After months of grey skies and persistent rain, the longer days are finally here. For facilities managers responsible for commercial and industrial buildings with solar installations, that shift in the weather represents a significant opportunity – but only if the panels are ready to make the most of it.
The irony of solar energy in the UK is that the season when panels can perform at their best is also the season that follows months of rainfall, wind, and biological growth. Moss, algae, bird droppings, leaf debris and winter grime all accumulate over the colder months. By the time the sun arrives in earnest, many panels are operating well below their rated output – and the lost generation is rarely recovered.
The performance gap is real
Soiling and debris on solar panels can reduce energy output by as much as 20-30%, depending on the extent of the build-up and the environment. For commercial and industrial installations – where solar is increasingly embedded in wider energy management strategies – that represents a measurable financial shortfall, not just an efficiency footnote.
There is also a compliance dimension that is easy to overlook. Many panel manufacturers include regular professional cleaning as a condition of their warranty. Without documented evidence of maintenance, operators may find warranty claims complicated or rejected outright. For FM teams managing multi-site estates, keeping that documentation in order matters.
More than just a clean
NSS Group, a specialist services company and part of PTSG, introduced a new service to its portfolio earlier this year, providing professional solar panel cleaning for commercial, industrial and large-scale installations across the UK. The service uses purified water systems with soft-bristle brushes – no chemicals that could degrade panel coatings or void warranties – and is carried out entirely by directly employed operatives trained to work safely at height.
Alongside the clean itself, NSS provides full photographic documentation before, during, and after each visit, along with inspection reporting that flags any issues affecting performance. For FM teams with reporting obligations or contract KPIs, that paper trail has practical value beyond the cleaning itself.
The service can also be coordinated alongside electrical testing for a complete performance check in a single planned visit – with specialist engineers attending for each discipline – useful for teams looking to consolidate maintenance activity and reduce access costs.
Planning ahead
For most installations, professional cleaning every six to twelve months is sufficient to maintain performance – though sites in high-pollution areas, or those with significant tree coverage or bird activity, may benefit from more frequent attention. The start of the productive season is a logical point to schedule a clean: panels are brought up to full efficiency before peak generation and any issues identified during inspection can be addressed before they develop further.
NSS operates with 24/7 call-out availability and national coverage and uses no subcontractors – meaning the same standards apply regardless of location. Access platforms and safety equipment are included as standard.
With energy costs still a live concern for most estates and sustainability commitments increasingly tied to measurable output, getting the most from an existing solar installation is sound practice. A professional clean at the start of the summer period is one of the more straightforward ways to do it.
For more information on NSS Group’s solar panel cleaning service, visit nssgroup.com or call 03459 677477.
Proud to be part of www.ptsg.co.uk
