Solar panels for UK homes, explained properly

Most UK pitched roofs can take solar panels. The questions that decide it are how much unshaded roof area you have, which direction the roof faces, the pitch, and the condition of the roof covering. Tile, slate and metal roofs are all routinely used; older or damaged coverings sometimes need attention before an array is fixed to them.

Complex roofs with dormers, valleys, hips and multiple small faces can still work well, but the usable area is always smaller than the total roof area. Vents, flues, aerials, rooflights and the clearances required at ridges, verges and eaves all reduce what can actually be filled with panels.

Satellite roof data tells you the maximum number of panels that could physically fit in your usable roof area. That is a measurement, not a recommendation. The right system size is a design decision that also depends on how much electricity your household uses each year, how much of your generation you would use in the home rather than export, whether you are adding a battery, and the inverter and grid connection design.

This is why a recommended system is frequently smaller than the roof's physical ceiling. Filling a roof with panels whose output you rarely use is not automatically better value. Every figure we show you is labelled as one or the other, so it is always clear which you are looking at.

South-facing roofs give the highest annual yield in the UK, but they are not a requirement. East and west roofs typically generate somewhat less over a year while spreading generation across the morning and late afternoon, which can match household usage better. North-facing roofs are generally not worth using in the UK.

Pitch matters less than direction. Most UK domestic pitches sit in a range that works perfectly well. Shading matters more than either: even partial shade across part of an array at midday has a disproportionate effect, which is why shading is assessed per roof face rather than for the property as a whole.

Generation is usually described in kWh per year for each kWp of installed capacity. In the UK that figure varies with location, roof direction, pitch and shading, so it is only meaningful when it is calculated for a specific roof. Our assessment uses solar irradiance data for your own property rather than a national average.

Output follows the seasons: strongest between roughly April and September, noticeably lower in December and January. Panels generate from daylight rather than heat, so cold bright days can be very productive. What you save from that generation depends on your consumption pattern and tariff, not on generation alone.

Modern domestic panels are typically monocrystalline modules in the region of 400 W and upwards. The differences that matter between products are efficiency per square metre, performance under shade and higher temperatures, the product and performance warranty terms, and physical dimensions, which determine how many panels fit a given roof face.

The inverter converts DC generation into the AC electricity your home uses, and its sizing relative to the array affects both performance and your grid connection paperwork. Mounting systems are chosen to suit the roof covering: on-roof rails and hooks for tiles and slates, with in-roof options where a flush appearance is preferred.

Panels are long-life equipment with no moving parts. Manufacturers typically warrant performance for decades with a small annual degradation allowance, so an array continues to generate well beyond its payback period. Inverters are the component most likely to need replacing within the system's life.

Maintenance is minimal. UK rainfall keeps most roof-mounted arrays reasonably clean; monitoring is what actually protects your investment, because it shows generation falling off before you would ever notice it on a bill.