Hoping I can get some guidance before I go to investigate possible issues.
On my RV I have to separate arrays. The front panels are 3X190w in series to a 100/50 mppt controller. The rear is the same except it’s 4x200w in series to a 100/50 mppt controller.
Today the rear panels produced exactly zero watts despite showing an input of 95v with zero amps.
The first thing I will do is reboot the mppt controller. Then I guess I will head to the roof to check all the connections. Some initial reading says most common issue is a bad connection somewhere. I don’t understand how it can still show volts with a bad connection.
Just looking for the simplest places to look before I start taking things apart.
Then I agree that you should check all the connections. You can still see voltage over a high resistance connection but you won’t see much, if any, current flow. Just wait until see your first Class-T fuse pass voltage but no current and you scratch your head for a while until you replace the fuse and everything works. Blew my mind the first time
You state it was showing 95V, that is very close to the 100V limit of your mppt and the limit is a hard limit. If the voltage exceeds 100V then the mppt can be damaged. Cooler temperature can increase voltage. Consider swapping from 4 in series to 2 series x 2 parallel as long as you are charging 12V or 24V.
Normally it’s well below the limit. But thank you . You brought my attention to the higher than normal voltage. Interestingly that voltage is the combined VOC. Meaning I definitely have an open circuit. Now to go find out where.
The other reason for getting Voc on the input to the mppt is you have lost connection to your batteries so the output voltage rises to absorption or float but there is no or very little current going to your batteries, so the controller stops taking power from the panels. Check your mppt to battery wiring, fuses or breakers. Do you have cheap no brand thermal breakers like those below, these often stop working for no reason.
Thank you everyone. Problem solved and I learned a valuable lesson!!!
The wire coming from my MPPT 100/50 to the battery bank goes to a DC breaker. That breaker was rated far too high (200 amps). The line from the breaker to the battery is approx 5’. It was 10 guage wire. Leftover from the solar panel run. It had ferrules on it. It’s been operating for over a year.
However, my usage of the solar has been minimal. Really only trickling to the battery. During a recent heat wave, I have been relying heavily on the solar often times send 30 or 40 amps to the battery from that controller.
The recipe for disaster was perfect. An undersized wire should be 6 guage. An oversized breaker should be 20v 50amp max. A loose connection in the MPPT side.
The result was fortunate. A melted wire, a blown and melted breaker. This could have easily been a self imposed disaster.
Suffice it to say, I scared myself. I’m revisiting all my cables, using correct wire guage, and ensuring I meet the required specs. Thank you to all who commented and hope others can learn from my near catastrophic error.
