Middlesex
Solar panels in Harrow, priced before anyone visits.
A 12-panel roof in Harrow makes about 6,530 kWh a year and costs £6,360 installed; a free 30-minute video call sizes it to yours.
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How much a Harrow roof makes, month by month
PVGIS puts Harrow at 1,026 kWh per kWp a year, level with our Middlesex county estimate. 67% of it arrives between April and September, peaking in July.
Generation per kWp, month by month
Show the monthly figures
| Month | kWh/kWp |
|---|---|
| January | 40.5 |
| February | 54.1 |
| March | 89.1 |
| April | 115 |
| May | 122 |
| June | 123 |
| July | 125 |
| August | 111 |
| September | 95.9 |
| October | 67.3 |
| November | 47.2 |
| December | 37.4 |
Source: PVGIS v5.2 (European Commission JRC), SARAH3 database, 1 kWp, 14% system loss, 35 degree pitch, due south, checked September 2026.
Our GB average is 925 kWh per kWp a year, the mean of the 85 county PVGIS estimates we publish; at 1,026, Harrow is 11% above it.
How Harrow compares
Harrow is one of 23 Middlesex towns we track, and it ranks joint 5th of 23 for solar yield. The House of Commons Library settlement classification puts it in the core city class, with a population of 269,993, which makes it one of the largest places we publish figures for. Scale changes nothing about the physics: PVGIS gives a roof here 1,026 kWh per kWp a year, 2.81 peak sun hours a day averaged across the seasons, and on the 12p scenario about £247 of the year one benefit comes from solar you use yourself, with export income adding £671.
Every figure here assumes a clear, south-facing roof at 35 degrees. Yours will differ, which is what the free design call is for; until then, the calculator below tests panels, batteries and export rates on Harrow's own yield.
Harrow is its own local planning authority area, and its House of Commons Library settlement class is core city.
The charger is in the installed price but left out of payback: charging savings depend on your mileage and tariff, which the design call models properly.
Your real roof and usage, worked through on a free 30-minute video call. Use the full form or leave three details below.
Price this for your roof
Three details. We call or text within one working day to book your free 30-minute design call, on video or by phone if you prefer.
Generation is modelled from PVGIS satellite data for Harrow's own coordinates (51.59348, -0.33981), using the same 26.32p/kWh import value and £1,000 per kWp installed pricing as every Clearline estimate; the methodology is on our help page.
UK Power Networks and your Harrow connection
The distribution network operator (DNO) for Harrow is UK Power Networks, which runs the East England licence area.
G98 is the simple route. If the inverter, plus any battery, stays at or under 3.68kW per phase, UK Power Networks only has to be told within 28 days after the system is commissioned.
Larger systems go through G99 instead, applied for before installation. On timing: Ofgem's guaranteed standard for a low voltage generation connection quotation is 45 working days, with £80 paid for each working day late, and it binds UK Power Networks as it does every network operator.
Sources: NESO DNO licence areas (3 May 2024); Ofgem, Distributed Generation Standards Direction guidance, checked 27 September 2026. G98 vs G99, explained.
Beyond the panels: heating and car charging in Harrow
A heat pump in Harrow
In December, the darkest month here, 12 panels in Harrow make about 240 kWh. That is when a heat pump runs hardest, so its running cost in Harrow comes down to the tariff and the flow temperature rather than the roof.
In England, the Boiler Upgrade Scheme pays £7,500 towards an air source or ground source heat pump and £2,500 towards an air-to-air one, with £1,500 more until March 2027 for homes heated by oil or LPG with no mains gas (gov.uk, checked 28 September 2026).
Charging an EV in Harrow
Summer is where a car earns its place. In July, 12 panels in Harrow make about 790 kWh, against roughly 70 kWh a typical home uses in daylight that month on our calculator's typical-use settings, so there is surplus a smart charger can put into the car instead of exporting it.
Renters and flat owners with private off-street parking can get 75% off a chargepoint and its installation, up to £500 per socket, until 31 March 2027 (gov.uk, checked 28 September 2026). The calculator above adds a 7.4kW smart charger from £1,100 installed.
The packages, priced before anyone visits
Every system is designed around your roof on the free call before anything is fitted.
Solar panel servicing and repair in Harrow
If a system in Harrow is underperforming, start with the guides below: repair benchmarks, service scope, and the inverter question.
Solar in Harrow: your questions answered
How much energy would 12 solar panels make in Harrow?
Harrow averages 2.81 peak sun hours a day, which PVGIS turns into 1,026 kWh per kWp a year. On a 12-panel, 6.36 kWp roof that is about 6,530 kWh, 67% of it between April and September.
What does a typical solar system cost in Harrow?
Solar is priced at £1,000 per kWp installed wherever you live, so a 12-panel, 6.36 kWp system costs £6,360 in Harrow, exactly as it would anywhere else, before any battery. Location changes what the system makes, not what it costs: here that is about 6,530 kWh a year. The final figure comes from your roof on the design call.
Who is the network operator in Harrow, and do I need a G99 application?
The operator is UK Power Networks. Most home systems use the G98 route, a notification within 28 days of switch-on for up to 3.68kW per phase, so nothing waits on the network. Above that, G99 applies and has to be granted first. Ofgem's guaranteed standard for a low voltage generation connection quotation is 45 working days, with £80 paid for each working day late, and it binds UK Power Networks as it does every network operator. Your design call checks which route yours needs.
What happens to the solar I do not use in Harrow?
Around £671 a year at 12p per kWh, for the roughly 5,589 kWh a 12-panel system in Harrow exports with typical use. Rates vary by supplier and some need their own tariff; the export rates table is dated and sourced.
How does solar perform in Harrow in the winter months?
December is the weakest month in Harrow: about 240 kWh from 12 panels, against 790 kWh in July. The panels still generate on bright winter days; they just cover a smaller share of what the house uses.
How Harrow compares with its neighbours
How the towns nearest Harrow compare on the same PVGIS settings, closest first.
| Town | kWh per kWp a year | vs Harrow |
|---|---|---|
| Harrow | 1,026 | this town |
| Bushey | 1,024 | −2 kWh |
| Brent | 1,024 | −2 kWh |
| Ealing | 1,028 | +2 kWh |
| Borehamwood | 1,015 | −11 kWh |
| Watford | 1,013 | −13 kWh |
| Barnet | 1,016 | −10 kWh |
Each row is a PVGIS v5.2 run at that town's centre with the same settings. Treat gaps of a few kWh as noise and gaps over about 30 kWh per kWp as real differences in sunshine.
Also for Harrow: Solar panels in Harrow from OVO Solar & Battery
Also near Harrow
See a number before you speak to anyone
Answer a few questions about your roof and usage and see an instant solar and battery estimate. No email needed to see the result.
Reading for Harrow homeowners
Sourced, dated and written by us. The same ground we cover on your free call.
Why your inverter is smaller than your panel array, and why that is correct
More panel capacity than inverter capacity is a deliberate design choice.
Read the guide →What a battery gateway actually does
Without a gateway your system shuts down when the grid does. Here is what the box actually does.
Read the guide →Smart charge point regulations, explained
Why your charger arrives pre-set to charge overnight, and why it waits before it starts.
Read the guide →Are heat pumps worth it? The real 2026 numbers
Electricity costs 3.3x gas per kWh. A heat pump is about 3x as efficient. The numbers nearly cancel out.
Read the guide →Why the best export rates always carry conditions
The top export rates are acquisition offers. Here is how to price the condition.
Read the guide →G98 or G99: which one applies, what the application involves, and how long it takes
The G98 line sits at 3.68kW per phase. Above it, your network operator has to say yes first.
Read the guide →Get my free quote
Takes about two minutes. We call or text within one working day to book your free 30-minute video design call at a time that suits you. We design it around your roof and your numbers, and our MCS-certified, fully insured installation teams install it.