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Solar Panels in CM99 (Chelmsford)

See if solar pays off for you in Chelmsford — 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
11.8 years
After this, it's pure profit
Upfront Cost
£10,173
What you pay to get started
Annual Benefit
£863
What you save every year
Profit Over 25 Years
£11,410
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 1039 kWh/kW — 30 above the regional median (1009).

Read the full story

A typical roof here lands around 5.0 kW, with most eligible homes comfortably fitting within 3–6 kW. Each kilowatt of panels produces roughly 1039 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)
1039 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: £863, Upfront: £10,173, Break-even: 11.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2079 kWh 831 kWh 1247 kWh £221 £125 £345 £4,069 11.8 yrs £2,837
3 kW 3118 kWh 1247 kWh 1871 kWh £331 £187 £518 £6,104 11.8 yrs £4,256
4 kW 4157 kWh 1663 kWh 2494 kWh £441 £249 £691 £8,138 11.8 yrs £5,675
5 kW 5197 kWh 2079 kWh 3118 kWh £551 £312 £863 £10,173 11.8 yrs £7,093
6 kW 6236 kWh 2494 kWh 3742 kWh £662 £374 £1,036 £12,207 11.8 yrs £8,512
7 kW 7276 kWh 2910 kWh 4365 kWh £772 £437 £1,209 £14,242 11.8 yrs £9,931
8 kW 8315 kWh 3326 kWh 4989 kWh £882 £499 £1,381 £16,276 11.8 yrs £11,350

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: £1,035, Upfront: £12,273, Break-even: 11.9 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2079 kWh 1247 kWh 831 kWh £331 £83 £414 £6,169 14.9 yrs £2,112
3 kW 3118 kWh 1871 kWh 1247 kWh £496 £125 £621 £8,204 13.2 yrs £4,218
4 kW 4157 kWh 2494 kWh 1663 kWh £662 £166 £828 £10,238 12.4 yrs £6,324
5 kW 5197 kWh 3118 kWh 2079 kWh £827 £208 £1,035 £12,273 11.9 yrs £8,430
6 kW 6236 kWh 3742 kWh 2494 kWh £993 £249 £1,242 £14,307 11.5 yrs £10,536
7 kW 7276 kWh 4365 kWh 2910 kWh £1,158 £291 £1,449 £16,342 11.3 yrs £12,641
8 kW 8315 kWh 4989 kWh 3326 kWh £1,324 £333 £1,656 £18,376 11.1 yrs £14,747

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: £1,121, Upfront: £13,673, 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 2079 kWh 1455 kWh 624 kWh £386 £62 £448 £7,569 16.9 yrs £1,399
3 kW 3118 kWh 2183 kWh 935 kWh £579 £94 £673 £9,604 14.3 yrs £3,849
4 kW 4157 kWh 2910 kWh 1247 kWh £772 £125 £897 £11,638 13.0 yrs £6,298
5 kW 5197 kWh 3638 kWh 1559 kWh £965 £156 £1,121 £13,673 12.2 yrs £8,748
6 kW 6236 kWh 4365 kWh 1871 kWh £1,158 £187 £1,345 £15,707 11.7 yrs £11,197
7 kW 7276 kWh 5093 kWh 2183 kWh £1,351 £218 £1,569 £17,742 11.3 yrs £13,647
8 kW 8315 kWh 5820 kWh 2494 kWh £1,544 £249 £1,794 £19,776 11.0 yrs £16,096

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: £1,147, Upfront: £15,423, Break-even: 13.4 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2079 kWh 1517 kWh 561 kWh £403 £56 £459 £9,319 20.3 yrs £-145
3 kW 3118 kWh 2276 kWh 842 kWh £604 £84 £688 £11,354 16.5 yrs £2,408
4 kW 4157 kWh 3035 kWh 1123 kWh £805 £112 £917 £13,388 14.6 yrs £4,960
5 kW 5197 kWh 3794 kWh 1403 kWh £1,006 £140 £1,147 £15,423 13.4 yrs £7,513
6 kW 6236 kWh 4552 kWh 1684 kWh £1,208 £168 £1,376 £17,457 12.7 yrs £10,066
7 kW 7276 kWh 5311 kWh 1964 kWh £1,409 £196 £1,605 £19,492 12.1 yrs £12,618
8 kW 8315 kWh 6070 kWh 2245 kWh £1,610 £225 £1,835 £21,526 11.7 yrs £15,171

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: £1,164, Upfront: £17,173, Break-even: 14.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2079 kWh 1559 kWh 520 kWh £414 £52 £466 £11,069 23.8 yrs £-1,757
3 kW 3118 kWh 2339 kWh 780 kWh £620 £78 £698 £13,104 18.8 yrs £864
4 kW 4157 kWh 3118 kWh 1039 kWh £827 £104 £931 £15,138 16.3 yrs £3,485
5 kW 5197 kWh 3898 kWh 1299 kWh £1,034 £130 £1,164 £17,173 14.8 yrs £6,107
6 kW 6236 kWh 4677 kWh 1559 kWh £1,241 £156 £1,397 £19,207 13.8 yrs £8,728
7 kW 7276 kWh 5457 kWh 1819 kWh £1,448 £182 £1,630 £21,242 13.0 yrs £11,349
8 kW 8315 kWh 6236 kWh 2079 kWh £1,654 £208 £1,862 £23,276 12.5 yrs £13,971

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: £1,181, Upfront: £19,623, Break-even: 16.6 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 2079 kWh 1601 kWh 478 kWh £425 £48 £472 £13,519 28.6 yrs £-4,070
3 kW 3118 kWh 2401 kWh 717 kWh £637 £72 £709 £15,554 21.9 yrs £-1,380
4 kW 4157 kWh 3201 kWh 956 kWh £849 £96 £945 £17,588 18.6 yrs £1,310
5 kW 5197 kWh 4002 kWh 1195 kWh £1,062 £120 £1,181 £19,623 16.6 yrs £4,000
6 kW 6236 kWh 4802 kWh 1434 kWh £1,274 £143 £1,417 £21,657 15.3 yrs £6,690
7 kW 7276 kWh 5602 kWh 1673 kWh £1,486 £167 £1,654 £23,692 14.3 yrs £9,380
8 kW 8315 kWh 6403 kWh 1912 kWh £1,699 £191 £1,890 £25,726 13.6 yrs £12,071

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 CM99

Figures below are tailored to CM99 — click through for full league tables.

Solar Payback Index Rank #313 of 2997
10.3 years (UK avg 11.3 years)
~£992 /yr • £10,173 upfront
Standing-Charge Drag Rank #920 of 2997
17.8% (UK avg 21.7%) drag on savings
£176 fixed • ~£992 /yr value

Your Area at a Glance

Your Electricity Rate
26.53p/kWh
Daily Fixed Charge
48.25p/day
Local Sunshine
1039kWh/kW
A 1 kW system generates ~1039 kWh per year. A typical home uses ~2,700 kWh per year.
Typical System Size
5.0kW
For houses & bungalows in this area

Local Property Data

Property Types

No EPC data available for this outcode

Coverage

Chelmsford (100%)

Areas Covered

Chelmer Village and Beaulieu Park, Moulsham and Central, Great Baddow East

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

CM98 (Chelmsford)
≈1.7 km away
Local sunshine: ~1,036 kWh/kWp · -0% vs CM99
CM1 (Chelmsford)
≈1.9 km away
Local sunshine: ~1,033 kWh/kWp · -1% vs CM99
CM2 (Chelmsford)
≈2.4 km away
Local sunshine: ~1,033 kWh/kWp · -1% vs CM99
CM3 (Chelmsford)
≈6.9 km away
Local sunshine: ~1,035 kWh/kWp · -0% vs CM99
CM4 (Brentwood)
≈11.5 km away
Local sunshine: ~1,023 kWh/kWp · -2% vs CM99
CM8 (Braintree)
≈11.5 km away
Local sunshine: ~1,050 kWh/kWp · +1% vs CM99

Similar sunshine across the UK

SA71 (Pembrokeshire)
~1,039 kWh/kWp · -0% vs CM99
SA72 (Pembrokeshire)
~1,040 kWh/kWp · +0% vs CM99
ME4 (Medway)
~1,040 kWh/kWp · +0% vs CM99