Dual "SmartSolar Charger MPPT 100/50" setup - one of them keeps turning off

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jeff-lawrence asked Mar 13, '22

Dual "SmartSolar Charger MPPT 100/50" setup - one of them keeps turning off

I have (2) SmartSolar Charger MPPT 100/50 devices connected to 2 different solar arrays in a 24v configuration with my Lifepo4 batteries. All has been great until the last couple weeks where I have notice that one of the MPPT's does not work all the time. I have checked the wiring and actually swapped the solar array's between the controllers and one of always goes into "Off" State. If i completely reset the system from the batteries or the array, both MPPT's will come back online and charge for about a minute and then one will go to the "Off" state. it is always the same MPPT. I dont think anything has changed in the last few weeks. I did update all the firmware during the troubleshooting,but that did not help. I found something similar in the link below but it was related to firmware. what can i do to figure this out ???

both MPPT's are running v1.59

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https://community.victronenergy.com/questions/17760/help-pls-help-bluesolar-mppt-v139-firmware-file.html

MPPT Controllers

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Answer 1 · 2022-03-13T20:59:28Z

klim8skeptic answered · Mar 13, 2022 at 08:59 PM

Your pv voltage is to low for the mppt to reliably start charging.

Please explain how your arrays are wired up.

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Answer 2 · 2022-03-13T21:02:54Z

wkirby answered · Mar 13, 2022 at 09:02 PM

When you see that MPPT goes to Off State, in the app it should also offer a reason why the charger is off:

If you touch on "Why is the charger off?" then it should show you one of the reasons:

Then maybe you can get closer to the problem.

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jeff-lawrence commented · Mar 13, 2022 at 09:38 PM

i checked the voltage from the array to the MPPT and it is above 35v. however, when I check the voltage at the input for the PV on the MPPT (with the array wires connected) it goes to around 26v. When I remove the input wires from the MPPT and check the pos/neg wires it is the same voltage as the array, above 35v.

I do understand the voltage needs to be greater than my batteries.

The issue is that one MPPT is not working correctly.

again, i know both the solar arrays work because I have connected them both to the working MPPT as part of my troubleshooting. (individually to make sure each array was working)

both MPPT's have the exact same settings and firmware and battery is set to LiFePO4.

I have removed both MPPT ve.direct cables to try standalone and again, only one MPPT works correctly and the problematic one goes to the "Off" state

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Answer 3 · 2022-03-13T22:04:44Z

jeff-lawrence answered · Mar 13, 2022 at 10:04 PM

I narrowed it down a bit more.

I have 2 MPPT's (Array A) and (Array B)

When both are connected to everything, (Array A) goes to "Off" State, while (Array B) stays online.

If I disconnect (Array B) from PV power and reset the whole system, (Array A) is fine and happy and stays online and charges the batteries. The PV terminals on (Array A) are over 30v.

As soon as I turn the PV power back on for (Array B), the PV terminals on (Array A) go to same voltage as my battery, around 25-26v and then it goes to the "Off" state and (Array B) does all the work.

I have tested all of this with and withOUT the ve.direct cables connected. no change in results

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Answer 4 · 2022-03-13T22:25:26Z

jeff-lawrence answered · Mar 13, 2022 at 10:25 PM

so i think i got it solved. I set up the 2 MPPT's on their own "VE.SmartNetwork" - they seem to be playing nice. I read something about firmware 1.47 and later using "synchronized charging"

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Answer 5 · 2022-03-13T23:32:13Z

jeff-lawrence answered · Mar 13, 2022 at 11:32 PM

Nevermind...

They worked great together for about an hour and then (Array A) went to "Off" State.

not sure what else to do....

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Answer 6 · 2022-03-14T00:03:25Z

klim8skeptic answered · Mar 14, 2022 at 12:03 AM

the PV terminals on (Array A) go to same voltage as my battery, around 25-26v and then it goes to the "Off" state

You have a high resistance joint between the mppt and panels.

Your pv voltage is still to low, can the array be wired in 2 series strings?

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jeff-lawrence commented · Mar 14, 2022 at 03:30 AM

as noted in my previous post(s), there is no issue with either solar array. there is no issue between the MPPT and the panels of either PV array. It is an issue with the MPPT's working together. Each MPPT works fine by itself, no matter what solar array it is connected to.

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Answer 7 · 2022-03-14T06:05:43Z

JohnC answered · Mar 14, 2022 at 06:05 AM

Hi @Jeff Lawrence

What's happening here is that Array A is too low in V. When Array B is producing it will raise Vbat too closely to the Vmp of A (within 1V), so A will shut down.

Either the panels are different in each array, or there's a panel fault in A.

The strung V's aren't ideal anyway, and if you could string in series this wouldn't happen. Maybe that's not possible due to panel numbers.

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jeff-lawrence commented · Mar 14, 2022 at 02:01 PM

I understand and completely understand what you are saying. However these 2 MPPTs and solar arrays have worked great for the past year. The voltage at the array and before the MPPT input terminals are nearly identical, like the day I installed them. The MPPts just stopped working together.

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