this

Solar generation: Based on typical south-facing roof at 35° angle. We account for weather, dirt, and system losses (14%).

How much you'll use directly:

  • Without battery: You'll use about 40% of what you generate. The rest gets sold back to the grid.
  • With 5 kWh battery: You'll use about 70% (battery stores extra for evening use).
  • With 10 kWh battery: You'll use about 75% (more storage means less exported).
  • Panel-only payback: Bigger systems don’t shorten payback—cost and savings rise together per kW.
  • Battery & payback: Batteries raise self-use and cut bills, but added hardware cost often lengthens break-even at typical UK rates.
  • When a battery can still make sense:
    • Evening-heavy usage patterns
    • Time-of-use tariffs / cheap night rates
    • Low export rate vs. high unit rate
    • Heat pump or EV charging synergy
    • Optional backup/resilience (system-dependent)
    • Lower evening-hour CO₂ vs. grid

Costs: Battery prices are typically £700 per kWh. Export tariffs vary by supplier (usually 5–15p per kWh).

Grid connection: Systems up to about 3.7 kW typically need just a notification (G98). Larger systems may need permission (G99).

These are typical values based on average usage patterns. Your actual results will vary based on your roof, shading, and how you use electricity.

Your area in context

In Eastern, the current unit rate is 26.53p/kWh with a 48.25p/day standing charge. Your postcode’s south-facing sunshine yield is 1023 kWh/kW — 14 above the regional median (1009).

Read the full story

A typical roof here lands around 6.0 kW, with most eligible homes comfortably fitting within 3–6 kW. Each kilowatt of panels produces roughly 1023 kWh per year on a south-facing roof. We value self-used electricity at 26.5p and exported surplus at a baseline 10p via SEG. Use the calculator above for your exact tariff.

Unit rate
26.5p/kWh
Standing charge
48.2p/day
Sunshine yield (south)
1023 kWh/kW
Export price (baseline)
10p/kWh

Browse the scenarios below. Each battery size has its own expand — open the one that matches your plan (or just explore). For each system size (2–8 kW) we show annual output, how much you use directly, what gets exported, annual benefit, upfront cost, break-even, and a 20-year net. Negative numbers are possible — that’s the honest trade-off when adding more battery than your usage profile justifies.

No battery 5 kW example → Annual benefit: £849, Upfront: £10,173, Break-even: 12.0 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2045 kWh 818 kWh 1227 kWh £217 £123 £340 £4,069 12.0 yrs £2,726
3 kW 3068 kWh 1227 kWh 1841 kWh £326 £184 £510 £6,104 12.0 yrs £4,089
4 kW 4090 kWh 1636 kWh 2454 kWh £434 £245 £680 £8,138 12.0 yrs £5,452
5 kW 5113 kWh 2045 kWh 3068 kWh £543 £307 £849 £10,173 12.0 yrs £6,815
6 kW 6136 kWh 2454 kWh 3681 kWh £651 £368 £1,019 £12,207 12.0 yrs £8,178
7 kW 7158 kWh 2863 kWh 4295 kWh £760 £430 £1,189 £14,242 12.0 yrs £9,541
8 kW 8181 kWh 3272 kWh 4909 kWh £868 £491 £1,359 £16,276 12.0 yrs £10,904

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 2,035, battery £/kWh = 700.

3 kWh battery 5 kW example → Annual benefit: £1,018, Upfront: £12,273, Break-even: 12.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2045 kWh 1227 kWh 818 kWh £326 £82 £407 £6,169 15.1 yrs £1,978
3 kW 3068 kWh 1841 kWh 1227 kWh £488 £123 £611 £8,204 13.4 yrs £4,018
4 kW 4090 kWh 2454 kWh 1636 kWh £651 £164 £815 £10,238 12.6 yrs £6,057
5 kW 5113 kWh 3068 kWh 2045 kWh £814 £205 £1,018 £12,273 12.1 yrs £8,096
6 kW 6136 kWh 3681 kWh 2454 kWh £977 £245 £1,222 £14,307 11.7 yrs £10,135
7 kW 7158 kWh 4295 kWh 2863 kWh £1,139 £286 £1,426 £16,342 11.5 yrs £12,174
8 kW 8181 kWh 4909 kWh 3272 kWh £1,302 £327 £1,629 £18,376 11.3 yrs £14,214

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 2,035, battery £/kWh = 700.

5 kWh battery 5 kW example → Annual benefit: £1,103, Upfront: £13,673, Break-even: 12.4 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2045 kWh 1432 kWh 614 kWh £380 £61 £441 £7,569 17.2 yrs £1,255
3 kW 3068 kWh 2148 kWh 920 kWh £570 £92 £662 £9,604 14.5 yrs £3,632
4 kW 4090 kWh 2863 kWh 1227 kWh £760 £123 £882 £11,638 13.2 yrs £6,009
5 kW 5113 kWh 3579 kWh 1534 kWh £950 £153 £1,103 £13,673 12.4 yrs £8,386
6 kW 6136 kWh 4295 kWh 1841 kWh £1,139 £184 £1,324 £15,707 11.9 yrs £10,764
7 kW 7158 kWh 5011 kWh 2148 kWh £1,329 £215 £1,544 £17,742 11.5 yrs £13,141
8 kW 8181 kWh 5727 kWh 2454 kWh £1,519 £245 £1,765 £19,776 11.2 yrs £15,518

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 2,035, battery £/kWh = 700.

7.5 kWh battery 5 kW example → Annual benefit: £1,128, Upfront: £15,423, Break-even: 13.7 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2045 kWh 1493 kWh 552 kWh £396 £55 £451 £9,319 20.6 yrs £-293
3 kW 3068 kWh 2240 kWh 828 kWh £594 £83 £677 £11,354 16.8 yrs £2,186
4 kW 4090 kWh 2986 kWh 1104 kWh £792 £110 £903 £13,388 14.8 yrs £4,665
5 kW 5113 kWh 3733 kWh 1381 kWh £990 £138 £1,128 £15,423 13.7 yrs £7,144
6 kW 6136 kWh 4479 kWh 1657 kWh £1,188 £166 £1,354 £17,457 12.9 yrs £9,622
7 kW 7158 kWh 5226 kWh 1933 kWh £1,386 £193 £1,580 £19,492 12.3 yrs £12,101
8 kW 8181 kWh 5972 kWh 2209 kWh £1,584 £221 £1,805 £21,526 11.9 yrs £14,580

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 2,035, battery £/kWh = 700.

10 kWh battery 5 kW example → Annual benefit: £1,145, Upfront: £17,173, Break-even: 15.0 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2045 kWh 1534 kWh 511 kWh £407 £51 £458 £11,069 24.2 yrs £-1,907
3 kW 3068 kWh 2301 kWh 767 kWh £610 £77 £687 £13,104 19.1 yrs £639
4 kW 4090 kWh 3068 kWh 1023 kWh £814 £102 £916 £15,138 16.5 yrs £3,185
5 kW 5113 kWh 3835 kWh 1278 kWh £1,017 £128 £1,145 £17,173 15.0 yrs £5,732
6 kW 6136 kWh 4602 kWh 1534 kWh £1,221 £153 £1,374 £19,207 14.0 yrs £8,278
7 kW 7158 kWh 5369 kWh 1790 kWh £1,424 £179 £1,603 £21,242 13.2 yrs £10,824
8 kW 8181 kWh 6136 kWh 2045 kWh £1,628 £205 £1,832 £23,276 12.7 yrs £13,371

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 2,035, battery £/kWh = 700.

13.5 kWh battery 5 kW example → Annual benefit: £1,162, Upfront: £19,623, Break-even: 16.9 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2045 kWh 1575 kWh 470 kWh £418 £47 £465 £13,519 29.1 yrs £-4,222
3 kW 3068 kWh 2362 kWh 706 kWh £627 £71 £697 £15,554 22.3 yrs £-1,608
4 kW 4090 kWh 3150 kWh 941 kWh £836 £94 £930 £17,588 18.9 yrs £1,006
5 kW 5113 kWh 3937 kWh 1176 kWh £1,045 £118 £1,162 £19,623 16.9 yrs £3,620
6 kW 6136 kWh 4725 kWh 1411 kWh £1,253 £141 £1,395 £21,657 15.5 yrs £6,234
7 kW 7158 kWh 5512 kWh 1646 kWh £1,462 £165 £1,627 £23,692 14.6 yrs £8,848
8 kW 8181 kWh 6299 kWh 1882 kWh £1,671 £188 £1,859 £25,726 13.8 yrs £11,461

Assumptions: south-facing, sensible tilt; self-use shares from site rules; export at 10p baseline. Costs: panels £/kW = 2,035, battery £/kWh = 700.

Figures are illustrative and use the same method as the calculator above. For exact results, adjust your roof direction, tariff, and usage in the calculator.

Insights for CM4

Figures below are tailored to CM4 — click through for full league tables.

Big-Roof Britain Rank #185 of 2182
6.2 kWp (UK avg 5.1 kWp)
~13 panels (≈430 W)
Solar Payback Index Rank #392 of 2997
10.4 years (UK avg 11.3 years)
~£1,171 /yr • £12,207 upfront
Standing-Charge Drag Rank #250 of 2997
15.0% (UK avg 21.7%) drag on savings
£176 fixed • ~£1,171 /yr value

Your Area at a Glance

Your Electricity Rate
26.53p/kWh
Daily Fixed Charge
48.25p/day
Local Sunshine
1023kWh/kW
A 1 kW system generates ~1023 kWh per year. A typical home uses ~2,700 kWh per year.
Typical System Size
6.0kW
For houses & bungalows in this area

Local Property Data

Property Types

Houses: 66% • Flats: 16% • Bungalows: 17% Based on 2,864 properties

Coverage

Brentwood (64%)|Chelmsford (31%)|Epping Forest (4%)|Basildon (1%)

Areas Covered

Ingatestone, Fryerning & Mountnessing, South Hanningfield, Stock and Margaretting, Blackmore & Doddinghurst, Rural East, Chelmsford Rural West, Bicknacre and East and West Hanningfield + 4 more

Data Sources & Assumptions

Solar yield: PVGIS (EU Joint Research Centre), January 2025 data

Electricity rates: Ofgem price cap, Q4 2025

Installation costs: MCS certified installer data, March 2025

Property data: EPC open data (Open Government Licence), aggregated

All estimates are typical values. Actual results vary based on your specific situation, roof characteristics, and usage patterns.

Compare nearby areas

Nearby in Eastern

CM12 (Basildon)
≈5.5 km away
Local sunshine: ~1,033 kWh/kWp · +1% vs CM4
CM11 (Basildon)
≈6.2 km away
Local sunshine: ~1,033 kWh/kWp · +1% vs CM4
CM13 (Brentwood)
≈6.2 km away
Local sunshine: ~1,025 kWh/kWp · +0% vs CM4
CM15 (Brentwood)
≈6.7 km away
Local sunshine: ~1,012 kWh/kWp · -1% vs CM4
CM14 (Brentwood)
≈7.8 km away
Local sunshine: ~1,024 kWh/kWp · +0% vs CM4
CM2 (Chelmsford)
≈9.2 km away
Local sunshine: ~1,033 kWh/kWp · +1% vs CM4

Similar sunshine across the UK

TR8 (Cornwall)
~1,023 kWh/kWp · +0% vs CM4
SO5 (Eastleigh)
~1,022 kWh/kWp · -0% vs CM4
ME6 (Tonbridge and Malling)
~1,023 kWh/kWp · +0% vs CM4