Updated: Nov 4, 2019
Larger Solar panels that are designed to be wired together in an array need a standardized termination that can handle higher power levels. The MC4 connector fits the need perfectly. Most larger solar panels with a rating of more than 50 Watts come with MC4 connectors already on them. It provides an IP67 waterproof and dust-proof safe electrical connection.
MC4 stands for “Multi-Contact, 4 millimeters” and is a standard in the renewable energy industry. It is a round plastic housing with a single conductor in a paired male/female configuration developed by the Multi-Contact Corporation.
Have you considered making your own MC4 solar cables? Let me show you how easy it is.
In this tutorial, I will guide step by step so that in the end you will definitely make a professional MC4 Solar PV Cable.
Step 1: Tools and Materials Required
Working with MC4 connectors requires a few specialized tools.
Step 2: MC4 Connector Parts
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 Female version uses a different housing and metal crimp contact, but the rest of the parts are the same.
Step 3: Male and Female MC4 Connector
It's really confusing between FEMALE and MALE MC4 connectors because the one on the left clearly looks like a MALE and the one on the right clearly looks like a FEMALE.
The terminology relates to the crimp terminals inside the plastic housing not the physical body of the plugs. The plug on the right has the small MALE “pin” and the plug on the left has the FEMALE barrel/receptacle.
Note:Keep in mind that solar panels come with the female plug marked " + ", on the positive output lead from the solar panel.
Step 4: Strip Off the Cable Insulation
The maximum current and voltage that can be pushed into MC4 connectors depend on the type of wire used. I have written a tutorial on how to select the solar cable, you can go through it.
Standard Solar wire/cables are of size 10 AWG, 12 AWG and 14 AWG with an outer insulation diameter between 2.5 and 6.0 mm. The current-carrying capacities are as below:
10 AWG (6.0 mm) - 43A
12 AWG (4.0 mm) - 37A
14 AWG (2.5 mm) - 22.5A
Here I am using 12 AWG ( 4.0 mm).
The voltage rating of the cable is 1.5kV (1500V).
Strip the end of the cable insulation carefully by using a Wire Stripper. Be careful not to nick or cut the conductor.
The recommended cable stripping length is between 10-15 mm.
Step 5: Crimp the Connector
First insert the stripped wire into the crimp terminal, then place the terminal into the crimp tool dies. The open wing-ends of the terminal face up towards like the letter U as shown in the first picture above. Slowly squeeze the crimp tool until one or two ratchets click and the tool holds its position.
Step 6: Insert the Terminal Into the Main Housing
Once you’ve crimped the wire to the terminal you can then insert the terminal into the MC4 main housing. Before inserting the terminal, insert the end cap then press the crimped terminal into the housing until you hear it “click”. The contact has a barb and once inserted cannot be removed.
Step 7: Tighten the End Cap
First hand tighten the end cap into the main housing plug, then finish the job with your MC4 Spanner Set. When the end cap is tightened, the internal rubber seal is compressed around the outer jacket of the cable and thus, provides water-tight sealing.
The process for female MC4 connectors is the same but be sure to use the correct contact.
Now your MC4 connectors are ready to use. The finished product should look like as shown in the above picture above.
Step 8: Lock the Connectors
Push the Two Connector pairs together such that the two locking tabs on the MC4 Female Connector align with the two corresponding locking slots on the MC4 Male Connector. When the two connectors are coupled, the locking tabs slide into the locking slots and secure.
MC4 connectors allow strings of panels to be easily constructed by pushing the connectors from adjacent panels together by hand but require the MC4 spanner to disconnect them to ensure they do not accidentally disconnect when the cables are pulled.
Step 9: Unlock the Connectors
To disassemble /unlock the two connectors, press the ends of the locking tabs to release the locking mechanism and pull the connectors apart. Some time it is very difficult to disassemble by hand, you will require an MC4 Assembly & Disassembly Tool.
These are the tools used for snugging the MC4’s together. They are inexpensive, and worth having, especially for taking the terminals apart after they have been closed for a while.
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