Solar explained to clever people by people who are not trying to be clever
Home Regions
Insights
Big Roof Britain Solar Payback Index Standing Charge Drag

Solar Panels in WD25 (Watford)

See if solar pays off for you in Watford — 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
£821
What you save every year
Profit Over 25 Years
£10,346
After paying itself off, you're this much ahead

Ready to Get Started?

Get your free quote from Blue Ape Renewables. They'll connect you with MCS-certified installers in your area and handle all the paperwork.

Get Solar Quote →
4.8★ Trustpilot • Octopus Energy trusted partner • MCS certified • No obligation
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 988 kWh/kW — 21 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 988 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)
988 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: £821, 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 1976 kWh 790 kWh 1186 kWh £210 £119 £328 £4,069 12.4 yrs £2,497
3 kW 2964 kWh 1186 kWh 1779 kWh £315 £178 £492 £6,104 12.4 yrs £3,745
4 kW 3952 kWh 1581 kWh 2371 kWh £419 £237 £657 £8,138 12.4 yrs £4,994
5 kW 4941 kWh 1976 kWh 2964 kWh £524 £296 £821 £10,173 12.4 yrs £6,242
6 kW 5929 kWh 2371 kWh 3557 kWh £629 £356 £985 £12,207 12.4 yrs £7,491
7 kW 6917 kWh 2767 kWh 4150 kWh £734 £415 £1,149 £14,242 12.4 yrs £8,739
8 kW 7905 kWh 3162 kWh 4743 kWh £839 £474 £1,313 £16,276 12.4 yrs £9,987

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: £984, 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 1976 kWh 1186 kWh 790 kWh £315 £79 £394 £6,169 15.7 yrs £1,704
3 kW 2964 kWh 1779 kWh 1186 kWh £472 £119 £590 £8,204 13.9 yrs £3,605
4 kW 3952 kWh 2371 kWh 1581 kWh £629 £158 £787 £10,238 13.0 yrs £5,507
5 kW 4941 kWh 2964 kWh 1976 kWh £786 £198 £984 £12,273 12.5 yrs £7,409
6 kW 5929 kWh 3557 kWh 2371 kWh £944 £237 £1,181 £14,307 12.1 yrs £9,311
7 kW 6917 kWh 4150 kWh 2767 kWh £1,101 £277 £1,378 £16,342 11.9 yrs £11,212
8 kW 7905 kWh 4743 kWh 3162 kWh £1,258 £316 £1,575 £18,376 11.7 yrs £13,114

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: £1,066, Upfront: £13,673, Break-even: 12.8 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1976 kWh 1383 kWh 593 kWh £367 £59 £426 £7,569 17.8 yrs £957
3 kW 2964 kWh 2075 kWh 889 kWh £551 £89 £639 £9,604 15.0 yrs £3,185
4 kW 3952 kWh 2767 kWh 1186 kWh £734 £119 £853 £11,638 13.7 yrs £5,414
5 kW 4941 kWh 3458 kWh 1482 kWh £918 £148 £1,066 £13,673 12.8 yrs £7,642
6 kW 5929 kWh 4150 kWh 1779 kWh £1,101 £178 £1,279 £15,707 12.3 yrs £9,871
7 kW 6917 kWh 4842 kWh 2075 kWh £1,285 £208 £1,492 £17,742 11.9 yrs £12,099
8 kW 7905 kWh 5533 kWh 2371 kWh £1,468 £237 £1,705 £19,776 11.6 yrs £14,327

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: £1,090, Upfront: £15,423, Break-even: 14.1 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1976 kWh 1443 kWh 534 kWh £383 £53 £436 £9,319 21.4 yrs £-597
3 kW 2964 kWh 2164 kWh 800 kWh £574 £80 £654 £11,354 17.4 yrs £1,729
4 kW 3952 kWh 2885 kWh 1067 kWh £765 £107 £872 £13,388 15.3 yrs £4,056
5 kW 4941 kWh 3607 kWh 1334 kWh £957 £133 £1,090 £15,423 14.1 yrs £6,382
6 kW 5929 kWh 4328 kWh 1601 kWh £1,148 £160 £1,308 £17,457 13.3 yrs £8,709
7 kW 6917 kWh 5049 kWh 1868 kWh £1,340 £187 £1,526 £19,492 12.8 yrs £11,035
8 kW 7905 kWh 5771 kWh 2134 kWh £1,531 £213 £1,744 £21,526 12.3 yrs £13,362

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: £1,107, Upfront: £17,173, Break-even: 15.5 yrs
System Annual output Self-use Exported Bill saving Export income Annual benefit Upfront cost Break-even 20-year net
2 kW 1976 kWh 1482 kWh 494 kWh £393 £49 £443 £11,069 25.0 yrs £-2,216
3 kW 2964 kWh 2223 kWh 741 kWh £590 £74 £664 £13,104 19.7 yrs £175
4 kW 3952 kWh 2964 kWh 988 kWh £786 £99 £885 £15,138 17.1 yrs £2,567
5 kW 4941 kWh 3705 kWh 1235 kWh £983 £124 £1,107 £17,173 15.5 yrs £4,959
6 kW 5929 kWh 4447 kWh 1482 kWh £1,180 £148 £1,328 £19,207 14.5 yrs £7,351
7 kW 6917 kWh 5188 kWh 1729 kWh £1,376 £173 £1,549 £21,242 13.7 yrs £9,742
8 kW 7905 kWh 5929 kWh 1976 kWh £1,573 £198 £1,771 £23,276 13.1 yrs £12,134

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: £1,123, 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 1976 kWh 1522 kWh 455 kWh £404 £45 £449 £13,519 30.1 yrs £-4,536
3 kW 2964 kWh 2283 kWh 682 kWh £606 £68 £674 £15,554 23.1 yrs £-2,079
4 kW 3952 kWh 3043 kWh 909 kWh £807 £91 £898 £17,588 19.6 yrs £378
5 kW 4941 kWh 3804 kWh 1136 kWh £1,009 £114 £1,123 £19,623 17.5 yrs £2,836
6 kW 5929 kWh 4565 kWh 1364 kWh £1,211 £136 £1,347 £21,657 16.1 yrs £5,293
7 kW 6917 kWh 5326 kWh 1591 kWh £1,413 £159 £1,572 £23,692 15.1 yrs £7,750
8 kW 7905 kWh 6087 kWh 1818 kWh £1,615 £182 £1,797 £25,726 14.3 yrs £10,207

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 WD25

Figures below are tailored to WD25 — click through for full league tables.

Big-Roof Britain Rank #1687 of 2182
4.5 kWp (UK avg 5.1 kWp)
~10 panels (≈430 W)
Solar Payback Index Rank #1093 of 2997
10.8 years (UK avg 11.3 years)
~£943 /yr • £10,173 upfront
Standing-Charge Drag Rank #1209 of 2997
18.7% (UK avg 21.7%) drag on savings
£176 fixed • ~£943 /yr value

Your Area at a Glance

Your Electricity Rate
26.53p/kWh
Daily Fixed Charge
48.25p/day
Local Sunshine
988kWh/kW
A 1 kW system generates ~988 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: 60% • Flats: 32% • Bungalows: 4% Based on 7,167 properties

Coverage

Watford (72%)|Hertsmere (15%)|Three Rivers (12%)|St Albans (1%)

Areas Covered

Woodside, Meriden, Stanborough, Holywell, Leavesden, Aldenham West, Bushey North, Bushey St James + 3 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

WD24 (Watford)
≈1.7 km away
Local sunshine: ~985 kWh/kWp · -0% vs WD25
WD2 (Watford)
≈1.8 km away
Local sunshine: ~992 kWh/kWp · +0% vs WD25
WD5 (Three Rivers)
≈2.5 km away
Local sunshine: ~988 kWh/kWp · +0% vs WD25
WD17 (Watford)
≈3.1 km away
Local sunshine: ~985 kWh/kWp · -0% vs WD25
WD1 (Watford)
≈4.0 km away
Local sunshine: ~991 kWh/kWp · +0% vs WD25
WD99 (Watford)
≈4.7 km away
Local sunshine: ~991 kWh/kWp · +0% vs WD25

Similar sunshine across the UK

TR9 (Cornwall)
~988 kWh/kWp · +0% vs WD25
OX8 (West Oxfordshire)
~988 kWh/kWp · +0% vs WD25
BA5 (Somerset)
~988 kWh/kWp · -0% vs WD25