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mrcleanx asked

Low panel voltage on MPPT 75|10

This just started this season. Solar voltage fluctuates between 0.5v and 6v every .5 second when the 100w panel is in direct sunlight. Wires at the MPPT terminals read 18v+ coming from the panel, so none of the cable connections appear to be the problem. I'm using a BMV-712 as well, which has been monitoring just fine. Anything else I can test, or is it a busted unit? Thanks!

MPPT SmartSolarSolar Panelvoltage
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5 Answers
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klim8skeptic answered ·

@MrCleanX Test your solar panel to see if the panel is faulty.

If the panel passes the test, repeat the test at the mppt pv terminals, to check array to mppt wiring.

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mrcleanx answered ·

That is where I'm checking the panel voltage, at the bare wires that screw into the 75|10 terminals.

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klim8skeptic avatar image klim8skeptic ♦ commented ·
@MrCleanX Did you watch the video I linked?
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mrcleanx avatar image
mrcleanx answered ·

OK....finally got some sun today! Not perfect sun, but enough. Panel is putting out ~18.5v and ~5.5 amps. I don't think it's the panel.

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seb71 avatar image seb71 commented ·

18.5V is not that great.


What's the Voc from the panel specifications?

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info-6 answered ·

How many Volts does your battery have?

As far as I know, the panel voltage must be at least 5V higher that the battery voltage, to make the MPPT work stable.

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seb71 avatar image seb71 commented ·
That's correct, but still the MPPT should report the 18.5V for PV voltage, not 0.5V - 6V.
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seb71 answered ·

When the PV panel is connected to the MPPT and the MPPT reports PV voltage of 0.5V - 6V, if you measure at MPPT PV terminals with a multimeter, what values you have?

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