MC3 connector

PV connectors MC3: Old-style Weatherproof DC connectors.

MC3 connectors are a fully discontinued type of single-contact connector commonly used for connecting solar panels. MC3 are named for the original manufacturer Multi-Contact (now part of Stäubli Electrical Connectors) with a 3 mm contact assembly pin.[1] They have a certification rating of 1KV (IEC) / 600V (UL) and 30A (10AWG PV Cable).