How to restart rooftop solar on camper?

[Thylacine]

I have a simple solar setup in my campervan. 200W of solar on the roof, leading through an mppt controller to a 100Ah lithium battery. I’ve been using it for four years now without a hiccup.

However, a few days ago after a week of cloudy days, everything went blank. The MT50 display was gone, as was the BMV-712 screen. The sun came out and it made no difference.

I then hooked up a 120W portable panel using a simple controller, and the screens started coming to life over a couple of days. I got the battery up to 100% charge. When I disconnect the portable solar panel, the rooftop solar simply does not register. Any ideas on how to get it going again?

 

[chrisski]

Trace the wires from the panels to where they connect in the trailer. Look for breaks.check the wiring for Loose connections in the SCC and corroded solar cables. Also could be a fuse blown.

With a DMM, trace back the connections for voltage. Good volts into the SCC could mean the SCC went bad. Also, check the SCC out for voltage, and so forth back to the battery.

 

[Texas-Mark]

Check your panel voltage at the controller. Sounds like a bad connection somewhere.

 

[Rednecktek]

Sounds like it's either a loose connection or a dead MPPT. Have you poked the solar wires with a meter to see voltage?

Does the MT50 show no solar coming in? You can try a reset where you disconnect the solar, disconnect the battery, then reconnect the battery and solar (in that order) and see if it sees the solar again.

If you get good voltage at the panel wires but the MPPT says nothing there, it could be a fuse inside but more likely the MPPT has given up the ghost.

 

[Thylacine]

Thanks, everyone for your help. Bad weather has kept me indoors but yesterday I went poking around and finally found the culprit -- it was a break in one of the connections from the solar panels, right where it passed through some plywood holding the charger.