How often should commercial solar panels be cleaned? A Maintenance Guide

Most commercial solar Photovoltaic (PV) systems need cleaning at least once or twice a year to optimise energy production.

It is a common misconception that solar panels are maintenance-free because they don’t have any moving parts and relying on rainwater to keep panels clean throughout the year is a costly operational mistake. While the wet weather can wash away light dust and soiling, it is not sufficient enough to remove any sun-baked residue or bird droppings for example.

However, commercial cleaning schedules depend entirely on a site’s immediate environmental conditions, roof pitch and local surroundings.

For standard commercial sites situated on suburban office parks or commercial retail units for example, a bi-annual or annual maintenance schedule is usually sufficient. This regular servicing clears seasonal grime, pollen and winter organic buildup.

High-soiling and industrial sites require a more frequent quarterly cleaning schedule. This higher frequency is essential for commercial systems operating near agricultural land where airborne soil accumulates, near manufacturing hubs with chemical fallout, along busy transport depots or in coastal regions where salt spray leaves deposits on the glass.

Solar PV panels work by converting sunlight directly into usable electricity. When dirt, grime, and environmental residue collect on the glass face, they block light.

Over time, airborne dust, bird droppings, heavy traffic soot, lichen and industrial fallout can build up on the surface of panels. This creates a permanent light barrier, known in the renewable industry as soiling loss, that can reduce your commercial energy yield by up to 25%. For a business relying on solar power to cut operational overheads and meet corporate sustainability targets, that uncaptured energy translates directly into thousands of pounds in higher grid energy bills.

However, output loss is only part of the problem. Uncleaned debris creates localised micro-shading on individual panels. When a cell is shaded while surrounding cells generate full power, the shaded cell acts as a bottleneck, causing localised cell heating – also known as thermal hot spots.

If hot spots are left unchecked, extreme heat can permanently burn out internal PV cells and increase fire hazards on commercial rooftops. Just a 15% drop in system efficiency forces your business to buy expensive electricity back from the National Grid. Ignoring minor soiling quickly escalates into major equipment failure and premature system replacement.

From schools and hospitals to warehouses, offices and retail parks – commercial roofs come in all different shapes, sizes and heights. For this reason there are a variety of access methods and cleaning equipment that can be selected for the job.

• Water-fed pole systems – For solar panel systems that can be accessed from the ground or low-rise roofs, water-fed pole systems are available. This system has an extendable pole that technicians can use from the ground without having to climb on to the roof, allowing the panels to be cleaned with purified water and the soft bristles.

• Scaffolding and Mobile Elevated Work Platforms (MEWPS) – If access is required for a number of days or on large and complex sites, access can be gained by certified technicians via the use of scaffolding or powered access equipment such as scissor lifts or cherry pickers.

• Abseiling – To avoid the need for scaffolding or where roofs may be hard to reach or steep, rope access can be a suitable alternative for trained technicians with IRATA certification.

• Drone and robotic cleaning systems – These systems represent the cutting edge of solar panel maintenance technology. With the ability to cover large surface areas, quickly and without having to access the roof via a technician they provide the safest method of cleaning.

At SCJ Renewables we use a combination of methods, utilising our own specialised equipment via our trained and certified technicians.

To guarantee long-term performance and high efficiency, commercial solar systems require proactive operation and maintenance support.

An operation and maintenance package combines regular cleaning with thorough system inspections and diagnostics.

During scheduled maintenance visits, you can expect highly skilled and trained technicians to perform a health check including:

• Visual inspections – for physical damage, discolouration, debris or loose mounting
• Thermal imaging – Scans for invisible thermal hot spots, loose connections and micro cracks before they cause failure
• Electrical and safety testing – Tests string voltages, inverter health, isolators, cabling and earthing to ensure full safety compliance
• Structure checks – Inspects roof mounting system and frames to ensure stability against high winds
• Inverter checks and servicing

On completion of a maintenance visit you should then be supplied with follow up performance reports and documentation confirming what checks and maintenance was carried out. Keeping this documentation on record is important to ensure warranties remain intact.

Solar panels are a long-term investment, and like any asset they perform best with the right care.

As with any solar installation, maintenance frequency is not a one-size-fits-all approach, with many variables such as system type, location and environment affecting how cleaning and maintenance of your solar panels should be applied.

SCJ Renewables is one of the North East’s leading solar PV installers, specialising in projects of all sizes with industrial and commercial clients.