Most of the larger solar panels with a power rating of more than 50 watts already have MC4 connectors. MC4 is the name of all solar panel connection types, which stands for “4mm multi-contact”. It is a circular plastic housing developed by Multi-Contact Corporation, with a single conductor in a pair of male/female configurations, and provides an electrical connection with IP68 waterproof and dust-proof safety. MC4 connectors are most suitable for 4mm and 6mm solar cables.
Have you considered making your own MC4 solar cable? Let me tell you how easy it is.
In this guide, I will guide you step by step so that you will be able to make a professional MC4 solar photovoltaic cable in the end.
Some special tools are required to use the MC4 connector.
There are five parts of an MC4 connector (from left to right in the photo above):
1. End Cap
2. Strain Relief
3. Rubber Water Seal
4. Main Housing
5. Metal crimp contact
The mc4 female connector uses different shells and metal crimp contacts, but the rest are the same.
Note: Keep in mind that solar panels come with the female plug marked ” + “, on the positive output lead from the solar panel.
Use solar cable strippers to carefully strip the end of the cable insulation. Be careful not to scratch or cut the conductor.
You will find that the wire stripping distance is shorter than that of a metal crimp connector. There is a mark on the metal that indicates how far the other connector will be inserted into the connector. If the cable extends beyond the mark in the connector, the MC4 connectors will not be able to be connected together.
The recommended cable stripping length is between 10-15 mm.
We use an MC4 2.5/4/6mm crimp connector for this because it provides a good connection every time and fixes all bits in place during crimping.
(Crimp tools can be purchased from Slocable)
First insert the stripped solar wire into the crimping terminal, and then put the terminal into the crimping tool mold. The open wing-shaped end of the terminal faces upwards like the letter U. Slowly squeeze the crimping tool until one or two ratchets click into place and the tool maintains its position. We made a slight bend on the cable to achieve better surface contact inside the crimp.
There is a non-return clip inside the plastic shell. If you don’t put the nut on the cable first, you cannot remove the plastic shell without damaging it, resulting in unsafe use.
After crimping the solar wires to the connector terminals, the terminals can be inserted into the MC4 main housing. Before inserting the terminal, insert the end cap, and then press the crimped terminal into the housing until you hear a “click” sound. The contacts are barbed and cannot be removed once inserted.
Tighten the end cap into the main housing plug by hand, and then use the MC4 wrench kit to complete the work. After the end cap is tightened, the internal rubber sealing ring will compress around the cable jacket to provide a watertight seal.
The connection process of the MC4 female connector is the same, but please make sure to use the correct contacts.
Push the two connector pairs together so that the two locking tabs on the MC4 female connector are aligned with the two corresponding locking slots on the MC4 female connector. When the two connectors are coupled, the locking lug slides into the locking groove and is fixed.
The MC4 connector allows the panel string to be easily constructed by pushing the connectors of the adjacent panels together by hand, but an MC4 wrench is required to disconnect them to ensure that they are not accidentally disconnected when the cable is unplugged.
To remove/unlock the two connectors, press the end of the locking tab to release the locking device, and then pull the connector apart. Sometimes it is difficult to disassemble manually, you need to use MC4 assembly and disassembly tool (MC4 wrench).
These are the tools used to tie MC4 tightly together. They are cheap and worth having, especially when the terminals are closed for a while and then taken apart.
We recommend that you use the new MC4 connector to test the continuity of the cable before connecting to the solar panel or charge controller.
This will confirm that you have a good connection and will last for several years.
Remember, when the sun is on your solar panel or connected to the battery, do not disconnect the connector, otherwise you may be injured by the electricity.
If you still don’t understand how to operate, you can watch the following video demonstration: