question

David Gould avatar image
David Gould asked

Series Inverters

I have a customer system on a farm I am doing some work on. Is it possible to feed input 1 or 2 of a Quattro with output from a inverter? The system ideally would be the Victron Quattro 15kva with 10kwh lithium storage at one and of the farm then 400 meters away there is a 12v battery bank of about 30kwh with lots of panels and a MPPT 250/100 Victron solar charge controller.

Ideally I would like total an inverter off this system and feed the output of the inverter into the Quattro setting the current limit of the Quattro to match the inverter.

Any thoughts / suggestions would be appreciated and perhaps does anyone know if the out put of a Quattro or Phoenix inverter can be fed to the input of another Quattro


Thanks


MultiPlus Quattro Inverter Charger
2 |3000

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5 Answers
JohnC avatar image
JohnC answered ·

Hi @David Gould

I believe that's possible, and that there's people out there actually doing it. But it's not a supported application, so you'll be hard-pressed finding anything about it in the literature. The remote supply would need to be treated as an independent source of ac, like a generator might.

Just curious.. 30kWh is a lot of batt at 12V, and a 250/100 would be almost like a trickle charger into that much. And if you depleted them could take days to recover..


2 comments
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David Gould avatar image David Gould commented ·

@JohnC thanks for that, slight typo in my brief, there are actually I think 6, maybe 8 of the 250/100's and something in the region of 80 panels

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JohnC avatar image JohnC ♦ David Gould commented ·
Wow. I feel a nightmare coming on when i go to bed tonight.. :)
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Phil Gavin avatar image
Phil Gavin answered ·

Andy, from the off-grid garage, frequents this forum I believe:

https://www.youtube.com/watch?v=SsTkgoN6ENM

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David Gould avatar image
David Gould answered ·

@Phil Gavin thanks for the video link, just what I wanted to do but couldn't see in the books if you could.

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shaneyake avatar image
shaneyake answered ·

Series inverters are not supported by Victron. Let's make that clear.

However you can definitely build a system with series inverters. I have a system that is running like that with multiple inverters behind a master inverter all in different buildings. It is possible and the system I am running has been working flawlessly for the last 2 years. However this is not a simple task and there is a lot involved to make it work correctly.

It is specifically tricky to get the slave units to export to master but does all work.

What country are you in?

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David Gould avatar image David Gould commented ·
I am in the uk, the system has an victron anti islanding device in it.
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shaneyake avatar image shaneyake David Gould commented ·

I have a blog post on how my system works. Feel free to comment on the blog if you have any questions.
https://shaneyake.blogspot.com/2021/09/micro-grid.html

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ben-stanton avatar image ben-stanton shaneyake commented ·
That blog post is really good! Would you be keen on sharing your Node-RED logic?
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shaneyake avatar image shaneyake ben-stanton commented ·

It is custom depending on the setup. I am planning to do another blog post which explains the control side in greater detail. I am happy to work on these projects, so if you need help implementing NodeRed control just use the contact form on my blog and we can setup a zoom call.
https://shaneyake.blogspot.com/

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ben-stanton avatar image
ben-stanton answered ·

I now have three systems running with series inverters and none of them using Node RED (yet!).


1: My first one: Selectronic master with 24V Lead Carbon and 3kW AC-coupled Fronius and some DC via Victron MPPTs. Downstream is a Victron Easysolar II 48/3000 with a Freedom Won 5/4 Lithium battery. Series running a tiny house. The control is pretty simple but works. Basically set the master to frequency shift (yes, Selectronic can be set to do this) then set the slave up as an ESS system. The Country code then needs to tick "Enable DRM0 functionality" and you can play with the Frequency settings but start with "Fstop is 52 Hz." Then under ESS allow exporting from DC and I have set the grid target to continually export 300 watts so that if there is very little load in the tiny house the Lithium battery just exports to support the main system. When the downstream battery is depleted it simply then "imports" energy from the master system as a normal load would.


2: 3 Phase, grid connected Quattros as master with 5 x 15/12 Freedom Wons and downstream is 3 phase Multiplus II with some old BYD (which couldn't be expanded due to being obsoleted) - smatterings of AC and DC coupling in various locations around the site. Similar DRM0 setup and the system operated as per expectations when on and off grid.


3: Single phase, off grid - customer wanted to use old 24V lead and ADD 48V lithium - easy with series systems.

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