Hi I set up 4 375w panel in series and installed the cables on the first mc4 switches. All working fine. Then I put a second series same panel but only on in series on the second mc4 connector. The 250/100 stopped working...showing only 0-6 watts. Did I destroy it because of 2 different strings? thanks
Sounds like you have reverse polarity connected the second string.
I agree with @klim8skeptic on this. Your first set of panels is fine, and should be about 120-160v and about 10a or so. I don’t understand exactly what your second string consists of... one panel? You say in series, so I’m not sure. Your connection to the second MC4 set puts that string in parallel to the first string, but should still be ok if it’s just 1 or 2 panels. Check your wiring on both ends. Sounds like something is reversed somewhere.
I have 2 string with 4 panels each in series. Polarity is fine. I checked it several times. (see attached pictures) And when I plug in the cabels from the former working string nothing happens.
@skykay For the sake of clarity. Did you connect the first string to the controller using the first set of MC4 and then added the second string to the second PAIR of MC4 connectors? All I can think is the panels were energized at the time and you should not connect live wires as this could well have damaged the controller or blown the internal fuse. Otherwise check the fuse between the battery and the charge controller, assuming you have one. Fuses featured a lot in recent posts.
Ok, I am sending it back to have it repaired...thanks
