"Will it actually generate anything up here?" is the first question almost every Bradford homeowner asks, and it is usually asked about the wrong variable. People worry about being in the north. The number that decides their output is which way the roof points, and the gap between the two is larger than most quotations admit.
This article does two things. It gives the modelled annual output for a Bradford roof using a public tool you can re-run yourself, with the setting stated explicitly, and it explains why the figure on your MCS performance estimate will not match it — and which of the two you should actually hold your installer to.
The number for a Bradford roof, and the setting that changes it
PVGIS is the European Commission’s photovoltaic performance tool and the usual public reference point. For a Bradford location at 53.796°N, 1.759°W (elevation 127m), using PVGIS 5.3 with the PVGIS-SARAH3 radiation database covering 2005–2023, a 4kWp crystalline silicon array, 14 per cent system losses, a 35° pitch and due south orientation, the modelled annual output is 3,633 kWh. That is 908 kWh per kWp installed.
Now the setting that matters, and that almost nobody states. PVGIS asks you to choose a mounting position: building-integrated or free-standing. Run exactly the same inputs as free-standing and the answer rises to 3,739 kWh, or 935 kWh/kWp — 2.9 per cent higher. The difference is temperature. A free-standing array has air moving behind it, runs cooler and therefore converts slightly more of the same irradiance. Panels on battens a few inches above a Bradford slate roof do not get that airflow.
So 3,633 kWh is the honest figure for a house, and 3,739 kWh is the figure you get if you quietly leave the tool on the wrong setting. It is only a hundred kilowatt-hours, but it is a hundred kilowatt-hours in the direction that flatters the quote, every year for twenty-five years. If a generation estimate looks optimistic, the mounting setting is the first place to look.
Orientation beats latitude, and not by a small margin
Here is the same Bradford array, same 35° pitch, same roof-mounted setting, turned through the compass.
| Orientation | Annual output (4kWp) | Against due south |
|---|---|---|
| South | 3,633 kWh | — |
| South-east | 3,429 kWh | −5.6% |
| South-west | 3,412 kWh | −6.1% |
| East | 2,896 kWh | −20.3% |
| West | 2,875 kWh | −20.9% |
| North | 1,993 kWh | −45.1% |
Compare that with the latitude penalty everyone frets about. Run the identical array, roof-mounted at 35° due south, in London and PVGIS returns 3,950 kWh. In Plymouth, about as favourable as mainland Britain gets, it returns 4,351 kWh. So Bradford gives up 8.0 per cent against London and 16.5 per cent against Plymouth.
Read those two sets of numbers together and the conclusion is blunt: turning your Bradford array from south to east costs 20.3 per cent, which is more than the entire latitude gap between Bradford and Plymouth. Put another way, a south-facing Bradford roof produces 3,633 kWh while an east-facing London roof produces 3,182 kWh. The Bradford roof wins by 14 per cent. Being 170 miles further north matters far less than being 90 degrees off south.
There is a local footnote worth having. The same array modelled at Hemsworth, 25 miles east on the other side of the Pennine edge, returns 3,781 kWh — about 4 per cent more than Bradford, and more than Leeds at 3,680 kWh. Bradford sits on the western rim of West Yorkshire and gets slightly more cloud for it. It is a real effect, and it is still an order of magnitude smaller than orientation.
Pitch is the variable you can stop worrying about
Same Bradford location, same roof-mounted setting, due south, varying only the pitch:
- Flat, 0°: 3,027 kWh (−16.7% against the optimum)
- 15°: 3,395 kWh
- 20°: 3,482 kWh
- 30°: 3,603 kWh
- 35°: 3,633 kWh
- 40°: 3,644 kWh — PVGIS returns 40° as the optimum inclination for this location
- 45°: 3,635 kWh
- 60°: 3,493 kWh
Everything between 30° and 45° lands within 1.2 per cent of the optimum. Most Bradford pitched roofs — the stone terraces, the inter-war semis, the gabled through-terraces — sit inside that band already. Unless you are looking at a genuinely shallow roof or a flat roof needing tilt frames, pitch is not a number that should change your decision.
Why your MCS estimate will not say 3,633 kWh
An MCS-certified installer does not quote you a PVGIS figure. The MCS standard estimation method works differently: estimated annual output is the array’s rated capacity in kWp, multiplied by a Kk value, multiplied by a shade factor. The Kk value is read from an MCS irradiance table and depends on the array’s pitch, its orientation and its location, which is matched from the postcode to one of MCS’s zones. The shade factor runs from 1 for a completely unshaded array down to 0 for a fully shaded one.
Two things follow, and installers should be straight about both. First, the method is not reproducible from a public tool. MCS does not publish its Kk tables openly — we checked the current solar PV installation standard, MIS 3002:2025 Issue 1.0, and the Kk tables and the estimation method are not in that document; they sit in MCS’s separate performance-estimate material. So you cannot independently recreate the number on your quotation, which is precisely why you should ask for its inputs rather than its output.
Second, the MCS figure will usually land below a bare PVGIS run for the same roof, and that is correct behaviour rather than pessimism. PVGIS’s default run models the terrain horizon — the Bradford figures above use a digital elevation model for exactly that — but it knows nothing about your chimney stack, your dormer, the gable end of next door, or the sycamore in the back garden. The shade factor is where all of that lands.
What to ask for, in one line: show me the Kk value, the shade factor and the resulting kWh as three separate numbers, and tell me which MCS document and version produced them. An installer who can answer that has done the design. One who can only produce a single round annual figure has done a guess.
Shading is the Bradford-specific variable
Bradford’s terraces climb and traverse steep valley sides, which produces a shading pattern you do not get on a flat suburban estate. The terrace one row up the hill can clip the winter sun off the row below. Tall stone gable ends and the city’s characteristically large chimney stacks throw long shadows across neighbouring roof planes in the exact months when generation is already thin.
This is why the shade factor deserves more of your attention than the postcode zone. The zone is fixed and modest in its effect; shading on a specific Bradford roof can take a double-digit percentage off the annual figure, and it is the one input that a proper on-roof or drone survey can actually establish. Optimisers or micro-inverters change how badly a shaded string behaves, but they do not remove the shade — they limit the damage it does to the unshaded panels.
What those kilowatt-hours are worth
Generation is only half the arithmetic. Under the Ofgem energy price cap for 1 October to 31 December 2026, the national average electricity unit rate for a direct debit customer is 26.32p per kWh, with a daily standing charge of 54.83p. A kilowatt-hour you use in the house as it is generated is worth that unit rate. A kilowatt-hour you export earns whatever Smart Export Guarantee rate your supplier offers, and suppliers set those rates themselves — Ofgem sets the eligibility rules, not the price. So the same 3,633 kWh is worth materially different amounts to a household that is in all day and one that is out until six.
Two dated points on cost worth knowing. The zero rate of VAT on installing energy-saving materials runs to 31 March 2027, after which it reverts to the reduced rate of 5 per cent; it applies to residential accommodation, not commercial premises. And Smart Export Guarantee eligibility requires the installation to be certified under MCS or an equivalent scheme, which is a practical reason not to use an uncertified installer however keen the price looks.
The short version
A south-facing Bradford roof at a normal pitch should model at roughly 900 kWh per kWp installed on the roof-mounted setting, so about 3,600 kWh from a typical 4kWp array before shading. Latitude costs you single-digit percentages. Orientation costs you up to twenty. Shading is the variable that decides whether your roof is at the top or the bottom of its range, and the only way to pin it down is to survey it.
If you want the system sizing, equipment options and installation detail for this area, our page on solar panels Bradford is the place to start. To see how the generation figure feeds into a payback calculation, our guide to solar panel payback periods walks through the arithmetic.
Or, if you would rather have the Kk value, the shade factor and the modelled output for your own roof rather than a county average, that is what a Bradford roof survey produces.