Connector too hot

Please see a photo attached. I have ten 100-watt panels and 6 batteries in my system. I am using three P30L charge controllers and the damaged connector is the one that connects to four 100-watt panels. Any idea why it got so hot? ntrollers

 

How were the panels wired?
Series or parallel?

 

most over heating problems are ether bad connection or too small for amount of current .

 

Batteries are in parellal connection.

 

That is what I was thinking too.
With so many panels in parallel.
With a pwm controller I would connect 2 in parallel.
Then jump a wire size to the next set.
Then again at the next set.
I did one better here.
http://forums.windynation.com/community/threads/flying-as-of-6-30-2010.197/page-5

 

I made a combiner box.
Had 3 sets of two panels.
I hooked all of them to a 6 gauge wire.