Systems and kit
Panels, inverters, and what the roof will actually take
We fit four array sizes on most jobs and specify from a short list of parts we can still service in fifteen years. Everything below is the standard specification; anything else is a written variation before work starts.
Array sizes
Four sizes, and the roof each one needs
Array
Panels
Roof area
Typical year
Typical install, GBP
3.5 kWp
8
16 m2
4,900 kWh
5,800
5.0 kWp
11
21 m2
7,000 kWh
7,600
6.5 kWp
15
29 m2
9,100 kWh
9,400
8.0 kWp
18
35 m2
11,200 kWh
11,300
Panel counts assume 440 W modules and typical year assumes 1,400 kWh per kWp, which is a southern figure. Install prices are indicative for a two-storey pitched roof with no access problem and exclude scaffolding on more than one elevation.
The parts list
What we specify, and why that part
Panels
Monocrystalline, 440 W, all-black frame
Twenty-five year product warranty, not just performance
Degradation clause at or under 0.5 percent a year
IEC 61215 and 61730, wind and snow rated for exposed sites
Inverters
String inverters with a UK service presence
Ten year warranty as standard, extendable to fifteen
Optimisers only on strings a shading survey says need them
Replacement budgeted at year thirteen in every quote
Mounting
On-roof rail, or in-roof tray where planning says so
A15 rated hooks, stainless fixings, no roof penetration on flat
In-roof trays on listed and conservation work
Bird protection to the array perimeter as standard
Cover
Three warranties, three different lengths
They are not the same document and they do not expire together. This is the part of a solar quote most likely to be summarised into one meaningless number.
Panel product warranty
Covers the panel itself against defect, not its output. Claimed against the manufacturer, and worth exactly what that manufacturer is still worth in year twenty.
25 years
Panel performance warranty
Guarantees a minimum percentage of rated output each year, typically 87 percent by year twenty-five. This is the clause the degradation figure comes from.
25 years, sliding
Inverter warranty
The short one, and the reason a replacement is budgeted in the payback model rather than hoped for.
10 years, extendable
Workmanship
Ours. Covers the mount, the penetrations, the wiring and the making good. MCS requires it and we do not shorten it.
5 years
Next step
Ask what we would put on your roof
Send a photograph of the elevation and a postcode. We will tell you which of the four sizes fits and which mounting method the covering needs.