Growatt SPF5000ES schematic

[radurus]

Hello

I have one SPF5000ES which does not power on if only grid is connected.
I mean it does not power on without battery.
All functions works properly. (It was replaced in warranty by a new one)
I dismantled it in pieces to clean it up from the dust (~20 months of running).
I want to find the issue (why does not power on just with grid) and fix it. I suspect it is a problem with the internal power source block on the mainboard.

Anybody having a schematic or point me to the component which is defect? (I know this is a defect others encountered)

 

[Samsonite801]

Is it designed (supported) to operate in batteryless mode?

Does it have settings in the menus for service priority like many inverters do? Like for example USB, SBU, SUB modes?

U = Utility
S = Solar
B = Battery