question

Robert Deans avatar image
Robert Deans asked

Voltage drop at Mppt 100/50

I have just fitted 3 x 175w Victron panels in series to my 100/50 controller.

The input voltage to the mppt is jumping about all over the place. The cables from the panels are all connected properly and when not connected to the mppt it sits steady at 67v but as soon as connected to the controller the best is 63v but drops down as far as 24v sometimes. Because of this I don't think the yield is very good. I crimped ferules on cable before refitting but doesn't make any difference. Is this normal? Ive never had the open voltage jump about so much before

MPPT Controllersvoltage drop
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6 Answers
nickdb avatar image
nickdb answered ·

Ferrules are not to be used with Victron MPPTs.

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Robert Deans avatar image Robert Deans commented ·

I only fitted the ferules to see if they might help. They are not the issue

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Duivert NL avatar image
Duivert NL answered ·

Maybe measure the voltage of each panel first, just to see if they deliver a stable voltage?

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onrbikes avatar image
onrbikes answered ·

Is there a circuit breaker or switch between panels and mppt?

The cable from panels isn't kinked along the way

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Alexandra avatar image
Alexandra answered ·

Are you sure the jumping up and down is not tracking?

By series you have clipped them with their own MC4 connections together? Check that they are home the whole way. Sometimes the click sound is not a good indicator.

Bad connection is definitely the place to start with troubleshooting.

You will probably will have to test each individually if that is not the case. Panels might be damaged.

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kevgermany avatar image kevgermany ♦♦ commented ·
@Robert Deans

Could also be an internal fault in one of the cables.

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Robert Deans avatar image Robert Deans commented ·

I have checked everything staring from first panel. At the ends of the cable that you connect straight into the mppt I have a steady 67v never waivering. As soon as I plug it into the mppt it loses 5v and jumps about. I also ran 2 new cables pulled off a drum of 50m and ran it direct to the mppt to eliminate any issues with breaker or kinked cable. The only thing I don't have and haven't changed because I don't have one is the mppt itself.

Ive fitted lots of panels in the past and never had this problem before.

It can be viewed on vrm

https://vrm.victronenergy.com/installation/272788/share/3db11d19

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Robert Deans avatar image
Robert Deans answered ·

How do I make it visible? It's on my vrm and its in the device list


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klim8skeptic avatar image klim8skeptic ♦ commented ·
@Robert Deans Advanced > top RH corner (widgets) > device + > select parameters to display.
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kevgermany avatar image
kevgermany answered ·

I've just taken a look at your link, worked for me..

  1. MPPT shows in VRM as PV, bottom right.
  2. It looks ok, stable, but low output, probably low light. On my systems, solar output can be as low as 5% of panel rating or less in winter. Yours is about 80W at the moment.
  3. Initial voltage drop/changing is to be expected. This is the MPPT putting a load on the panels and then optimising to maximise output. This can take a couple of minutes. The MPPT will repeat this every 10 minutes to track the light changes. But you're going to see it will be shorter, less variation.


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Robert Deans avatar image Robert Deans commented ·
thanks for the reply I will monitor it for a few weeks. thanks everyone for your help
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