Is your roof ready for solar? Five checks before a survey

A solar array will sit on your roof for 25 years or more. Before anyone designs one, it is worth knowing whether the roof will last that long and whether it can carry the load. These are the five things our engineers look at first. You can check most of them yourself.

1. Age and condition

If the roof covering is due for replacement within ten years, replace it first. Lifting and refitting an array costs far more than doing the roof before installation. Look for ponding water, blistering on bitumen roofs and corrosion on sheet metal, and find out when the roof was last renewed.

2. Structure and load

A ballasted east-west system on a flat roof adds 12 to 20 kg per square metre. Most warehouses built after 2000 have that margin; older buildings and lightweight roofs may not. The original structural drawings answer the question quickly, so find them before the survey if you can.

3. Shading and obstacles

Rooflights, plant, parapets, chimneys and neighbouring buildings all cast shade. Shade on one panel can pull down a whole string, so we model every obstacle over a full year. A roof full of rooflights still works; it just carries fewer panels.

4. Access and fire safety

Installers need safe access, and fire services need clear routes across the roof and isolation points they can find. We design walkways and keep distances from fire walls and smoke vents. Your insurer may have its own rules, so tell them early.

5. Electrical room and grid connection

The array connects into your main switchboard. We check that the board has space and capacity, and that your grid connection can accept the power you will export at midday. Where it cannot, a battery or export limit solves it.