I'm planning an installation for a small workshop in a location where grid power is limited (230V/10A). There will be a constant load (heat pump) plus peak loads for a short period of time (say up to 6kW nominal power for a minute or so, when power tools are being used). I would like to supplement the available grid power with batteries for those peak loads.
I found the MultiPlus (48/5000/70-100) and it seems that its PowerAssist feature is exactly what I need. So far so good.
But — I could also add a small amount of solar to the mix. And that's where I don't understand things anymore.
Ideally, I'd like this ordering of power sources:
1. Use as much solar as is available at the moment.
2. Use the AC grid connection to pull up to 10A.
3. Use the batteries for anything on top of that.
But it seems that the MultiPlus does not have a separate DC connection for a solar power source. I found a system example (https://www.victronenergy.com/upload/documents/MultiPlus-system-example-5KW-24V-230V-AC.pdf) which is fairly close to what I want, but it seems that the output of the MPPT controller is connected directly to the batteries. It seems to me that in this system, if I configure the PowerAssist feature, the solar source can only supplement battery charging and supplement the power peaks over the 10A I can pull from the grid, but it can't participate in small loads if the batteries are fully charged?
I would like to avoid discharging the batteries as much as possible, to extend their lifetime. They should be used only for supplementing peak power above what grid+solar can supply at the moment.
Additionally, I do not understand this example: I thought batteries need to be charged according to a charging profile, and it seems like there are two chargers connected to the same batteries. How does one ensure proper charging?
I think what I was expecting was an inverter/charger with separate connections for battery and for DC in (from solar/wind), with source prioritization.
Can this kind of prioritization be done with the MultiPlus?