The system itself
Is it worth paying to have solar panels cleaned?
The short answer
Check the production data first. Where soiling is uniform dust and it rains regularly, the recoverable gain is usually small. Where it is concentrated — bird droppings, lichen, pollen, agricultural or industrial deposition, or a low-pitch array that never sheds — it is worth it, because a shaded cell drags on more than its own area.
How to decide with data rather than a sales call
- Compare this season's production with the same season in previous years. If it has not declined, cleaning recovers nothing.
- Look at the array from the ground. Patchy deposits matter more than an even film.
- Consider the pitch. A shallow array sheds far less than a steep one and soils faster.
- Consider what is nearby: trees, birds, a main road, farmland, industry, the coast.
If you do buy it
- Ask what they clean with. High pressure and harsh chemicals damage coatings and seals.
- Ask whether they have height safety equipment and insurance for roof work.
- Ask for photographs of the array and a note of anything found: cracked panels, lifted flashing, corroded isolators, damaged cabling.
- Consider bird proofing at the same time if birds are nesting under the array, which is common and causes real damage.
Do not do it yourself on a roof. A wet, sloped panel surface is one of the worst walking surfaces on a building.
Also asked
Does rain clean solar panels?
It removes a good deal of uniform dust, which is why cleaning often recovers less than expected. It does not remove bird droppings, lichen or sticky deposits, which are exactly the kinds of soiling that cost the most output.
General information about solar and about hiring, not advice about your roof or your tax affairs. Incentives, net metering and contractor licensing are set federally, by state, and by your utility, and all of them change. The authority that publishes the rule is the current answer.