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obediah-mcmajor avatar image
obediah-mcmajor asked

Connecting 2 MPPT 100/50 to battery bank and CCGX

Hello everyone. I need help, and it’s urgent, please...

We are doing an upgrade to our solar system. We currently have a PV array of 6 x 320w, 36.8v, 8.69A panels, 6 CEIL 200/AH deep cycle batteries, for a 24v output. We use a Victron 100/50 MPPT charge controller and 2 MultiPlus 12/3000/70-50 - 230V inverters/chargers - paralleled. There is a Victron battery balancer and a Victron BMV-702 connected to the battery bank too. We have a Victron CCGX for remote operation as well. We need help with the following:

1. Is it necessary to connect 2 MPPT charge controllers in parallel? What purpose would they serve?

2. If that is the case, should we combine the charge controller wires before they reach the battery bank, with a bus bar or Victron MEGA fuse?

3. Or connect them directly to the battery bank and independently?

4. How do we connect them to the CCGX? Should we connect one or both? There is only 2 VE.Direct ports on the CCGX, to which 1 MPPT and the BMV-702 are connected right now. I’m in a fix.

Our electrician suggested 2 MPPT charge controllers for back-up (which I thought would just be for redundancy) but I thought I would enquire from the Victron Community. Please help ASAP...and thanks!


MPPT ControllersCCGX Color Control
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2 Answers
JohnC avatar image
JohnC answered ·

Ok, all good. 24V it is.

So you have 1920W of panels. Your existing 100/50 mppt could handle about 1400W of that at full tilt. Then clip the top from the solar bellcurve. Which may not be an issue depending on what you're doing, but you have solar capacity enough for about 70A of mppt charge.

Your 6x batts in 2S3P configuration would be 600Ah @ 24V, and that'd be a good match for 70A.

Let's say allocate 4x of your panels (1280W) into your existing /50, and 2x into a new 100/20 (close enough). Paralleled in, wired as you choose, but neat & tidy & logical is always good.

That's what I'd do. And the adaptor for the usb port..


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obediah-mcmajor avatar image obediah-mcmajor commented ·

That’s great. I have a better understanding of my options now. Thank you!

By the way, how did you come up with 70A?

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JohnC avatar image JohnC ♦ obediah-mcmajor commented ·

It's generally considered/recommended that pb batts charge up to 10% - 20% A of their Ah rating. For you, 10% is 60A, but a little more won't hurt. If you're running concurrent loads then that might be useful.

You could also look at your VRM graphs to see if the mppt is flatlining at 50A, and for how long. No point expanding charge capacity if you don't need it.

'Overclocking' your existing mppt is fine too (within technical limits), and those 6x panels will help with poor weather and lengthening your solar day.


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obediah-mcmajor avatar image obediah-mcmajor JohnC ♦ commented ·

Wonderful! You’re a star. Thanks again. I really appreciate your help. Now I can work on my upgrade...

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JohnC avatar image
JohnC answered ·

Hi @Obediah McMajor

Sorry, but maybe more questions than answers..

You say '24V output' batts, yet 12V Multis. One each from halfway along the bank?? Not surprised you need a balancer..

It's really hard to answer anything without clarifying this.

Your single 100/50 mppt is good for ~700W into 12V, or double that at 24V. Wire more capacity parallel. (subject to my first question)

Q4/. Extra VE.Direct ports via usb, with a https://www.victronenergy.com/accessories/ve-direct-to-usb-interface

We need more info..

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terryj avatar image terryj commented ·

So how many Charge Controllers can the GX support? 3?


Many thanks,

Terry

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JohnC avatar image JohnC ♦ terryj commented ·

The CCGX is listed as 5. But there's other models too. See also 'Note 1' in this link: https://www.victronenergy.com/live/venus-os:start


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