Goodwe or Inverex single source problem?

I just came to know today that the inverex inverter doesn't work with a single source option. Is this true or not?

Is this the case with Goodwe as well?

For ppl who don't have the background, single source means if there is no battery and utility electricity goes away, then the inverter won't pass through the solar power. Ideally it should. Can someone Veteran shed some light on it or not?