That is an MPPT Smart Solar Charge Controller connection...You'll need to do some googling because there is a lot of info to assimilate..
Help to Identify AC Connector
Could anyone please assist me in identifying this AC connector? It is 5/8 x 1 inch and is on the output of a 24VDC 3kW inverter. (I need to purchase a matching male connector.) Any suggestions of part description and possible sources are welcomed. Thank you in advance for your help...