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Big Roof Britain Solar Payback Index Standing Charge Drag

Solar Panels in WD6 (Hertsmere)

See if solar pays off for you in Hertsmere — 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
12.4 years
After this, it's pure profit
Upfront Cost
£10,173
What you pay to get started
Annual Benefit
£819
What you save every year
Profit Over 25 Years
£10,300
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 986 kWh/kW — 23 below 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 986 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)
986 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: £819, Upfront: £10,173, 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 1972 kWh 789 kWh 1183 kWh £209 £118 £328 £4,069 12.4 yrs £2,482
3 kW 2958 kWh 1183 kWh 1775 kWh £314 £177 £491 £6,104 12.4 yrs £3,723
4 kW 3944 kWh 1577 kWh 2366 kWh £419 £237 £655 £8,138 12.4 yrs £4,964
5 kW 4930 kWh 1972 kWh 2958 kWh £523 £296 £819 £10,173 12.4 yrs £6,206
6 kW 5916 kWh 2366 kWh 3549 kWh £628 £355 £983 £12,207 12.4 yrs £7,447
7 kW 6901 kWh 2761 kWh 4141 kWh £732 £414 £1,146 £14,242 12.4 yrs £8,688
8 kW 7887 kWh 3155 kWh 4732 kWh £837 £473 £1,310 £16,276 12.4 yrs £9,929

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: £982, Upfront: £12,273, 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 1972 kWh 1183 kWh 789 kWh £314 £79 £393 £6,169 15.7 yrs £1,686
3 kW 2958 kWh 1775 kWh 1183 kWh £471 £118 £589 £8,204 13.9 yrs £3,579
4 kW 3944 kWh 2366 kWh 1577 kWh £628 £158 £786 £10,238 13.0 yrs £5,472
5 kW 4930 kWh 2958 kWh 1972 kWh £785 £197 £982 £12,273 12.5 yrs £7,365
6 kW 5916 kWh 3549 kWh 2366 kWh £942 £237 £1,178 £14,307 12.1 yrs £9,258
7 kW 6901 kWh 4141 kWh 2761 kWh £1,099 £276 £1,375 £16,342 11.9 yrs £11,151
8 kW 7887 kWh 4732 kWh 3155 kWh £1,256 £315 £1,571 £18,376 11.7 yrs £13,044

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: £1,063, Upfront: £13,673, Break-even: 12.9 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1972 kWh 1380 kWh 592 kWh £366 £59 £425 £7,569 17.8 yrs £938
3 kW 2958 kWh 2070 kWh 887 kWh £549 £89 £638 £9,604 15.1 yrs £3,157
4 kW 3944 kWh 2761 kWh 1183 kWh £732 £118 £851 £11,638 13.7 yrs £5,376
5 kW 4930 kWh 3451 kWh 1479 kWh £915 £148 £1,063 £13,673 12.9 yrs £7,595
6 kW 5916 kWh 4141 kWh 1775 kWh £1,099 £177 £1,276 £15,707 12.3 yrs £9,814
7 kW 6901 kWh 4831 kWh 2070 kWh £1,282 £207 £1,489 £17,742 11.9 yrs £12,033
8 kW 7887 kWh 5521 kWh 2366 kWh £1,465 £237 £1,701 £19,776 11.6 yrs £14,252

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: £1,088, Upfront: £15,423, Break-even: 14.2 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1972 kWh 1439 kWh 532 kWh £382 £53 £435 £9,319 21.4 yrs £-617
3 kW 2958 kWh 2159 kWh 799 kWh £573 £80 £653 £11,354 17.4 yrs £1,700
4 kW 3944 kWh 2879 kWh 1065 kWh £764 £106 £870 £13,388 15.4 yrs £4,017
5 kW 4930 kWh 3599 kWh 1331 kWh £955 £133 £1,088 £15,423 14.2 yrs £6,334
6 kW 5916 kWh 4318 kWh 1597 kWh £1,146 £160 £1,305 £17,457 13.4 yrs £8,650
7 kW 6901 kWh 5038 kWh 1863 kWh £1,337 £186 £1,523 £19,492 12.8 yrs £10,967
8 kW 7887 kWh 5758 kWh 2130 kWh £1,528 £213 £1,740 £21,526 12.4 yrs £13,284

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: £1,104, Upfront: £17,173, Break-even: 15.6 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1972 kWh 1479 kWh 493 kWh £392 £49 £442 £11,069 25.1 yrs £-2,236
3 kW 2958 kWh 2218 kWh 739 kWh £589 £74 £662 £13,104 19.8 yrs £146
4 kW 3944 kWh 2958 kWh 986 kWh £785 £99 £883 £15,138 17.1 yrs £2,528
5 kW 4930 kWh 3697 kWh 1232 kWh £981 £123 £1,104 £17,173 15.6 yrs £4,910
6 kW 5916 kWh 4437 kWh 1479 kWh £1,177 £148 £1,325 £19,207 14.5 yrs £7,292
7 kW 6901 kWh 5176 kWh 1725 kWh £1,373 £173 £1,546 £21,242 13.7 yrs £9,673
8 kW 7887 kWh 5916 kWh 1972 kWh £1,569 £197 £1,767 £23,276 13.2 yrs £12,055

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: £1,120, Upfront: £19,623, Break-even: 17.5 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1972 kWh 1518 kWh 454 kWh £403 £45 £448 £13,519 30.2 yrs £-4,556
3 kW 2958 kWh 2277 kWh 680 kWh £604 £68 £672 £15,554 23.1 yrs £-2,109
4 kW 3944 kWh 3037 kWh 907 kWh £806 £91 £896 £17,588 19.6 yrs £338
5 kW 4930 kWh 3796 kWh 1134 kWh £1,007 £113 £1,120 £19,623 17.5 yrs £2,786
6 kW 5916 kWh 4555 kWh 1361 kWh £1,208 £136 £1,344 £21,657 16.1 yrs £5,233
7 kW 6901 kWh 5314 kWh 1587 kWh £1,410 £159 £1,569 £23,692 15.1 yrs £7,680
8 kW 7887 kWh 6073 kWh 1814 kWh £1,611 £181 £1,793 £25,726 14.4 yrs £10,127

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 WD6

Figures below are tailored to WD6 — click through for full league tables.

Big-Roof Britain Rank #1982 of 2182
4.2 kWp (UK avg 5.1 kWp)
~9 panels (≈430 W)
Solar Payback Index Rank #1096 of 2997
10.8 years (UK avg 11.3 years)
~£941 /yr • £10,173 upfront
Standing-Charge Drag Rank #1194 of 2997
18.7% (UK avg 21.7%) drag on savings
£176 fixed • ~£941 /yr value

Your Area at a Glance

Your Electricity Rate
26.53p/kWh
Daily Fixed Charge
48.25p/day
Local Sunshine
986kWh/kW
A 1 kW system generates ~986 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

Houses: 49% • Flats: 43% • Bungalows: 3% Based on 10,056 properties

Coverage

Hertsmere (100%)

Areas Covered

Borehamwood Brookmeadow, Borehamwood Cowley Hill, Borehamwood Kenilworth, Borehamwood Hillside, Elstree, Aldenham West, Shenley, Aldenham East + 1 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

WD7 (Hertsmere)
≈4.1 km away
Local sunshine: ~987 kWh/kWp · +0% vs WD6
HA8 (Barnet)
≈4.7 km away
Local sunshine: ~984 kWh/kWp · -0% vs WD6
NW7 (Barnet)
≈5.1 km away
Local sunshine: ~985 kWh/kWp · -0% vs WD6
WD23 (Hertsmere)
≈5.6 km away
Local sunshine: ~992 kWh/kWp · +1% vs WD6
HA7 (Harrow)
≈5.8 km away
Local sunshine: ~990 kWh/kWp · +0% vs WD6
EN5 (Barnet)
≈6.6 km away
Local sunshine: ~988 kWh/kWp · +0% vs WD6

Similar sunshine across the UK

SN13 (Wiltshire)
~986 kWh/kWp · +0% vs WD6
HP14 (Buckinghamshire)
~986 kWh/kWp · +0% vs WD6
BS30 (South Gloucestershire)
~986 kWh/kWp · -0% vs WD6