I have a 35 kWh battery storage system and currently run a Victron MultiPlus-II 48/5000/70-50 on a single phase. In autumn, winter and spring, its charging capacity is sometimes insufficient to fully charge the battery during the available periods of surplus PV generation.
I have three MultiPlus units in total, which I could also run in a three-phase configuration. However, I don’t need the additional discharge capacity. I only want to be able to charge faster when there’s a sufficient surplus. I’d like to avoid the additional self-consumption during continuous operation: assuming 60 W for the two other units, that would amount to around 526 kWh per year.
So far, I’ve used an additional MultiPlus as a charger only and switched it on when there’s a PV surplus via a Shelly.
Can this also be done using Victron’s built-in features? The aim would be to activate the additional MultiPlus for charging only when there’s sufficient PV surplus, and then switch it off again in the most energy-efficient way possible.
What configuration and, if necessary, additional hardware would be required? Is anyone using a solution like this?
I once tried this for a customer with NodeRed, but couldn’t find a solution I was happy with. With rapidly changing cloud cover, you don’t want it constantly switching back and forth, and after being switched on, the Multi also needs a little time to synchronise with the grid, switch on and start charging.
But I’m probably just missing the right idea.
There’s also an AC-Thor in the system, which handles the surplus; that could have played a part too.
that is possible. however, you’ll need a separate GX for each MP2 to control it. you can get the smart meter data from the master via node-red, along with all the other data you need!
without node-red, you’ll also need a separate smart meter for each system!
you can easily prevent it from constantly switching on and off by using the total PV output to control it. For example, switch on at 4 kW and off at 1 kW, and also use a lockout period: only switch off if the PV output stays below the minimum for 30 minutes.
So, I can transfer energy in both directions between the 48 V and 36 V systems using the combination of an MP2 3000 ESS and an MP2 5000. It works really well.
Nope, the additional Multi can simply be connected to the GX device via an MK3 interface.
That way, you can control it just like the “main Multi”.
Unfortunately, we’re not talking about that much power here, so you can’t use such a wide hysteresis.
And you don’t want to end up drawing power from the grid unnecessarily or feeding too much back into it because of timers that are too long.
The whole point is to charge the battery as quickly as possible during the few hours of sunshine in spring, autumn and winter, and if you use a 30-minute timer, too much power goes back into the grid.
Given enough time and/or know-how, you could certainly come up with a good solution yourself, but I can’t really charge the customer for several hours of work.
I also assume that @Lala isn’t a programmer who can just knock something together, otherwise they wouldn’t have asked the question here.
with just one GX, you’re quite limited in terms of charge control. It’s then only possible via the input current limit, or you have to rely on the current BMS data also being forwarded to the additional Multi. I’ve never tested that.
I only need the energy transfer at the beginning and end of winter. However, I can also transfer energy via a DC connection using isolated DC-DC converters, but they haven’t been fully integrated yet, as the control system is still missing.