sunny boy inverter ,varistors ?

[Bankjobbob]

Just come back from a site where the sunny boy 2000hf is not generating there is dc coming in and the 240 is good but it looks as though it's not
Registering the dc ,could this be the varistors? The site is 100 mile round trip so will take some with me if it's a possibility. Anything else I should be looking for ?
Many thanks bob

[Mike90250]

I doubt the varistors are in a DC circuit. or that they are replaceable. There is a 5 minute qualification period where the inverter tests the grid for stability and only then (if it passes the FQ, Voltage and Impedance testing) will it start up and backfeed the grid.
Any glitches on the grid would prevent the inverter from starting up.