Brightfell, solar for houses on exposed ground
Every quote shows year one. This shows year twenty-five.
This models flat annual figures, not a half-hourly generation and consumption profile, so a real house will move off these numbers. It is an estimate built to be argued with, not a quote.
Three deductions
What a quote leaves out, in the order the money leaves
The share you never use
At the thirty percent self-consumption set in the panel above, seventy percent of what the roof makes is sold at the export rate rather than saved at the import rate. On these tariffs that is five pence against sixteen, on more than two thirds of everything the array produces.
Panels that quietly get worse
Half a percent a year sounds like nothing and compounds like something. Year twenty-five produces about eleven percent less than year one, and every one of those years is inside the payback window the brochure is quoting.
The inverter nobody quotes for
Panels are warranted for twenty-five years. Inverters are not. Budget one replacement around year thirteen, plus the annual service the warranty needs, and the second half of the payback window looks different from the first.
What we fit
Four sizes, and the roof each one needs
3.5 kWp
Panels
8
Roof area
16 m2
Typical year
4,900 kWh
5.0 kWp
Panels
11
Roof area
21 m2
Typical year
7,000 kWh
6.5 kWp
Panels
15
Roof area
29 m2
Typical year
9,100 kWh
8.0 kWp
Panels
18
Roof area
35 m2
Typical year
11,200 kWh
Panel counts assume 440 W modules. Typical year assumes 1,400 kWh per kWp, which is a generous southern figure; on the fells we survey to between 950 and 1,100 and quote on that instead.
Roofs we have been on
Every job, with the figure it actually produced
Kirkby Lonsdale, Cumbria
Hollowgate Farm
Twenty-six panels split across a barn roof and the south face of the farmhouse, sized around a milking parlour that runs through the middle of the day.
11.4
kWp
26
panels
2025
installed
Dent, Cumbria
Ravenstone Cottage
Nine panels on a listed slate roof, in-roof mounted so the array sits flush with the slate rather than standing proud of it.
4
kWp
9
panels
2025
installed
Kendal, Cumbria
Sedgewick Mill
A landlord supply feeding six flats, a lift and a communal corridor. High daytime load is what makes a system this size worth its cost.
24.2
kWp
55
panels
2024
installed
How a job runs
Five steps, and the first one is not the roof
01
Meter data first
A fortnight of half-hourly readings before anyone looks at the roof. Your consumption curve is what the array gets sized against.
02
Survey on the roof
Pitch, orientation and shading measured on site with a horizon scan, not read off aerial imagery and a postcode.
03
Design and quote
Array sized to the overlap between what you make and what you use. Both payback figures printed on the same page.
04
Install
Scaffold, mount, wire, commission. Two to four days on a domestic roof, longer where slate has to come off by hand.
05
Handover and paperwork
MCS certificate, DNO notification and your export tariff application, plus the quoted figures put beside what the meter reports.
Journal
Working notes, mostly about arithmetic
Method
/
The export rate is the whole argument
A kilowatt hour you use is worth the import rate. The same kilowatt hour sold back is worth about a third of that. Everything else in a solar quote is downstream of which pile it lands in.
Money
/
What half a percent a year does over twenty-five
Degradation is the clause every datasheet carries and no quote models. Compounded across a warranty period it removes about a ninth of the output, and it removes it from the years that matter most.
Kit
/
Choosing an inverter you can still buy in 2039
Panels outlive inverters by about a decade. The question is not which inverter is best today, it is which manufacturer will still sell you the replacement, and at what price.
Next step
A survey, then a number you can argue with
Send us a postcode and a photograph of the roof. We will tell you whether it is worth a survey before we book one, and we will say so if it is not.