question

joerge avatar image
joerge asked

MultiPlus or MultiPlus-II as well as further recommendations

Need some installation advice.

Have a 11kWp PV on my roof (in Germany) with a "SMA STP 12000TL-10" PV-Inverter.

Now, that the grid power costs differs that large to my buy-back earnings, I would like to add a battery.

After a lot searching, I recognized the impressive open sources and community of Victron Energy, and I just got a Raspberry Pi 3 B+ running with VenusOS as well as I got my Tasmota connected SmartMeter successfully connected to VenusOS.

Now I think it's time to get the missing parts, and for this I like to get some advise from you:

  1. Which Inverter/Charger shall I use?
    I'm currently undecided between "MultiPlus 48/2000" or "Multiplus-II 48/3000".
    From the point of power, the "Multiplus 48/2000" would be sufficient, but I'm unsure if it will play well with the VenusOS and how it will work with the ESS.
    Or if there's another argue why to use the Multiplus-II?
  2. BTW: Where does the ESS get handled? On the VenusOS right?
  3. Anything else I should consider to order beside the MK3-USB, Battery and the AC+DC cabling?

BTW: I plan to start with a 4.8kWh LiFePO4 Battery, but like to be open to add a second battery, or either switch to a 2nd Multiplus+Battery in parallel ... or either up to 3-phase.

Multiplus-IIVenus OSRaspberry Pibatterygrid
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2 Answers
kevgermany avatar image
kevgermany answered ·

No real difference between the models in terms of Venus. The II models are quieter and should have lower standby power/higher efficiency.

Be careful about three phase. The multipluses need to be closely matched. Best to get all together or upgrade quickly after checking compatibility with your dealer

Batteries. Check compatibility. Some don't work well. The better ones integrate with others from the same maker and balance each other as well as talking to Venus. This can be expensive to fix if you get it wrong.

ESS is Venus, yes. All pi questions should be posted in the modifications space.

Depending on the BMS, you may or may not need a smart shunt.

Lynx Distributor will tidy the installation and make a second battery easy to install.

Consider system voltage. 48V probably best.

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Delta Victor avatar image Delta Victor commented ·

Best to check if both are accepted by local grid rules. As far as i know only the multiplus II has the certified double anti-islanding relays.

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dirk-s avatar image dirk-s Delta Victor commented ·

Right, for this use Multiplus II is the right choice.

I would not recommend 3 phase for future. It costs to much, have to much efficiency losses and not needed if you don‘t plan to make your full home off grid for emergency.

Better only to put some emergency users/equipment to the AC Out1 for emergency off grid reasons. That will be the most cost effective and smart solution.

With a Multiplus II 3000 you can also add more battery in future if you want.

If you don’t want to build you battery by yourself I would recommend Pylontech US3000C or US5000. This is a reliable solution and works out of the box. It’s used by many users.

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kevgermany avatar image kevgermany ♦♦ dirk-s commented ·
Pylontech worked out of the box for me. But follow the Victron guide.
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joerge avatar image
joerge answered ·

Thanks a lot for all of your quick and detailed answers, as well as recommendations!

There have been a couple of argues I wasn't aware before. I.e. the certificates ;-), as well as the 3-phase argue, Lynx Distributor, ...

So looks like I should go with a "Multiplus-II 48V" and check once more my consumption graphs if I better choose directly a 5000VA instead of a 3000VA, for the benefit of skipping my dual-multiplus or 3-phase extension thoughts.


Regarding the batteries:
I've already seen the Pylontech's and I like them in special because they would perfectly fit into my 19'' Server-Rack without much work, but I also have thrown an eye on the cheap "Power Queen 25.6V 100Ah LiFePO4's", putting two in series. I didn't checked Victrons compatibility list in detail yet, but I mean to remember that they wrote somewhere that in principle every LiFePO4 should be compatible.

However, I'll check it before, but I ask myself if there's any argue against putting two in series. In my understanding not, because also a 25,6V one is a collection of lower voltage cells in series.

BTW: Wish you all a happy new year!

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