If you’re in the process of making a solar panel installation you will quickly come across something called an MC4 connector. These connections will be talked about in the instructions, plus you’ll see this listed in the product specification.
It is important to understand the terminology and how it works. This enables you to correctly hook up your solar array. Adding to this, you can ensure you buy compatible equipment such as adaptor cables and solar charge controllers.
Below we will discuss all of this including examples, differences, and how to use them correctly.
What is the MC4 Connector in Solar?
MC4 connectors are commonplace on most solar panels. They are the connections on the ends of the wires attached to a solar panel.
On the back of a solar panel you will see a junction box with 2 wires running out of it (one positive and one negative). At the end of these wires are your MC4 connectors.
You’ll notice that there is a difference between the connectors on each wire.
They look like this:
One has a long thin end, known at the ‘male’ end.
One has a square flat end with a hole known as the ‘female’ end.
And you’re right in thinking that the male end can plug into a female end. Don’t try to plug the solar panel wires into each other!
To hook up your solar panel to a charge controller, you will need another set of MC4 adaptor cables. These are wires with MC4 connectors on one end and connected to the charge controller at the other.
Generally, on solar panel wires, the positive side has a male MC4 connector and the negative has a female MC4 connector.
The opposite is then applied to the adaptor cables. The positive has a female end and the negative has a male end.
This is because you can only plug a male MC4 connector into a female MC4 connector. (and vice versa). Don’t worry, you can’t get this wrong as they won’t fit any other way!
Here’s a video to give you a visual understanding:
Are All MC4 Connectors the Same?
Yes, all MC4 connectors are universal. This means any two sets of these connectors will fit together. Any male MC4 fits into any female MC4.
This is useful if you are combining different solar products or installing the connections yourself.
You just need to be careful to check the positive and negative sides of your circuit. You always want to ensure you are connecting the positive to the positive and negative to negative. If your MC4 connectors are on the wrong wires you could easily make a mistake.
For example, a solar panel will have a male MC4 on its positive wire. This should connect to a female end on a positive adaptor cable. But if someone has stupidly attached a female MC4 to a negative adaptor cable, you could easily make a mistake!
Are There Different Sizes Of MC4 Connectors?
All MC4 connectors, adapters, and branches are the same size.
Which MC4 Connector is Positive?
Usually, the male end (long and thin) is on the positive wire of a solar panel.
The positive wire on the adapter cable, which runs to the charge controller, usually has a female end (flat with hole)
Which MC4 Connector is Negative?
Usually, the female end (flat with hole) is on the negative wire of a solar panel.
The negative wire on the adapter cable, which runs to the charge controller, usually has a male end (long and thin).
Do All Solar Panels Use MC4 Connectors?
Virtually all modern solar panels use MC4 connectors. This is because it makes wiring your equipment fast and easy. The male and female ends snap together without much effort. Plus it reduces the chances of making a mistake during installation.
Your solar panel should arrive with a junction box, cables, and MC4 connectors already attached. This means you won’t have to do any wiring yourself!
Are T4 Connectors Compatible With MC4?
You might also encounter T4 or MC3 connectors. These are rare but compatible with MC4.
You can use T4 connectors with MC4 connectors.
This is because MC4 connectors are proprietary designs created by a company called Multi-Contact (now Staubli). Other manufacturers create T4 connectors that work in the same manner.
Can You Reuse MC4 Connectors?
Yes, if you have MC4 connectors that you want to re-wire to a new set of cables then it is not an issue. As long as they are in good working order you can open the housing and take them off an existing wire. To reuse them, you just need to crimp each connector onto the new wires.
MC4 Connector Summary
MC4 connectors are designed to make hooking up your solar panels simple and fast.
When preinstalled on cables, you can avoid the need for stripping and crimping your wires. You can simply push and snap the male and female ends together. Once installed, they are completely waterproof and weatherproof so you can leave your array to work away without worries.
All of these connections are the same size and work seamlessly with one another. The only thing to double-check is that you are connecting positive to positive and negative to negative.
