MC4 connectors male and female pair for solar panel - eBay
I saw these and really liked the heavy duty solder-type pins..
Those flimsy thin crimp-on pins just didn't look robust enough..
http://www.sunstore.co.uk/csi/926679...leexploded.jpg
I got 2 male&female pairs, and the quality looks good.
The inside barrel of the female socket has neat little integrated springs
and hold the male pin (w/ the black plastic tip) solidly.
The machine work looks very precision.. The plastic parts seem
solid and no special tool is needed to unplug the parts.
I'll post a report on how well they fit the UL-Solar panels, after I try them.