How does the installation of solar panels affect the durability of the roof?

Installing solar panels is an increasingly popular way to generate renewable energy and cut electricity bills, but it does affect the roof it sits on. Done professionally, on a roof that is in good condition, solar panels are not likely to damage the roof and can even protect it. Done carelessly, or on a roof that was not ready for them, they can shorten its life.

How solar panels affect the roof

• Extra weight: panels add load to the roof structure. Most roofs built to current standards can carry this, but older buildings may need their structures checked or reinforced first.
• Fastening points: most mounting systems need holes drilled into the roof to anchor the rails or hooks. If these penetrations are not sealed properly, they can weaken the roof's waterproofing and lead to leaks, moisture damage or mould under the roof over time.
• Wind and weather loads: the mounting system has to keep the panels firmly in place in wind and snow, without loosening the roof covering underneath.
• Protection from the elements: panels also shield the section of roof under them from direct sun, rain and snow, which can reduce wear on that part of the covering and, in some cases, extend its life.
• Maintenance access: panels can make it harder to inspect and maintain the roof if they cover it edge to edge, so it is worth leaving access routes for future checks and repairs.

How to avoid damage

The risks above are all manageable with the right preparation:

• Use an experienced, certified installer who can assess the roof's condition and confirm it is ready for panels before work starts.
• Check the condition of the roof beforehand and make any needed repairs first, rather than installing panels over a roof that already needs work.
• Choose a mounting method suited to the roof type; some methods, such as rail systems that spread the load, put less strain on the structure than others.
• Use quality fastening systems and make sure every roof penetration is sealed correctly.
• Plan for maintenance access, for example by leaving service routes between rows of panels.

In short, professionally installed solar panels on a roof that is sound to begin with do not typically shorten its life, and can even add a degree of protection. The risk of damage comes mainly from installing on a roof that was not ready, or from installation work that is done carelessly.