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100/50 MPPT Incorrectly Indicating 0V PV input (SOLVED)

I have 2 x 160W Renogy panels connected in parallel feeding into a 100/50 Smartsolar MPPT. Testing the PV leads with a multimeter shows a 21.2 voltage, yet when the leads are connected to the MPPT all I get is a blinking blue "Bulk" light flashing once each 3 seconds. The bluetooth app indicates 0V across the solar leads, while measuring the voltage across the connected terminals with the multimeter yields something like 0.3V. I have double checked that the polarity of the PV inputs is correct as labeled, though it is possible that the installer mislabeled.


The MPPT is meant to charge 3 x 100Ah battleborn lithium batteries. Battery voltage measured with both multimeter and a connected BMV-712 has been in the range of 13.12V. Charge parameters have been set to 14.4V bulk/absorption and 13.6V float. The charging algorithm has been left at "battery life" since I have no information about what these algorithms entail.


Anyone have any ideas on what might be wrong here? I've read that there may be a bad crimp or MC4 connector, so that as soon as the MPPT tries to draw current things fall apart. Does this seem to make sense?


Any help would be greatly appreciated. I've been struggling with repairing this install job without much success!

MPPT ControllersMPPT SmartSolarmppt charging
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2 Answers
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klim8skeptic answered ·

"it is possible that the installer mislabeled. "

Yeah, I would check that with your multimeter.

Another possibility is that the pair of panels have been wired cross polarity.

Or perhaps the fuse is blown/breaker is open.

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dvant answered ·

Problem solved. The outfit who installed the electrical system mislabeled the negative and positive from the PV array. Reversing the connections led to normal operation. The drop in voltage at the terminal was likely a reverse polarity protection function. While I am surprised that there is no warning through the app or light notifications to indicate reverse polarity, I am impressed that the MPPT 100/50 has withstood that exposure without any apparent damage.


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