Multiplus II 48/3000/35-50 in North America grid connected system

DIY
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1

Thinking of this configuration for use in North America that would allow use of a pair of Multiplus II 48/3000/35-50 120v in a grid connected building to provide split phase 240v. Modest domestic needs would be supplied by Multiplus II inverters with high amperage intermittent loads pulled directly from the public grid. During winter batteries would be charged as needed from the public grid.

2026 Config - Ecoworthy charger - Picture only
2026 Config - Ecoworthy charger - Picture only786×735 108 KB

Clearly there would be no ESS and I would lose some efficiency charging batteries from grid AC. Battery charge/no charge could be handled by the programmable Eco-Worthy 100Ah 48v charger.

Is there a better solution that would keep me out of UL1741SB hot water with my local electric company?

2

I don’t know about this acronym. Could you explain what problems it is presenting please.

3

It is a US standard for connecting inverter systems to the grid.

4

I found out that much from a search engine. But the results didn’t tell me the issues the OP is trying to overcome.

5

Quick question: Which electric company? Those MultiPlus II have UL1741 edition 2 certification, which is a little bit below UL1741SB. Since you’re not pushing power back to the grid, does the electric company still require SB ?

6

Yes, many if not most service providers prefer (or require) devices that interact with their grids to have the SB certification.

7

Only if you are interacting with the grid. But, as you said, that’s not necessary in your case. I’ll make a few professional recommendations you are free to ignore. Just know I’m trying to help, not be a PITA.

  • Buy a better battery that has a quality BMS inside, is supported by Victron, and will give you reliable SoC readings without the use of an external shunt. Here in N.A. I would recommend Pytes V5 or V16 batteries.
  • The Lynx Shunt is just as inaccurate as the current shunts built in to cheap BMS’s. Steer clear of the Lynx Shunt
  • The MultiPlus has a built in charger. Why would you want to use an external charger?
  • I would suggest you work with a local Victron dealer who can help you with some of these design choices
8

Local Victron dealer only does remote cabins, boats and RVs. A hard “No” to anything grid connected.

9

Being connected to the grid is not the same as grid-interactive. In your case, it’s just a battery charger. Maybe they are paranoid about permitting. Call us or someone closer to you. We love working with DIYers. Since you are only supplying critical loads, you probably don’t even need a permit. But if you do, it’s easy for you to get for yourself and we can help with that. I’m not here to sell my company, but if we can help let me know.

10

I appreciate your generous offer. Thanks.

11

It wasn’t generous. I was just suggesting an option. :slight_smile: I’d still prefer people work with someone local-ish when possible. Have fun.