I try to understand how the Multiplus II can keep the energy meter of the grid to zero in a parallel ESS topology. The “ESS design and installation manual” shows the following figure of that configuration :
In this figure, the only way for the Multiplus to feed the (non-essential) AC loads is by supplying AC through its input relais. However, this seems to me quite unlikely. But how does it work then ?
All help is welcome. I am considering to build my own ESS system, with Victron products (which I have been using with much satisfaction on my boat for quite a while).
Thank you, Marc.
As I am used to the off-grid system on my boat, wherein the input relais opens when no shore power is detected, I found it peculiar to see that power could be sent back in a grid-tied ESS system.
But do I understand it correctly that the Cerbo (or another GX device) “commands” the Multiplus (based on the signal from the energy meter) to feed power back through its input in order to compensate the AC loads ?
If you are allowed to sell PV energy, you have to send it back via ACin into the grid.
In case you have a bigger AC coupled PV, it makes sense to put a part on ACin for normal grid tied operation and a part on ACout to obey factor 1 rule.
The PV inverter on ACin will shut down on grid failure.
But in normal operation it will source you EV, house load and even charge your battery via the MP2.
Also in case you retrofit an existing AC PV, you can put the MP2 parallel as AC coupled battery to improve self usage of PV energy or even have an uninterupted power supply for some loads.
