Solar panels are generally self cleaning, but in particularly dry areas or where panel tilt is minimal, dust and other substances such as bird droppings can build up over time and impact on the amount electricity generated by a module. Grime and bird poop doesn’t need to cover an entire panel to have an effect.
Tips for cleaning solar panel glass
Safety first – follow the procedure in your manual for shutting down the system before commencing cleaning.
For safety reasons, it’s also wise to clean your panels from the ground if possible. A good quality soft brush and a squeegee with a plastic blade on one side and a cloth covered sponge on the other coupled with a long extension can make for the perfect tools allowing you to stay on the ground. Use a hose with a suitable nozzle to allow the stream of water to reach the panels.
NOTE: If cleaning your panels from the ground is not possible, do not attempt to access your rooftop unless you have the appropriate safety equipment and training. If you don’t; hire a suitably qualified professional instead.
Clean your solar panels on an overcast day, early in the morning or in the evening. If the sun is beating down on the panels, any water used can quickly evaporate and dirt will become smeared.
Early morning can be a particularly good time for cleaning as dew that has settled on the panels overnight will likely have softened grime; meaning you’ll need to use less water and less energy to clean your solar panels.
If the panels are dry, before tackling the modules with water, brush off any loose materials first – this will make cleaning easier and faster.
Don’t use metal objects or harsh abrasive products for removing caked on materials – scratching the glass on a solar panel can affect its performance as scratches will cast shadows. Avoid using detergents if possible as these may streak the glass of the panel. Use of abrasive powders also risks scratching the panels.
Given the nature of good quality solar panel glass, clean water and a little scrubbing with a coarse cloth covered sponge or soft brush should remove the most stubborn grime. Plastic scourers may also be used.
If your mains-supplied water is hard (mineral-rich) and rainwater is available; use that as a final rinse; then squeegee dry. If hard water is all you have, just be sure to squeegee well as mineral-ladened water can form deposits on glass as it dries.
Dealing with oily stains
Oily stains can occur in some installation scenarios, such as if you live near an airport and are under a flight path or if you live adjacent to and downwind of a major roadway frequented by trucks. If oily stains start appearing on your panels; isopropyl alcohol can be used as a spot-cleaning substance..
The final word on solar panel cleaning
The old saying “if it ain’t broke, don’t fix it” applies – in most residential installation scenarios, solar panel cleaning just isn’t worth the bother – or the potential danger if accessing your rooftop. Unless dirt is clearly visible or performance is noticeably impacted; simply let nature do the job for you – just as it does in creating solar power :).