Solar suitability check: what an early screen can tell you

What an early screen is for

However, an early screen is a first filter. It helps you decide whether solar is worth a proper conversation. It does not design a system, and it should never be treated as approval.

Our browser-based solar suitability checker on the home page asks about your property type, roof shape, direction and visible shading. It runs in your browser. The result is deliberately loose, because a few answers cannot support precise claims.

So treat the result as a prompt. If it says your home looks promising, you have a reason to gather quotes. If it raises doubts, you have a list of things to ask about.

What the check covers

In practice, four inputs do most of the early work. Each one changes how much power a roof can make, and each is easy to judge from the ground.

• Property type. A detached house, a terrace and a flat raise different questions about access, ownership and roof space.
• Roof form. A simple pitched roof is easier to fit than one with many hips, dormers and valleys.
• Direction. South-facing roofs usually yield most. East and west roofs still produce well. Our guide to east and west facing solar panels explains the trade-offs.
• Visible shading. Trees, chimneys and nearby buildings all cut output. Shade matters most in winter, when the sun is low.

Location matters too, because sunshine differs across Britain. The European Commission’s PVGIS tool estimates solar output for any place.

For example, a 1 kWp system facing south at 35 degrees makes around 1,025 kWh a year in Bristol. In Glasgow it makes around 853 kWh. Those figures assume a default 14% system loss. Your own roof will differ, so a survey should always give you a figure for your home.

What it cannot see

This is the important part, because many key details are invisible from a screen or a street.

MCS is the quality scheme for small-scale solar in the UK. Its installation standard, MIS 3002 version 6.0, says a competent person must check the roof structure for the extra load. An online tool cannot do that.

Only a survey can settle these points. A screen cannot see them:

• The strength of the rafters and the state of the roof covering.
• The exact size and angle of each roof face.
• The space and capacity of your fuse board and meter.
• The safest route for cables, and where the inverter can go.
• Whether the roof has asbestos, which needs specialist handling.
• Access for scaffolding and for fire crews.
• Planning limits that apply to your home.
• Any rules set by your electricity network.

Since 18 June 2026, MCS installers must also give evidence for the mounting system. This includes structural and wind loading calculations where no certified mounting system is available. That is a good document to ask for.

Planning and permissions

Most roof panels in England do not need a planning application. However, the rules changed in August 2026. The government amended permitted development rights on 27 August 2026, and the new rules treat houses and blocks of flats differently. Projects that no longer qualify can use the old rules until 26 August 2027, according to the Planning Portal.

Because the details have changed, check the current limits on the Planning Portal’s solar page rather than relying on older advice. Rules in Scotland and Wales differ again. Listed buildings and conservation areas always need extra care, and leasehold homes may need your landlord’s consent.

A good installer should raise these points at the survey. Also, because rules differ by area, you can ask your local council’s planning team before you commit.

Judging the size you might need

An early screen can hint at how many panels fit, but it cannot say how many you need. That depends on how you use power, since use sets the target size. Ofgem’s typical use figure for a medium household is 2,500 kWh a year from 1 July 2026. Your own bills may be higher or lower.

Our guide on how many solar panels you need explains how to match system size to your use. In short, a bigger system is not always a better one. Roof space, budget and daytime use all set the limit.

Then comes cost, because it decides whether the idea is worth pursuing. Our solar panel costs guide sets out what the government’s own data shows. Treat any price that comes from a screen as a rough guide only.

Use the result well

Instead of a verdict, treat it as a starting list of questions. Here is a simple way to use it.

1. Write down every point the check raised, such as shade, roof shape or a flat roof.
2. Note anything it could not judge, such as the fuse board.
3. Take photos of your roof from the ground, and of your meter and fuse board.
4. Ask at least two installers how their final design deals with each point.

Next, get ready for the visit itself. Our guide to preparing for a survey lists the documents and energy data worth having to hand. When you are ready to compare firms, you can request quotes through our enquiry form. Nobody is contacted until you choose to send an enquiry.

When the early picture is wrong

Although the screen may look good, the survey sometimes says no. That is normal, and it is not a sign of a bad installer. The survey has more evidence than you gave the screen.

Common reasons include a weak roof structure, heavy shading that was hard to see, or too little room at the fuse board. Equally, a roof that looked poor can turn out better than expected. A good installer will explain the finding and show their working.

Finally, be wary of anyone who skips the survey and promises a price from a photo alone. A design built on guesses causes disputes later, because nobody checked the roof.

Keep expectations calm

Overall, solar can be a sound investment for the right home. It can also be a poor fit for the wrong one. An independent screen is only useful if you let it say “maybe” or “no”.

Take your time. So compare more than one design, keep every document, and ask for assumptions in writing. The aim is a system that suits your roof and your habits, not a quick sale.