question

A three way transfer switch would allow you to connect a generator to the AC-input of the Multigrid / Multiplus-II while safely isolating the grid. This would require a licensed electrician.

However this configuration is not recommended, as the programming of ESS seeks to minimise import from the AC-input, when running a generator you wish to minimise generator run time. There is also the possibility of back feeding to the generator, which is never recommended.

Depending on your backup requirements, perhaps the safest way would be to put the three way transfer switch between the Multi and the loads. This way once the battery in the ESS system is exhausted, the multi is disconnected safely, and the generator runs the loads until the grid / solar supply returns. Not optimal for generator run time.

Perhaps others users have some better design options?

One other note, I would HIGHLY recommend a Victron MPPT DC solar supply of some sort, so that your system can automatically wake up if you discharge your batteries to the point when the multi shuts down (and with it your AC solar).

Hi Guy,

thanks for your answer.

My main question was: what happens if I supply the Multigrid with a generator instead of mains supply. Will that work at all or is a generator output too unstable so that the Multigrid shuts off?

An additional problem: when generator frequency is not absolutely stable the AC-coupled PV-inverters will switch off.

I agree, DC coupled chargers would be much better (not only for the issue that the system cannot start with empty battery), but the AC-coupled invertes are already there.

Regards,

Martin