Solar PV Panels
The panels are the visible part and the least interesting one. What decides your output is where they go, how they are wired and what the roof does to them across a day.
0% VAT until 31 March 2027 • MCS-certified installation • DNO notification handled
Eighteen identical panels, wired as two strings. Which panel sits in which string is the part that decides what the array does on an overcast February afternoon — and it is decided after the shading survey, not before it.
Approved installers — accreditations held by Qualis Energy Limited
Filling a roof is easy. Filling it well is the job
Filling a roof is easy. Filling it well is the job
Most solar quotes are a packing exercise: count the tiles, count the panels, print the number. A well-designed array is a different piece of work. Strings are planned around shading measured through the day rather than guessed at from the pavement, the array is kept clear of the roof edges where wind uplift is highest, and there is room left to work if a panel ever has to come off.
Roof penetrations are flashed and weathered properly. Panels will be up there for twenty-five years or more, so if the roof underneath has only a few years left in it we will tell you before we fix rails to it — not after.
Mounting options
Four ways an array gets fixed to a building, and what each one costs you in money, tidiness and access.
- On-roof — rails fixed to the rafters through flashed penetrations, panels sitting above the tiles or slates. The standard approach: quickest, cheapest, and the ventilation gap behind the panels helps them run cool.
- In-roof — panels set into the roof plane in place of tiles, with a proprietary tray system underneath. Noticeably tidier, usually preferred on new build and often the route to consent in a conservation area. It costs more and runs slightly warmer.
- Flat roof — ballasted A-frames or east-west “butterfly” layouts. No penetrations, but the wind loading calculation matters and so does whether the roof can carry the ballast.
- Ground-mounted — where there is land and the roof is wrong. Better access for cleaning and maintenance, ideal orientation, but a trench, a longer cable run and, above a certain size, a planning application.
The three things that actually move the number
Orientation and pitch, measured shading, and what the planning system permits.
Orientation, pitch and what they are actually worth
South-facing at around 35° gives the highest annual total. That is not the same as the best system for your house. An east–west split array generates across the morning and the evening rather than piling everything into the middle of the day, and if the house is empty from nine until six that shape of generation is often worth more to you than a bigger midday peak you export at seven pence.
We model your specific roof — orientation, pitch, location and measured shading — using the standard MCS methodology, and give you an annual kWh estimate alongside a self-consumption estimate. The second number is the one that decides your bill.
Shading, strings and optimisers
Panels in a string behave a little like a row of taps on one pipe. Shade one and you can drag down everything wired with it. Chimneys, dormers, aerials, satellite dishes, flues and the neighbour’s sycamore all do this, and they do it at different times of day and different times of year.
Two things follow. First, string layout is a design decision that should be made after the shading survey, not before. Second, optimisers — per-panel electronics that stop one shaded module dragging its neighbours down — genuinely earn their money on some roofs and are sold as a default upsell on plenty of others. We will tell you which of the two you are looking at, and why.
Planning permission
Most domestic roof-mounted solar in England falls under permitted development, subject to conditions on how far the array projects and where it sits. Listed buildings, conservation areas, flats and larger ground-mounted arrays are the common exceptions. We flag anything we spot at survey, but the final position rests with your local planning authority.
Specification, protection and honest limits
What we fit, what we do to keep it working, and what an array without storage will not do for you.
We specify tier-one monocrystalline modules with full-black framing where appearance matters, and we choose on warranty terms and degradation rate rather than headline efficiency. A panel that is half a percent more efficient on a datasheet is worth far less than a string that is not shaded at two o’clock in October.
Product ranges change frequently, so rather than pin this page to a model number we will put the exact modules, inverter and mounting system in your written proposal, with the datasheets attached.
Pigeons nest under arrays and make a mess that is cheap to prevent and expensive to fix. Where they are a known local problem we mesh the array perimeter at installation. It is worth asking any installer whether their quote includes it.
An array with no storage typically means you use somewhere around a quarter to a third of what you generate and export the rest, and exported power earns a fraction of what it costs to buy back. That can still be a sound investment — particularly if someone is home during the day — but it is why we ask about your evenings before we count panels. Battery storage is what moves that figure, and an EV charger moves it again.
FAQs
Do I need planning permission for solar panels? +
Most domestic roof-mounted solar in England falls under permitted development, subject to conditions on how far the array projects from the roof plane and where it sits. Listed buildings, conservation areas and World Heritage sites are the exceptions, and in-roof mounting is often the route to approval in those cases. We check the constraints for your property at survey stage and tell you before you commit.
On-roof or in-roof — which should I choose? +
On-roof is quicker, cheaper and the standard approach: rails fixed to the rafters through flashed penetrations, panels sitting above the tiles. In-roof sets the panels into the roof plane in place of tiles and is noticeably tidier, which is usually what decides it — that, or a conservation officer.
Will one shaded panel really affect the whole array? +
It can. Panels wired in series behave a little like taps on one pipe, so shade on one module can drag down everything in that string. That is why string layout follows the shading survey, and why we fit optimisers where the geometry genuinely calls for them rather than as a line on every quote.
Which panels do you install? +
Tier-one monocrystalline modules, with full-black framing where appearance matters. We choose on warranty terms and degradation rate rather than on headline efficiency. Product ranges change often, so the exact modules, inverter and mounting system are named in your written quote rather than on this page.
Is my roof strong enough, and what if it needs work? +
Rafter condition and spacing are checked at survey. Panels are on a roof for twenty-five years or more, so if the covering underneath has only a few years left in it we will tell you before we fix rails to it — not after.
Send us the roof and the bill
A photo of the roof and your annual kWh figure is enough for us to tell you what layout is realistic, what it should generate, and whether storage changes the answer.