MC4 Solar Connectors




Introduction: MC4 Solar Connectors

Ecoboris is about getting renewable energy working for you as a positive addition to your home.

MC4 is the name of the connection type on all new solar panels, providing an IP67 waterproof and dust proof safe electrical connection. MC4 will not connect with older MC3 type connectors.

The MC4 connectors work best with 4mm and 6mm solar cable.

When you buy any new solar panel (usually over 30 Watts) it will be already fitted with two 500 - 900mm leads with MC4 connectors attached for you to get the power safely out of the solar panel.

Great, but how do you get the power from the panel on an outbuilding roof to your controller 20 Metres away ?

You can buy pre cut leads from 2 Metres to 10 Metres, We sell these, but a more efficient way is to buy the cable which you can cut to the exact length you need and then attach MC4 connectors.

We offer a custom cut length cable with MC4 connectors fitted service, if you do not feel confident enough to tackle this yourself.

The picture above shows all the parts for the male and female connectors.

All you need is the cable, a male and female MC4 connector, wire strippers, some wire crimps and about 10 minutes of your time.

On to connecting..........

Step 1: MC4 Male Connector Fitting

You will notice the wire is stripped shorter than the metal crimp connector. There is a mark on the metal to indicate how far the other connector will enter into this one, if your cable extends past this mark in the connector you will not be able to join the MC4 connectors together.

Recommended cable stripping length is between 10 - 15mm.

On to crimping...............

Step 2: Crimp the Cable

We are using a MC4 2.5 - 4 - 6mm crimp connector for this because it gives a great connection every time and holds all the bits in place when you crimp.

The crimp tool is available from Ecoboris or widley available on the internet from £35

Thats the easy bit done now onto the even easier bit.....

Step 3: Nut on First

Pass the screw nut over the metal crimp first

The plastic housing has a non return clip inside and if you have not put the nut on the cable first you will not be able to get the plastic housing off without damaging it rendering it unsafe to use.

On to inserting the cable...................

Step 4: Insert the Cable

When you push the crimped cable into the connector, you will hear a "CLICK"

This is the non return clip locking the crimp into the plastic housing.

On to checking the rubber washer...................

Step 5: Rubber Washer

Looking closely at the picture you will see that the rubber seal washer is flush with the end of the plastic fingers around the cable.

This will give the best grip on 4mm cable when the nut is tightened onto the plastic housing.

If you do not do this with 4mm cable the connector will be able to spin around the cable and over time may damage the connection.

On to the female connector......

Step 6: Female Crimp

We put a little bend in the cable for better surface contact inside the crimp.

This cable insulation is stripped by 15mm to expose the wire for crimping.

Crimp the same as the male in step 2.

On to inserting the cable.................

Step 7: Insert the Cable

Again pass the screw nut over the cable first ( step 3 )

Check the rubber washer as in step 5

Then push the crimped cable into the female housing untill you hear the "CLICK"

Tighten the nut onto the female plastic housing.

Onto testing.............

Step 8: Test Before Connecting

We would advise you to test the continuity of your cable with the new MC4 connectors on before connecting to your solar panels or charge controller.

This will confirm you have a good connection that will last for years.

Please remember never disconnect the connectors when the sun is on your solar panels or they are connected to a battery, you may be injured by your free green electricity.

Stay safe and thank you for looking at our MC4 connection guide

Be the First to Share


    • Clocks Contest

      Clocks Contest
    • Block Code Contest

      Block Code Contest
    • Baking Contest

      Baking Contest


    Mike riley
    Mike riley

    Question 1 year ago

    What is causing my positive connectors from the panels to the optimizers to melt? I get non stop code 25 with fault on my solar edge inverter. T


    8 years ago

    Have to comment. This isn't a good instructable topic, you're just putting together a product.

    Aside, worthwhile to mention the MC4 crimper is a specialized tool, the Rennsteig model is ~$300. Also you have WAY too much wire stripped on the cable! Especially on the positive coupler side. The male pin will not reliably seat inside the female with that extra wire inside. I've seen connectors melt and fail due to arcs with this as the probable cause. Play safe.

    Mike riley
    Mike riley

    Reply 1 year ago

    I’m currently experiencing melted positive connectors from the panels to the optimizers. Panels connectors parts number positive side PV2A with no name brand. Same number on the negative connectors. Optimizers connectors are AMPHENOL with no other description. Are these connectors compatible? I’ve replaced ten optimizers out of twenty. Th


    Reply 8 years ago

    Thank you for your comment,
    We have received requests to show how the MC4 connectors are put together because we are not all installers and the connectors do not come with instructions.
    With low voltage DIY electrics we want our customers to feel safe with taking on a task that they are able to do but may be put off because of lack of instructions.
    We sell the MC4 crimp tool on our website for £48.99
    We show how the manufacturer advises to connect for best electrical contact connection.
    As we say this is a guide to help get renewable technology to any one who needs it.

    Many thanks


    2 years ago on Step 1

    That's the female part, not the male.


    Question 4 years ago on Introduction

    I'm racking my brain trying to increase the sun-hours on my panels (if and when i get them) in an area with a lot of tall evergreens. Probably the only real solution is to mount them in a tree. If this is a bad idea, please tell me. But my question is...what is the maximum length cable from the panels to the charge controller?


    Answer 2 years ago

    there isnt really a maximum length as long as your cable is thisk enough.


    Question 3 years ago on Step 4

    I can’t get the male connector to click into the housing. The female clicks in just fine. What am I doing wrong?


    6 years ago

    So what wire did you use? Can you take apart again, in case you put on the wrong connector? What are the pin and hole dimensions?


    7 years ago

    Thanks for sharing. This helped me.


    8 years ago

    Well, looks you updated the picture to now show a shorter length of stripped wire. Nice. Best of luck with your business ;)