On-Grid Systems if installed correctly poses little maintenance related challenges, rather than washing your PV panels periodically, but as human errors/Environmental factors are always there so here are few tips.
If you have a small spot (3×3 inch) on one of your solar panels such as dirt, dust or bird dropping it significantly effects unit production, as panels are wired in series. Make sure panels are cleaned periodically and thoroughly.
Always watch out of shades such as new building or over grown bushes and trees, shadow means less generation.
Lose connection or a faulty MC-4 connector or a DC breaker will affect your generation.
Leakage in any DC string wire (common problem) will cause your system to shut down, so check for any cuts and bruises on the DC cables.
If your inverter has no ample ventilation, it will shut down due to overheating.
If your panel is hit by a bullet , immediately get it by passes by the contractor and replace it when desired.