What is An MC4 connector: A standard for Solar Panels

FACTS CHECKED BY  Jose George​

Solar panels are a common source of energy nowadays. With their help, you can turn on fans, lights, and even heavy electrical equipment. However, just like generators and other electrical machinery, these require connectors for smooth current flow. MC4 connectors have been made a standard in the renewable energy industry for such purposes. They are an integral part of any solar panel system. Then, what is an MC 4 connector?

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What are MC4 Connectors?

MC4 stands for “Multi-Contact, 4 millimeters”. These connectors have a single contact point and are common in attaching solar panels. Moreover, these enable easy construction of the row of panels. 

In most cases, the large solar panels have built-in MC4 connectors. These conductors are paired as Male and Female. Additionally, the presence of a notched interlock helps you to avoid pulling apart the connection, thus terminating the connectors successfully. 

What is An MC4 connector:MC4 Connectors with male and female components

Caption: MC4 Connectors with male and female components

When and Where MC4 are Used?

The MC4 connectors are designed to be UV-proof and weather-resistant. That way, they can provide a secure connection to the outdoor installations. However, their significance depends on how large the intended solar panel is. 

Small Solar panels cannot produce high current waves and are a stand-alone unit. That’s why termination is not necessary in the small branches. But, in larger setups of Solar panels, you have to handle higher power levels. In such cases, the connection between each panel has to be a perfect fit. Thus you need to focus on the MC4 connectors. 

As for the connection, the panels usually have 3ft of positive and negative wire. Each cable is terminated with MC4 connectors on one end and attached to the junction box. 

Moreover, the positive wire has the female connector, and the negative wire has the male connector of MC4. If you want to connect them, you just need to attach both the terminated ends to each other. 

In addition, if you want to extend the length of the wire, you will require an extension wire corresponding to be male and female MC4 electrical connector. 

How many Parts do MC4 connectors have? 

Every MC4 connector has five essential parts. These are

  1. Metal Crimp Contact
  2. Seal Retainer
  3. Rubber Water Seal
  4. Screw on the cap
  5. And Main Housing box

However, the only thing differentiating the male and female contact is their metal crimp design and housing material. Otherwise, all the parts are identical to each other. Also, some MC4 connectors have safety lock clips for covering the interlock tabs, thus providing additional security to the connection. 

How to Crimp MC4 solar Connectors?

To crimp the ends of the MC4 connectors, you will need some specific tools and materials. Other than that, it is easier than you thought. So, you will need

  • Wire
  • MC4 solar connector kit
  • Wire stripper
  • Wire connector
  • MC4 crimping and connector tool

As you get all the equipment, you can follow the following steps.

  1. Using wire cutters, cut the wire into the desired length.
  2. Next, strip the wire about ½ inch from one end using the wire stripper.
  3. Now, enter the stripped wire into the male pin and stiff it with the help of a wire crimping tool. After that, insert this pin inside a female MC4 connector and crimp again to fix the connection. 
  4. Repeat the same step with the female pin and male MC4 connectors. Make sure to crimp them hard so that the connection is secure. 
  5. In the end, check the female and male MC4 connectors by attaching them until you hear a click. Next, try to de-attach them and see if you can do it quickly. 

The last step is to check the correctness of all the other actions. If the wire doesn’t get loose in the previous step, you have done the job correctly. Otherwise, revisit steps 3 and 4 and repeat them until the connection has become solid. 

How to Wire MC4 Connectors in Series?

There are some panel setups where you put each module side by side. In such settings, the MC4 connectors are easy to connect. 

Look at the following figure

Here, you will see that there are two wires, tagged positive and negative, coming out of the junction box of each panel. Usually, people associate the female terminal with a positive lead and the male terminal with a negative lead. However, it might not always be the case. Hence you have to test the polarity before making the connection. 

To make the connection, you will connect the male terminal of one panel to the female terminal of the other solar panel. Once the wires click together, the current flow is regulated between the modules, as shown in the figure above.

How to Wire MC4 Connectors in Parallel?

Unlike series, connecting the MC4 terminals in parallel is tricky. You have to attach the negative terminal with the negative, and the positive terminal with the positive. The current will increase up to the maximum power in this method while keeping the voltage constant. 

Moreover, the setup will require an additional component, a Multibranch connector, since you cannot attach the terminals with the same design. The Multi Branch connector will allow you to connect both wires on the input end and terminate it with one port only, as shown in the figure. 

However, if you attach more than two panels, you will have multiple wires to connect in parallel. For that, you will need a PV Combiner box with the supported rating. Whatever PV box you choose, you have to see what is MC4 extension cable is and how to use it. 

What is An MC4 connector: Using MC4 Extension Cable

Like a simple electrical extension cord, an MC4 extension cable has a male connector at one end and a female at the other. Hence, you have to buy a wire of appropriate length for making the connection since you cannot trim it down by either side. 

When using solar panels in your home, the attached wire’s length is enough to reach the circuit breaker from the solar charge controller. However, if you cover more than a 20 ft area, you can do it with a 50ft extension cable. 

Cut the 50ft cable in half to be left with one female and one male wire. Then, attach it to the solar panel and extend the line to the point you want to make the connection. Also, you can use the same method to connect the system with the combiner box. 

What is An MC4 connector: Some More About MC4

When using the MC4, you are supposed to know about:

The science behind Male and Female Connectors

Identifying the male and female counterparts is not hard in standard cases. But as you take an MC4 connector, they might confuse you. 

The metal contacts inside the enclosure determine the gender. 

Here, the connector that you might think is male by appearance, is the female plug. Similarly, the one that appears to be female is the male plug. There are no standards that which one is positive and which is negative. However, in most cases, the female plug has positive polarity

MC4 connectors with a male and female counterpart

Caption: MC4 connectors with a male and female counterpart

MC4 Branch Combiner Connector

Combiners are used to connect the panels into one common field. With their help, you can combine two or more inputs into one output. Also, the number of inputs is not fixed if you do not exceed the current and voltage limits.

What is An MC4 connector: Disconnecting MC4 Connector

If you need to disconnect the MC4 terminals, all you can do is purchase a disconnecting tool. This tool will insert the extended posts into the Female MC4 connector and disengage the locking mechanism. 

The tool might come in a set of two, and you can use it together to completely de-attach the connectors. 

What is An MC4 connector: MC1, MC2, and MC3 connectors

At first, the connectors used for solar panels had extra wires coming out of them tied to other components in the junction box. But, these wires will become destroyed due to external weather effects. To overcome these, the National Electric Code NEC approved two new designs in 2000 that had simple rubber shielded jacks and sockets. These were called MC1 and MC3 designs. 

However, the MC1 and MC3 lacked locking mechanisms. Thus came the MC2 and MC4 design with ingress protection through positive locking in the market and still is popular among electricians.  

Conclusion

MC4 is the standard connector type that Solar panels use to connect the system. Also, you can create your connector cables by crimping the terminals onto the wire pieces. For that, you will need the right type of equipment. Here at Bloom, we offer a wiring harness, and your connection is made with attention to detail. 

Get a free Cable Assembly Quote.