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Big Roof Britain Solar Payback Index Standing Charge Drag

Solar Panels in CM18 (Harlow)

See if solar pays off for you in Harlow — 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
12.1 years
After this, it's pure profit
Upfront Cost
£8,138
What you pay to get started
Annual Benefit
£673
What you save every year
Profit Over 25 Years
£8,676
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 1012 kWh/kW — 3 above the regional median (1009).

Read the full story

A typical roof here lands around 4.0 kW, with most eligible homes comfortably fitting within 3–6 kW. Each kilowatt of panels produces roughly 1012 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)
1012 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: £841, Upfront: £10,173, 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 2024 kWh 810 kWh 1215 kWh £215 £121 £336 £4,069 12.1 yrs £2,657
3 kW 3036 kWh 1215 kWh 1822 kWh £322 £182 £504 £6,104 12.1 yrs £3,985
4 kW 4049 kWh 1619 kWh 2429 kWh £430 £243 £673 £8,138 12.1 yrs £5,313
5 kW 5061 kWh 2024 kWh 3036 kWh £537 £304 £841 £10,173 12.1 yrs £6,641
6 kW 6073 kWh 2429 kWh 3644 kWh £644 £364 £1,009 £12,207 12.1 yrs £7,970
7 kW 7085 kWh 2834 kWh 4251 kWh £752 £425 £1,177 £14,242 12.1 yrs £9,298
8 kW 8097 kWh 3239 kWh 4858 kWh £859 £486 £1,345 £16,276 12.1 yrs £10,626

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: £1,008, Upfront: £12,273, Break-even: 12.2 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2024 kWh 1215 kWh 810 kWh £322 £81 £403 £6,169 15.3 yrs £1,895
3 kW 3036 kWh 1822 kWh 1215 kWh £483 £121 £605 £8,204 13.6 yrs £3,892
4 kW 4049 kWh 2429 kWh 1619 kWh £644 £162 £806 £10,238 12.7 yrs £5,890
5 kW 5061 kWh 3036 kWh 2024 kWh £806 £202 £1,008 £12,273 12.2 yrs £7,887
6 kW 6073 kWh 3644 kWh 2429 kWh £967 £243 £1,210 £14,307 11.8 yrs £9,885
7 kW 7085 kWh 4251 kWh 2834 kWh £1,128 £283 £1,411 £16,342 11.6 yrs £11,882
8 kW 8097 kWh 4858 kWh 3239 kWh £1,289 £324 £1,613 £18,376 11.4 yrs £13,880

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: £1,092, Upfront: £13,673, Break-even: 12.5 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2024 kWh 1417 kWh 607 kWh £376 £61 £437 £7,569 17.3 yrs £1,164
3 kW 3036 kWh 2126 kWh 911 kWh £564 £91 £655 £9,604 14.7 yrs £3,496
4 kW 4049 kWh 2834 kWh 1215 kWh £752 £121 £873 £11,638 13.3 yrs £5,828
5 kW 5061 kWh 3543 kWh 1518 kWh £940 £152 £1,092 £13,673 12.5 yrs £8,161
6 kW 6073 kWh 4251 kWh 1822 kWh £1,128 £182 £1,310 £15,707 12.0 yrs £10,493
7 kW 7085 kWh 4960 kWh 2126 kWh £1,316 £213 £1,528 £17,742 11.6 yrs £12,825
8 kW 8097 kWh 5668 kWh 2429 kWh £1,504 £243 £1,747 £19,776 11.3 yrs £15,157

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: £1,117, Upfront: £15,423, Break-even: 13.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2024 kWh 1478 kWh 547 kWh £392 £55 £447 £9,319 20.9 yrs £-385
3 kW 3036 kWh 2217 kWh 820 kWh £588 £82 £670 £11,354 16.9 yrs £2,047
4 kW 4049 kWh 2955 kWh 1093 kWh £784 £109 £893 £13,388 15.0 yrs £4,480
5 kW 5061 kWh 3694 kWh 1366 kWh £980 £137 £1,117 £15,423 13.8 yrs £6,912
6 kW 6073 kWh 4433 kWh 1640 kWh £1,176 £164 £1,340 £17,457 13.0 yrs £9,345
7 kW 7085 kWh 5172 kWh 1913 kWh £1,372 £191 £1,563 £19,492 12.5 yrs £11,777
8 kW 8097 kWh 5911 kWh 2186 kWh £1,568 £219 £1,787 £21,526 12.0 yrs £14,210

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: £1,133, Upfront: £17,173, Break-even: 15.2 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2024 kWh 1518 kWh 506 kWh £403 £51 £453 £11,069 24.4 yrs £-2,001
3 kW 3036 kWh 2277 kWh 759 kWh £604 £76 £680 £13,104 19.3 yrs £498
4 kW 4049 kWh 3036 kWh 1012 kWh £806 £101 £907 £15,138 16.7 yrs £2,998
5 kW 5061 kWh 3796 kWh 1265 kWh £1,007 £127 £1,133 £17,173 15.2 yrs £5,497
6 kW 6073 kWh 4555 kWh 1518 kWh £1,208 £152 £1,360 £19,207 14.1 yrs £7,996
7 kW 7085 kWh 5314 kWh 1771 kWh £1,410 £177 £1,587 £21,242 13.4 yrs £10,496
8 kW 8097 kWh 6073 kWh 2024 kWh £1,611 £202 £1,814 £23,276 12.8 yrs £12,995

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: £1,150, Upfront: £19,623, Break-even: 17.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2024 kWh 1559 kWh 466 kWh £414 £47 £460 £13,519 29.4 yrs £-4,317
3 kW 3036 kWh 2338 kWh 698 kWh £620 £70 £690 £15,554 22.5 yrs £-1,751
4 kW 4049 kWh 3117 kWh 931 kWh £827 £93 £920 £17,588 19.1 yrs £815
5 kW 5061 kWh 3897 kWh 1164 kWh £1,034 £116 £1,150 £19,623 17.1 yrs £3,382
6 kW 6073 kWh 4676 kWh 1397 kWh £1,241 £140 £1,380 £21,657 15.7 yrs £5,948
7 kW 7085 kWh 5455 kWh 1630 kWh £1,447 £163 £1,610 £23,692 14.7 yrs £8,514
8 kW 8097 kWh 6235 kWh 1862 kWh £1,654 £186 £1,840 £25,726 14.0 yrs £11,081

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 CM18

Figures below are tailored to CM18 — click through for full league tables.

Big-Roof Britain Rank #1840 of 2182
4.4 kWp (UK avg 5.1 kWp)
~9 panels (≈430 W)
Solar Payback Index Rank #505 of 2997
10.5 years (UK avg 11.3 years)
~£773 /yr • £8,138 upfront
Standing-Charge Drag Rank #2049 of 2997
22.8% (UK avg 21.7%) drag on savings
£176 fixed • ~£773 /yr value

Your Area at a Glance

Your Electricity Rate
26.53p/kWh
Daily Fixed Charge
48.25p/day
Local Sunshine
1012kWh/kW
A 1 kW system generates ~1012 kWh per year. A typical home uses ~2,700 kWh per year.
Typical System Size
4.0kW
For houses & bungalows in this area

Local Property Data

Property Types

Houses: 66% • Flats: 27% • Bungalows: 4% Based on 6,703 properties

Coverage

Harlow (100%)

Areas Covered

Bush Fair, Latton Bush & Stewards, Passmores, Little Parndon & Town Centre, Sumners & Kingsmoor, Great Parndon, Epping West & Rural, North Weald Bassett

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

CM19 (Harlow)
≈1.9 km away
Local sunshine: ~1,006 kWh/kWp · -1% vs CM18
CM20 (Harlow)
≈1.9 km away
Local sunshine: ~1,006 kWh/kWp · -1% vs CM18
CM17 (Harlow)
≈2.9 km away
Local sunshine: ~1,012 kWh/kWp · +0% vs CM18
CM92 (Harlow)
≈3.3 km away
Local sunshine: ~1,006 kWh/kWp · -1% vs CM18
CM16 (Epping Forest)
≈6.3 km away
Local sunshine: ~1,010 kWh/kWp · -0% vs CM18
CM21 (East Hertfordshire)
≈7.0 km away
Local sunshine: ~1,011 kWh/kWp · -0% vs CM18

Similar sunshine across the UK

BR7 (Bromley)
~1,012 kWh/kWp · -0% vs CM18
TA18 (Somerset)
~1,012 kWh/kWp · +0% vs CM18
SA16 (Carmarthenshire)
~1,012 kWh/kWp · +0% vs CM18