MultiPlus II en PowerAssist / PowerWall

DIY
, , ,
1

A few questions about the MultiPlus II in use as PowerWall with use of PowerAssist please.

Preparing for the Dutch 2027 loss of “salderen” I am considering the option of a powerwall.
Meaning I would like a system that monitors the current at the entry point of the utility meter and try to keep it close to zero.

  • Monitor at utility meter seems covered, as the MultiPlusII has the external sensor for that.
  • Keep entry current low: for that we have PowerAssist, and if I check the demo-library, I can set it as low as 1 Amp. Close enough.

Am I correct in my understanding of the MultiPlusII? Even if I take 3x3KVA in a 3-phase setup?

Additionally, what I am wondering about is the charging. In spring/summer, about 9 months of the year, solar will keep the batteries full. But alas, with my heatpump, those months are also the least energy critical.

During Winter is when the real cost would happen. I’d love for a battery big enough to store all summer energy but that is not going to happen.

However, I would like to use the MultiPlusII charger capability with dynamic pricing, to basically charge batteries during low-prices, and keep my heat-pump active 24/7

Can the MulktiPlus somehow do this. Possibly by programming some external RasPi or even ESP32 to retrieve prices and control MultiPlusII charging over modbus or something.

Possibly I have the needed programming skills, but I would still need to know that MultiPlusII is “open” in this sense. Or maybe someone already build this. Or better yet, it is already in the device’s functionality.

Thanks for your responses.

Edit: just discovered the ESS page and D-ESS page. Still, additional remarks are welcome.

2

Yes ess is the way to go, also add a grid meter connected to the system, with ess you can keep a slightly negative grid setpoint so you will always use pv and or battery also at night

I do this too and about 9-10 months a year i hardly use grid power (3x multiplus 2 3k and 20kw pylontech, whole house connected to ac out)

With dess you can also use dynamic grid prices

I suggest to contact a local official victron dealer for system design, with a heat pump i think you should go for 5k or larger multiplusses

3

The heatpump is also a 3 phase model, meaning relatively low load per phase. So I am thinking 3x3KVA might be enough. Also depends a bit on the price difference, oversizing is good, when not too expensive.

You mention pylontech, but I only see high voltage batteries. I thought MultiPlus only goes to 48V?

So the DESS fully automatically talks the right protocols to pick the pricing info from the net?

4

The mp 3000 is 2400w continue so take that in account, the 5k is also not that more expensive

Pylontech US5000 (or 2000/3000) series is 48v and fully compatible

Yes thats watt dess does, i have no experience with dess only ess