Drone-based Solar Panel Cleaning

What we looked at first

On rooftop sites the problem is not the cleaning. It is having people on the roof at all. So the first question we asked was whether anyone needs to go up there, not how to wash more thoroughly.

Tethered water supply is the answer to that question. With no tank aboard, the weight and endurance limits loosen; the cost is that working range is bounded by hose length. That trade holds on rooftop sites. On large ground-mounted farms it may not.

Why cleaning matters

Dust on solar panels eats directly into output. Rooftop sites in Taiwan have a second problem: humidity and bird droppings let moss and algae take hold between the cell grid lines, and rain does not wash that off.

The conventional approach sends people onto the roof to drag a hose and scrub panel by panel. The roof pitch, the wet panel surface and the microcracks that footsteps can cause are all risks at once.

How we do it

We spray from a drone. Nobody goes onto the roof.

The aircraft carries the spray head　A quadcopter hovers low over the panels and directs a pressurised jet downward.

A tether supplies the water　Water is pumped from ground-level storage up a hose to the aircraft. This is the design that makes it work. If the aircraft had to carry its own water, the payload would destroy endurance and the area covered per flight would be tiny. Tethered, the working time is limited only by the supply on the ground.

Flying close to the surface　The aircraft holds a low altitude above the panels so the jet retains enough force to lift what is stuck to them. That calls for stable hovering on a rooftop, where GPS support is often marginal.

What the video shows

The first segment is the wide view of the work in progress. You can see the jet leaving the underside of the aircraft, the supply hose trailing behind it and, most tellingly, that the panels the aircraft has already passed are dark and wet while those ahead of it are still pale and dusty. The progress line is visible in the frame.

The second segment is shot close in. Green growth is clearly visible between the grid lines on the unwashed panels, and the surface returns to clean dark glass as the jet sweeps across.

Before and after

A drone working above a rooftop solar array with a visible water jet beneath it; panels to the left are washed and dark, panels to the right are still pale with dust. — Work in progress. The jet is visible directly beneath the aircraft. Panels to the left have been cleaned and are dark; those to the right are still pale with dust, and the boundary between them is unmistakable. The white container at bottom left is the ground water supply.

Close-up of panel washing: the lower panels are covered in green growth between the grid lines, the upper panels have been washed clean. — The same contrast up close. On the unwashed panels below, green growth fills the space between the grid lines. Above, the jet has restored the surface to clean dark glass. Rain does not shift deposits like these.

More detail

Site scale, throughput and pricing are quoted after assessing the conditions on site. Please get in touch through the contact form.