The PV inverter screen shows that the PV voltage is too high or the insulation resistance is too low

 Fault analysis of high PV voltage displayed on the screen: DC voltage is too high alarm

Possible cause: Too many components are connected in series, causing the voltage to exceed the voltage of the inverter.

Solution: Due to the temperature characteristics of the components, the lower the temperature, the higher the voltage. The input voltage range of the single-phase string inverter is 100-500V, and the recommended voltage after stringing is between 350-400V. The input voltage range of the three-phase string inverter is 250-800V, and the recommended voltage after stringing is between 600-650V. In this voltage range, the inverter has high efficiency and can generate electricity when the irradiance is low in the morning and evening, but the voltage will not exceed the upper limit of the inverter voltage, causing an alarm and shutdown.

Fault analysis of low PV insulation impedance displayed on the screen: The ground insulation resistance of the photovoltaic system is less than 2 megohms

Possible cause: There is a short circuit to the ground or the insulation layer is damaged in the solar panels, junction boxes, DC cables, inverters, AC cables, wiring terminals, etc. The PV wiring terminals and AC wiring casings are loose, causing water ingress.

Solution: Disconnect the power grid and inverter, check the resistance of each component's wire to ground in turn, find out the problem point, and replace it.