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david-laferney avatar image
david-laferney asked

Is big PV voltage drop at MPPT controller normal?

Open circuit voltage and current are normal when measured at the controller with the wires disconnected, but when connected to the controller the voltage across the wires drops very low. Is it normal?

Searching shows many variations of this question, but no definitive answers that I've seen. It IS suggested that a bad wiring connection could be the cause - I've seen this answer accepted, but not confirmed. Can it also indicate a problem with the charge controller? If it could be either one is there some way to tell which without just going through and redoing all of the connections - and if that doesn't work assume it's the controler?

Or does experience indicate that it is almost certainly a wiring issue? In my case, the controller seems normal but doesn't turn on to charge.

MPPT Controllerswiring
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

Give us some numbers. What is the Voc? What voltage is "drops very low"?

Maybe some screenshots.

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david-laferney avatar image david-laferney Matthias Lange - DE ♦ commented ·

img-2815.png68v 7 amps from 6-100w Renogy mono panels - 3 in series 2 of those in parallel. Dropped to almost nothing. Why is the charger off? = "insufficient PV power"


I am indeed working on an issue...

https://community.victronenergy.com/questions/132987/mppt-10050-actually-getting-pv-power-but-charger-o.html

but the question is - when your PV array is making power (lets just say 67v 7amps) if you check the voltage across the PV connections on the controller do you get a reading close to 67/7 or less than 12v?

I'm trying to determine if I have a wiring issue or a charger issue. Since I just went through and replaced all of the wiring connections - I'm getting more positive that it's probably the charge controller.

90% there.


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1 Answer
snoobler avatar image
snoobler answered ·

So you're already engaged with the community on this issue, but you need to start a new thread on the same issue?


This is very poor etiquette and ultimately wastes the time of the people trying to help you.


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david-laferney avatar image david-laferney commented ·

I sincerely apologize if I violated the norms - I am new here though. I did however read the rules for posting, one of which was:

"One Question per post

This community is intended to become a knowledge base. We want people to be able to quickly search for their question, and find the answer."

What I intended to do was ask a separate question that admittedly does relate to the issue I'm trying to work out - not intentionally reasking the same question. I don't quite understand what I did wrong.

But thanks for being so helpful.

May I assume this means you don't know the answer?

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