When the insulation resistance of the photovoltaic field is less than 1M0, the inverter indicates an insulation fault. Then there is a disconnection from the public grid.
Measure the + / Earth, – / Earth and +/- voltage to identify the grounding of a positive or negative pole of the PV. Check that the power of consumers does not exceed 3kW without the presence of the public grid. Please contact your installer to check and correct the ground fault of the electrical installation to stop disconnection.