The general rule: minimal maintenance
On a classic sloping roof, the panels are largely cleaned with rain. Losses related to dirt often remain modest and do not justify frequent maintenance.
Avoid risky interventions
Climbing onto the roof without equipment is dangerous and can damage the modules. When in doubt, It is better to initiate a professional check rather than an improvised intervention.
Decide with production data
The good indicator is the abnormal production gap (in comparable weather conditions). If the drop is clear and durable, targeted cleaning or inspection is warranted. Otherwise, too frequent maintenance generally does not bring economic gain.