question

salvun avatar image
salvun asked

MultiPlus 2 3PHase system to grow over time

Hello everyone, I hope this question has not already been asked to many times.


I want to quickly state that I do have a lot of electrical experience. As I am a trained electrician by trade. So this is not coming from the mind of a untrained individual.


So I own my own machine shop since a few years. As I made a career change and started my own business. The thing that bugs me is that we use a lot of power. Well over 20MW per year and I have been really looking into running my workshop here as much as possible of solar and off grid as I can. Since we have plenty of roof space still available and land to put solar on (Already have 20Kw Solar installed. This is the legal grid connected maximum if you want to avoid tons of red tape.)
There are a lot of legal limitations to grid tied solar setups, and the coming "Peak usage" charges are really pushing me into doing this.

My current setup:

3Phase +N 63Amp grid connection (Meter 1)

  • 7,5Kw 3Phase screw compressor
  • 25Kw max. 3Phase CNC Mill #1 (Usually 5kw or less. But 22Kw motor with Ramp-up draw)
  • 25Kw max. 3Phase CNC Mill #2 (Usually 5kw or less. But 22Kw motor with Ramp-up draw)
  • 5Kw max. 3Phase CNC Mill#3
  • AC units to climate control the shop.

    3Phase +N 32Amp grid connection (Meter 2)
  • House (Basic usage)
  • Office (Lighting mostly)
  • Servers (1.2Kw Servers)
  • Warehouse (Lighting and forklift charger)


Both meters are on the same property and the ultimate goal is to have the entire property on a Victron system with battery's charged as much as possible from solar. With a grid "Trickle" charge as a backup.

Since this entire plan would require a very expensive system to get going. Making me lean to build into this slowly and buying units section by section.
My idea to start was to order 3 Multiplus 2 5000VA setup in 3phase to get started with a couple of 4.8kwH battery packs. Allowing me to setup a smaller system to learn and gain experience by slowly moving loads onto this starter system.
This would be setup in a dedicated technical room with AC housing all the battery's and solar controllers.

Then as things grow, add more Multiplus 2 units. From what I read it would need to be all 5000VA units to grow the system by a set of 3 units at a time. With a goal of having 4 sets in total (12 inverters total.)

Any expansion would always be done in sets of 3 units to keep the entire system symmetrical at all times.


The main question now, does this seem workable. Especially with the time in between adding more Multiplus units. Or is it WAY more recommended to just jump into financial pit and get 3 15000VA units of the bat.

I do like the idea of having more individual units a lot more, since the system can be grown with better up front cost distribution and it looks more robust since if a single 5000VA unit fails, it will not take down the entire microgrid compared to having a single big unit per phase


The reason I want to ask this here and not to a local reseller, is to avoid financial bias from the reseller to try and just push a more expensive option.

Thank you so much for reading and providing some feedback if possible.
-Pieter

Multiplus-IImultiplus in parallelmicrogrid
4 comments
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2 Answers
nickdb avatar image
nickdb answered ·

The challenge with systems like this is rarely the wiring. It is understanding the tech, configuration, customisation etc.

For a complex system like this you really want to do the free training and read every config guide imaginable.

If not, you’re likely to expect one thing and experience another. This forum is really not for design work, especially of complex systems.

There are many unhappy posts from people who had expertise but not the experience of working on systems like this. Doing the research will avoid this.

The devil is in the detail, and there is a lot of detail.

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nickdb avatar image
nickdb answered ·

I am going to be a spoilsport and close off this topic.

We really don't encourage complex system design, as per t's and c's of the community.

I would suggest you engage a qualified Victron tech, or speak to a distie/supplier in your region for official help.

https://www.victronenergy.com/where-to-buy

Sales managers contact info in your region is also available on the main site.

Alternatively, to DIY, sign up for free at professional.victronenergy.com and follow the online certification.

Read wiring unlimited, the ESS design manual, the parallel and 3 phase system setup guide and the Cerbo manual for some good background.

Specific queries, if not already available via search on the forum, can easily be answered here.

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