Evidently most solar systems have no moving parts and are expected to cost very little to maintain - but ensuring that dust is washed off, and carrying out the occasional electrical check, should be recognised as essential. Compared with flat roofs, sloping roofs may be more able to rely upon rain-washing for a year or two, but sooner or later they will also require a thorough clean - and this is not necessarily a job for your local window cleaners, since access and working at height may pose safety risks, not to mention having water and direct-current electricity in close proximity.
Such secondary "operations and maintenance" services for solar systems are really the realm of specialist PV contractors like NFU Approved Supplier BeBa Energy, who can carry out remote monitoring (to detect any drop-off in performance) as well as periodic checks for electrical safety and possible physical damage (including that from vermin or livestock).
The NFU headquarters Conference Centre at Stoneleigh Park has an almost-flat 36-kilowatt rooftop system that meets up to half the electrical needs of the building. Installed in 2012, it was overdue for a service - and we were pleasantly surprised at the results, including improved electricity generation, which resulted from BeBa's "deep clean" of the solar modules using a specialist rotary brush cleaning system. A number of minor electrical faults were also detected and are being corrected to bring it back into optimal working condition.
For a few hundred pounds, a medium-sized agricultural rooftop solar system can be cleaned, inspected and checked - money quickly recouped by avoiding the likely decline in output as dirt and faults accumulate over the years. Until the end of June, BeBa are offering a free 'health check' and condition report for NFU members with systems over 30 kW - contact them on 01442 220100