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maxhogg avatar image
maxhogg asked

MPPT 75/15 showing 0V and 0A despite 24V input from PV panels

I have measured the PV voltage at the input terminals, and it is 24V as expected.

I have tried reversing polarity as suggested, but it made no difference.

I have tried contacting my dealer, but have had no response.

Is there anything more I can try, or could the unit be faulty?

Thanks,

Max


MPPT Controllers
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klim8skeptic avatar image klim8skeptic ♦ commented ·
Measure the short circuit current of the PV array.


No current (baring blown fuse in multimeter) equals a bad mppt to PV connection.


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maxhogg avatar image maxhogg klim8skeptic ♦ commented ·

Thanks - tried this and no current suggesting the problem is with the PV arrray/connections I guess. I'm surprised that a voltage is detected though. To be honest, we are reaching the limits of our knowledge (both of us are more mechanics than electricians) so may need to seek more expert help to solve the PV connection issues, if that is indeed the issue.


Thanks very much for your help.

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kevgermany avatar image
kevgermany answered ·

Is this a new installation?

Please post a screen shot of the MPPT settings.

Who suggested reversing polarity? This could damage the unit.

What batteries are you charging?

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maxhogg avatar image maxhogg commented ·

Thanks for the reply.


Not new - installed and functioning well for ~2 years previously.


Screenshot of battery settings:

screenshot-20211227-215022.png


Sorry - to be clear we reversed polarity on the solar panels, not the battery. Pg 42 of the manual suggested that this might be a possible issue.


We are charging a Yuasa 100Ah leisure battery in a campervan. The battery is also charged via the alternator and a 12v charger, both of which are functioning well.


Thanks so much for your help.


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screenshot-20211227-215022.png (177.6 KiB)
ejrossouw avatar image
ejrossouw answered ·

In what sequence did you hook up the mppt? Also, is it set up for the correct battery voltage? Did you check the fuse? Finally, inspect the terminal block connectors and see whether their soldered connections to the PCboard are all intact.

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maxhogg avatar image maxhogg commented ·
MPPT was already hooked up - the installation was previously functioning well. In trying to find the fault we did disconnect the MPPT, and when reconnecting hooked up the battery and then the PV array as suggested in the manual.


Battery voltage set to 12v.

We haven't checked the fuse because the connection from the MPPT to the battery seems fine (judging by the app correctly displaying the battery voltage). I'll try that now.

On your final suggestion - I'm nervous of opening up the MPPT! Would this invalidate the warranty?


Many thanks for your help - much appreciated.


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ejrossouw avatar image ejrossouw maxhogg commented ·
The device cannot be opened or serviced. I'll send a picture a bit later of the area to inspect.
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ejrossouw avatar image ejrossouw maxhogg commented ·

Hopefully not this bad as it is not covered by warranty, but worth a look. Did you try a reset back to factory defaults as well as ensure the latest firmware is applied? I personally don't believe it will make a difference, but everything is worth a shot.

1640710428627.png

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maxhogg avatar image maxhogg ejrossouw commented ·
This is so helpful, thanks. No, all soldered connections are intact. Supplier has now called and agrees it is likely a fault with the MPPT, so has asked that I return it for testing/replacement. Thanks so much for your help, though, much appreciated.
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kevgermany avatar image
kevgermany answered ·

If you have 24V the right way round on the input side of the MPPT, then not likely to be wiring to the panels. But measure this on the MPPT screws.

What voltage do you measure on the output side of the MPPT? With an without the panels.

If there's a battery monitor, please post the values it sees from the MPPT. In other words make sure the other charging is off.

What voltage do you see at the battery?



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maxhogg avatar image maxhogg commented ·

As above - thanks so much for your help. The supplier has now called and is taking the MPPT back for testing/replacement. I really appreciate the guidance and replies.

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