I have expanded my system to 21 kWp and therefore installed a new Verto Fronius inverter with a Fronius Reserva battery, 15 kWp. At the same time, I would like to continue operating my old MultiPlus2 3000 with a 10 kW battery. It is connected in such a way that excess electricity not required by the house is directed into the battery instead of being fed back into the grid. The MultiPlus therefore serves only as an inverter for the household circuit.
So far, everything is working — but how can I prevent the Fronius battery from charging the Victron battery, or vice versa? And how do I configure the MultiPlus so that it only starts supplying power once the Fronius battery is virtually empty? The Victron is only intended as a backup, i.e. a secondary battery.
No, the old system ran brilliantly for 10 years, then 5 years ago it was supplemented with a MultiPlus and a battery in the home system. The inverter has now failed, so I expanded the system at the same time with a new inverter, twice the PV capacity and a DC-coupled battery. But I don’t want to simply shut down the Victron.
That’s just to clarify things; unfortunately, your answer doesn’t help me. Thanks.
As I’ve already written, a system like this is unfortunately always a bit of a mess.
It would have been better to expand the Victron system accordingly instead of using a separate battery for the Fronius.
In other words, replace the faulty PV inverter like-for-like, expand the battery in the Victron system, add one or two more MultiPlus units, and connect the PV expansion to the battery via MPPTs.
How exactly is the system set up now?
You should be able to influence its behaviour to some extent by adjusting the position of the grid sensors and/or the grid setpoint.
Otherwise, you’ll have to intervene manually using external control or NodeRed to achieve the desired behaviour.
The MultiPlus and the battery are installed in the AC circuit, just before the electricity leaves the house and is fed into the grid. The battery is therefore only charged when I am not using the PV electricity in the house—there are no solar panels connected to it.
I have also programmed this battery with Node-RED so that at night, from 11 p.m. to 6 a.m., it feeds a maximum of 1 kW/h into the grid (because I sell the electricity to my neighbours through a virtual community energy scheme).
The Fronius battery, on the other hand, is charged directly by the PV system. I have programmed it to feed 2 kW back into the grid for the neighbours during peak periods, from 7 to 9 p.m. and from 6 to 8 a.m.
Using Node-RED, I can also prevent the Victron battery from charging in the morning between 6 and 8.
We are still 100% self-sufficient despite this.
I would now like the Victron battery to respond more slowly—in other words, not to supply or charge immediately, but for the Fronius battery to always be active first. How can I do that? Thanks