Many components comprise the solar system. Such components include the solar panels, inverters, mounting hardware, monitoring devices, the electrical wiring and devices, storage batteries. They are reliable components with no moving parts, no user-serviceable parts, and require no user maintenance.
The only potential maintenance in solar systems is solar panel cleaning. Over time, and depending on your environment, the panels may become coated or covered with dirt and debris. There may also be events that coat the panels with soot from fires, sap from nearby trees, or bird droppings. In most parts of the country, normal rainfall will keep the solar panel clean. If you are aware of such events occurring or notice a constant drop in production for no obvious reason (e.g., cloudy weather), then the panels should be visually checked and cleaned.