We use these MC4 type connectors on our hydro turbines and our React solar water pumps.
They provide a waterproof durable connection when used with 4mm² solar PV wire.
They are sold in male and female pairs and can be attached to the wire with any good 4mm² barrel crimp tool. We have a video showing how to use these connectors on our Youtube channel @reactpump . This video also shows how you can use fencing pliers and a drill bit to crimp these connectors. This method is suitable if you have only a few connections to make.
We recommend purchasing the Slocable connector tool which makes tightening the glands and breaking these connections easily.
Note: if wiring your own system in NZ, you can do so for voltages up to 120 VDC (ELV) if you have suitable knowledge and experience. For LV systems (>120 VDC) this is prescribed electrical work and it must be done by a licenced electrician.