How do you balance two battery setups ?

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Darkwing

New member
Joined
Feb 10, 2021
Messages
29
Hi

I have hit a snag in my system.

I have a Growatt SPH 3600 hybrid inverter, and a victron Multiplus II 48/5000 diy kit (with color gx). They are each their own phase. the Growatt has 6000kw solar attached.
I have two further solar systems
a SMA setup running at approx 6000kw
and a series of 250 panels with microinverters theoretical 6000kw, in real life they suck and are about 1500kw.

I had hoped that i could just set two smartmeters (Growatt runs rs485) and Victron runs a EM24 TCP up in the very front of the electric board.
Both monitor all three phases. I was hoping that they would kind of just balance, but in the end the Growatt discharged into the Victron system. I tihnk some sort of ramp up occurs. So the smallest difference in measurements, will cause one to start the ball rolling, and steadily increase effort to deliver consumed electricity.

I dont think i can change much on the config on the Growatt, so im down to the Victron, and splitting the system into phases. This sucks because i would then have to decide what supports what and have one phase i cant cover.
A physical work around is to isolate one system and its consumption to an early place one one phase, send remainder of the phase to the one covering all three phases

An alternative angel of attack is the build a man in the middle for the victron, so i intercept the EM24, modulate its values to half. In theory i would have to do the same for the Growatt rs485. This will take time and i'm not sure i will be able to complete the task. By doing this i can send a percentage of the messaured values to the device.

Im currently leaning towards rearranging the physical flow (phases), but it requires an electrician to spend considerable amounts of time rerouting my cabling. (law requirement).

Does anyone know if i can make like a deadzone in the victron, like you can with game simulation wheels ?
Or can you recommend some sort of clever fix... i'm all ears.

One recommendation to everyone else.... buy one big system, don't do like me, i bought used equipment below wanted scale. Not the smartest i have ever done.
 

Extremetaz

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Aug 16, 2021
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6
Need to understand this a little better:

You have a 3ph connection.
Growatt hybrid, with storage, in parallel on P1
Victron hybrid, with storage, in series on on P2
SMA of some description on P3

...with the microinverters distributed across the three?
 

400bird

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Apr 27, 2020
Messages
97
Also, 250 panels and 6,000-1,500kw?
So 1,500,000 watts from 250 panels?

That would be 6,000 watt panels on the low end
 

Extremetaz

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Aug 16, 2021
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I think he means 6kW using 250W panels on individual microinverters. (ie: 24 panels & inverters)
 

slimf

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Sep 26, 2017
Messages
169
Ditch the growwatt and do it properly.
I have a MPII 5000va on L1.
I have an EM24 measuring my grid.
And a 45kwh battery.

you need to plan the system better rather than hack bits together. Your not playing in toy territory with that gear.

what are your two batteries?
 

Extremetaz

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Aug 16, 2021
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Easy now gents - he's clearly got some idea what he's at, and there's certainly no harm in using what's available to you to try and get the job done.

If the system is as I've outlined above, then the only real issue is, as he suggests, that the Growatt and the Victron units can't talk to each other.
If this was three different parallel connected Solar inverters with no storage then it would all be fine - it's account for the storage that's the trick.

The easiest solution I see here, again as he suggests and slimf above confirms, would indeed be to either delete the Growatt, or forget about putting storage on it and just let it run in solar only mode. AFAIK that unit only uses the battery when the grid connection is absent anyway, it doesn't do power sharing (happy to be corrected).

That however brings us back to the situation where the main distribution board needs rewiring to permit the Victron (now with all the battery storage on it) to manage the secured loads on its phase - and whilst I know this will be a pain, it will also be a lot easier than trying to develop a MITM solution to permit the Victron to slave the Growatt unit.

Final option then is to add another Victron, and ideally with 2 of them to give you a proper 3ph solution. You can still use the parallel inverters on the AC-in side of the Victrons if you're that way inclined, so you don't have to ditch them; but I wouldn't use uncontrolled inverters of comparable power on the AC-out side as that has the potential to seriously mess with the Victron control.
 

400bird

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Apr 27, 2020
Messages
97
I think he means 6kW using 250W panels on individual microinverters. (ie: 24 panels & inverters)
I figured his labeling was wrong, I just wasn't going to do the math for him. OP can clarify his system and answer everyone's questions.
 

Darkwing

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Feb 10, 2021
Messages
29
Hi

More specifically:
SMA Sunny Tripower 6000TL-20 running 28x250. It is a three phase device
Growatt sph3600 is running 14x450w, it is a single phase, not sure if it is on p1,2 or 3. 2x batteries Growatt GBLI6532 Lets call it P1
Victron multiplus-ii 48/5000, BMW i3 60 ah battery repacked to 48v. running on different phase than growatt. lets call it P2
Furher 24x250 panels with individual microinverters, running on same phase as Victron., These only provide as if they were like 24-125.

Currently im down to two options im wondering. Isolating the victron and microinverters and "one phase" of the SMA, then put the EM24 i use for that. There by making it a closed set. The result of the closed set would then run to the main board, where i can put the SMD630 to control the growatt, to collect any remainder positive or negative flow.
Alternatively is to make a man in the middle device to programmatically control the number they see. Ie only let them see 50% of the actual number. This has drawbacks: if one battery goes low, the other can always only fix half of consumption/overload... and since they are not nearly the same, this will happen. By doing MITM this i dont have to call the electrican back. But if i decide to move stuff, i need to pay the electrician to do so.
Maybe my mistake was to run both of them on multiphase meters. But if both are single phase i cannot cover one phase, and i still risk offset usage between the remaining two phases.

Yes if i was smart i bought one giant setup. However its no so easy, local law only allows devices on a danish whitelist. So that narrows the field somewhat. All of it has been paid for with unexpected earnings, and is therefore somewhat "drip" oriented.
 

slimf

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Joined
Sep 26, 2017
Messages
169
If I understand correctly, you have a 6.5kwh battery on the growwatt and only a 2.8kwh on the Multiplus (way undersize for the inverter)

maybe sell the Victron gear and expand the grow-watt solution.
 

Darkwing

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Feb 10, 2021
Messages
29
Actually growatt is 2 x 6.5 and 8x2.8 (i think its 2.8, its i3 60ah complete pack)) on the victron.
Currently trying to organise coding of a modbus value splitter. Not the easiest task in the world.
Also looking at going back to previous sub optimal setup, where i have a bunch of gear and minor amount of solar behind EM24/Victron, and have the SMD630 at the meter talking to the Growatt.This setup is known to be good, but will give me very limited value for the victron/i3 battery. Problem is to channel enough solar power to that point, i can currently only channel the less good 24x250(125) behind it. this is well below what would make sence. To make sense the SMA would need to be behind it too, that would generate enough surplus power to allow that there is something to collect.
Pretty sad at the moment, but i will find a way. Currently im force charging the i3 battery out of pure spite :) and at least i know that there is a partial solution that has worked for me before..
 
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