A day with lower production does not necessarily mean there is a fault. Cloud cover, shorter days, high panel temperatures, dirt, and seasonal shading affect performance.
Compare days with similar conditions and longer time periods, also using the estimate from the system design. Check whether the app is updating normally and whether it displays an alert. In a system with export limitation or a full battery, lower power may be due to the operating mode rather than a fault.
Contact the installer if there is a persistent, unexplained drop, a recurring error, or zero production during hours when normal operation is expected. Send the dates, error code, and screenshots of the charts, without handling the equipment.
Do not climb onto the roof or open electrical panels to inspect them. If you notice a burning smell, smoke, or visible damage, move away and seek appropriate assistance immediately. Do not attempt repeated restarts without guidance.