diy solar

diy solar

Multiple MPPT Solar Charge Controllers to the same battery bank

A

ArranP

New Member
Joined
Nov 5, 2020
Messages
71
I am aware that multiple Victron MPPT solar charge controlleres can be connected ( in parallel ) to the same battery bank.

I approached a budget manufacturer POWMr and asked them if multiples of their MPPT charge controllers can be connected to the same battery bank and they replied "Parallel connection is not possible because the battery readings of the two machines will affect each other"

I have just been unlucky and got a misinformed tech/sales individual ?
 
diysolarforum.com

Charging from multiple sources

One can have as many independent charging sources running concurrently as they like provided they are programmed properly for the voltage of one's battery bank. Examples (some or all at once, even multiples of a single type, different brands, etc.): Solar PV via MPPT Solar PV via PWM AC-DC...
diysolarforum.com diysolarforum.com

True that the chargers will influence each other's voltage readings, because you can't apply a charge current without producing a voltage rise. This in no way precludes use though.

Speaking of Victron, if you can feed the MPPTs with a direct voltage measure, you eliminate this issue. A smartshunt in a VE.Smart network with one or more MPPT feeds the open circuit voltage and current (and temperature if smartshunt equipped with a sensor) to the MPPT thus eliminating the charger-measured voltage value that's influenced by current and wiring resistance.

Allegedly, some EPEVER models can be connected to coordinate charging among multiple MPPTs.
 
Last edited:
Rednecktek said:
Worst case scenario the 2 controllers read slightly different voltages from the same battery and one of them goes into "stop charging, battery full" mode when the other one tops off the last little bit.
Click to expand...

Yep, and the effect is minimal. I have been running parallel MPPT controllers (of different brands) on the same battery pack for many months without issues.
 
Victron SCC's CAN be in parallel as they can link & communicate with each other & use the Smartshunt to control the affair. Midnite Solar Classic SCC's (and the new Hawk Bay & Barcelona's too) can be linked in parallel as well (they use the WizBangJr Smartshunt for managing). Now these are not Value Grade cheapsters !

It CAN be sone with cheapo stuff as well BUT you have to do the hard math & hard thinking to make it work just right. That means really making sure that all voltages, losses & the biases are accounted for. Yes there is a BIAS issue which few ever mention... an SCC will read voltage differently whether it is charging or not. Some have offset settings to help account for that while many SCC's do not and you have to correct the settings manually, even for as little as 0.5 volts difference... believe it or not a 1/2 Volt difference with Lithium Based batteries can cause weird issues. Fact is, that wire, connections (lugs etc) all increase losses and resistance and that must be accounted for.
 
Steve_S said:
It CAN be sone with cheapo stuff as well BUT you have to do the hard math & hard thinking to make it work just right.
Click to expand...

Like what? Just set them for the same voltage and walk away. No hard math or hard thinking required. As noted above, mine are working just fine. Am I "maybe" loosing a watt or two? Maybe, but not enough to even give a second thought to.
 
Texas-Mark said:
Like what? Just set them for the same voltage and walk away. No hard math or hard thinking required. As noted above, mine are working just fine. Am I "maybe" loosing a watt or two? Maybe, but not enough to even give a second thought to.
Click to expand...
I agree, just hook it to the DC bus and let it do it's thing.

Steve usually you post some good stuff but in this case I don't see the reasoning. I don't use any communication between SCC's. If I do add more PV down the road, I will use some of the MPPT's in the LV6548's I'm not using now. It will work just fine.
 
Whatever amount of SCC's you have 2 or 4 or 6 etc.,.. They ALL need to see the battery bank voltage exactly the same, their settings need to match up as well, lest one be doing bulk while another is floating etc... All wire, lugs etc add resistance & voltage loss, not a lot per piece but it is cumulative across the entire "string" as it were. IF you are using identical SCC's that's easier to setup but if you geta mix of them, that's when interesting things start to popup... talk abouit chasing wild cats...

I use Midnite Classics, Paralleled using network cables between them and interconnected via the E-Panel with the WizBangJr Smart Shunt. Even adding in a Midnite Kidd Controller into the mix (standalone) caused some quirks & foibles. BUT never mind my experiences... what do I know.
 
Steve_S said:
Whatever amount of SCC's you have 2 or 4 or 6 etc.,.. They ALL need to see the battery bank voltage exactly the same, their settings need to match up as well, lest one be doing bulk while another is floating etc..
Click to expand...

Even IF one sees a different voltage (only really matters or at near full charge), the other one will pick up the slack. Really a non-issue.

And once you are at the float threshold, current has dropped significantly meaning the minor resistance differences (if any) will also be negligible.
 
Last edited:
Steve_S said:
Whatever amount of SCC's you have 2 or 4 or 6 etc.,.. They ALL need to see the battery bank voltage exactly the same, their settings need to match up as well, lest one be doing bulk while another is floating etc...
Click to expand...

It really doesn't matter. I run a pair of SCC's to a positive and negative busbar, then a larger cable to a Victron 1000A busbar. The Victron is where the 4/0 cables from batteries go to and each inverter has 2/0 running to it from that busbar. The setup is shown in one of my videos.

At close to 100% SOC, one SCC might be inputting 300W and another 600W. It doesn't matter, it would be the same as when panels on one array are shaded and potential power to the SCC is limited, while another array that isn't shaded can supply full power to another SCC for that array. Both will feed the DC bus depending on what loads are on the SCC's, doesn't matter if that power is going to inverters or the battery bank.

I also see this as no different than multiple MPPT's in an AIO with some strings shaded and some not. Power is put on the DC bus according to load on that bus.
Steve_S said:
All wire, lugs etc add resistance & voltage loss, not a lot per piece but it is cumulative across the entire "string" as it were. IF you are using identical SCC's that's easier to setup but if you geta mix of them, that's when interesting things start to popup... talk abouit chasing wild cats...
Click to expand...

I have yet to see a single problem and I've been running the pair of EG4's since late July. Many days of 4.5Kw input from 4.24Kw of panels per SCC.

Once constant voltage charging is hit both SCC's cut back on output.

Steve_S said:
I use Midnite Classics, Paralleled using network cables between them and interconnected via the E-Panel with the WizBangJr Smart Shunt. Even adding in a Midnite Kidd Controller into the mix (standalone) caused some quirks & foibles. BUT never mind my experiences... what do I know.
Click to expand...
Quite possibly if you are using some type of communication hub to link battery BMS's to SCC's, then you might experience what you are seeing. I don't use any comms, I don't think it is necessary.
 
Yes it is no problem. I use 5 MPPTs on the same battery bank. One of them is a powmr, (rebranded iPanda explorer series).

As someone mentioned set all the charge settings the same. Even if one mppt is off by .1v, you can compensate for that in the settings or leave it and it will only come into play as they reach the very top of charge.
 
Texas-Mark said:
Yep, and the effect is minimal. I have been running parallel MPPT controllers (of different brands) on the same battery pack for many months without issues.
Click to expand...
I am looking at two MPPT 100/48 charge controllers (EG4 MPPT500vdc100A)... not sure if it will work to keep the Absolyte GX 48v/2,000A battery fully charged. Still studying and trying to learn best method(s) to accomplish our being off grid.
 
NevadAdobe said:
I am looking at two MPPT 100/48 charge controllers (EG4 MPPT500vdc100A)... not sure if it will work to keep the Absolyte GX 48v/2,000A battery fully charged. Still studying and trying to learn best method(s) to accomplish our being off grid.
Click to expand...
What do you want to know about them? I run a pair of them. I have an older video out there showing settings and how I wired them in. You can find it on Youtube.

These will only have communication with EG4 batteries. I don't need communication for them, I just run USER settings. These will also not report the PV harvested each day and won't export any data to Solar Assistant.

There is a firmware update for these, the units I had would occasionally set a code under low light conditions. The firmware addressed that code and the 2 units have worked flawlessly since then. I installed one in July last year and the other in first week of August.
 
Zwy said:
What do you want to know about them? I run a pair of them. I have an older video out there showing settings and how I wired them in. You can find it on Youtube.

These will only have communication with EG4 batteries. I don't need communication for them, I just run USER settings. These will also not report the PV harvested each day and won't export any data to Solar Assistant.

There is a firmware update for these, the units I had would occasionally set a code under low light conditions. The firmware addressed that code and the 2 units have worked flawlessly since then. I installed one in July last year and the other in first week of August.
Click to expand...
Thanks, Doc - I appreciate all the direction in the past week and a half in regard to the charge controller. Been online and on the phone with Schneider, Midnite Solar and Signature Solar. I think that your charge controllers seem to fit the bill for our needs but I will have to rewire the Conext SW4048 which has the Classic 150 prewired (I think)...still working on it for sizing solar arrays/strings. The snow hasn't helped in the past week either - can't get up the mountain to the sea container...lol. Blessings and Good Cheer!
 
NevadAdobe said:
Thanks, Doc - I appreciate all the direction in the past week and a half in regard to the charge controller. Been online and on the phone with Schneider, Midnite Solar and Signature Solar. I think that your charge controllers seem to fit the bill for our needs but I will have to rewire the Conext SW4048 which has the Classic 150 prewired (I think)...still working on it for sizing solar arrays/strings. The snow hasn't helped in the past week either - can't get up the mountain to the sea container...lol. Blessings and Good Cheer!
Click to expand...
If you want to track your PV production directly, you can always use a Victron Smartshunt after the charge controllers set as an energy meter. I've thought of adding one. I can track production in other ways, the shunt would allow knowing production and also some time limited data storage.

I've been quite impressed with the EG4 units. I saw again yesterday both MPPT's were pulling 4.5Kw at peak sun from 4.2Kw of panels. I do recommend slightly underpaneling the EG4 MPPT's, this allows pulling full rating from panels.
 
You must log in or register to reply here.

Similar threads

nycamper62
Question on running dual mppt controllers on the same battery bank
Replies
1
Views
273
400bird
4
U
Parallel Charge Controllers Limiting Each Other
Replies
12
Views
598
Tomthumb62
Tomthumb62
M
Does MPPT charge controller damages a battery ?
2
Replies
36
Views
1K
Q-Dog
Q-Dog
prkrgrp
2 separate Arrays connected to 2 separate charge controllers to one bank in parallel?
Replies
16
Views
741
timselectric
T
D
Batteries won't charge on small solar system
Replies
9
Views
312
AmpD
A
Back
Top