Bird Droppings on Solar Panels: Why They Cut Output and How to Remove Them

A single bird dropping looks harmless on a large solar panel. But unlike uniform dust, droppings create small, dense patches of shade that can pull down the output of a whole string of panels and, over time, create hot spots. Here is why they matter, how to remove them safely, and how to keep birds away.

Why a small dropping causes a big loss

Solar cells in a module are connected in series, and modules are connected in series in a string. When one cell is shaded, it can no longer carry the same current as its neighbours. The module’s bypass diodes switch on to route current around the affected section, which means that whole section of the module stops contributing. A dropping covering part of just one cell can therefore reduce the output of a far larger area than the dropping itself.

The hot spot risk

If a shaded cell is forced to carry current, it can heat up well above its neighbours. These hot spots can discolour the cell, damage the backsheet and, over time, permanently reduce the module’s output. A thermal (infrared) inspection will show hot spots as bright points; they often line up with droppings, leaves or cracks.

How to remove bird droppings safely

1. Remove them early. Fresh droppings often come off with a soft dry brush.
2. For dried droppings, soften them with a lightly damp soft cloth or sponge for a minute, then wipe gently.
3. Never scrape with a blade, scrubber or abrasive pad. It will scratch the anti-reflective coating.
4. Avoid harsh chemicals and detergents; check your module manufacturer’s guidance.
5. Work at a cool time of day, never on hot glass at midday.
6. Never walk on the panels. Use a telescopic tool from a safe position.

A long-handled dry cleaner such as Aqualess is useful for reaching panels in the middle of a rooftop array without climbing onto the structure.

How frequent cleaning helps

Daily or regular dry cleaning by a robot such as Solar Glide removes many fresh droppings before they dry and bake on, and keeps the rest of the panel clean so remaining spots are easy to see and treat.

Keeping birds away

• Remove food and water sources near the array.
• Install bird mesh or skirts around the edges of rooftop arrays to stop pigeons nesting underneath the panels.
• Use bird spikes on parapets and nearby perches.
• Visual deterrents such as reflective tape or decoys work best when moved regularly.
• Use humane methods, and check local regulations about protected species.

Frequently asked questions

Can rain wash off bird droppings?

Heavy rain sometimes softens and removes them, but dried droppings usually need gentle manual cleaning.

How do I know if droppings have caused damage?

Look for brown or burnt-looking spots on cells, or ask a technician for a thermal scan to check for hot spots.

Questions about keeping your panels clean? Contact MROBOTICS.