The MC4 connector is the best way to connect your solar panels to your battery bank. They are easy to use and require no tools. The connectors can be unplugged at any time without harming them or the wires they're connected with. In addition, these connectors allow for quick disconnection of power sources during emergencies, making them a must-have for anyone who enjoys living off the grid!
MC4 is the connection type name on all new solar panels, providing an IP67 waterproof and dustproof safe electrical connection. However, MC4 will not connect with older MC3 type connectors. The MC4 connectors work best with 4mm and 6mm solar cables.
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.
MC4 Connectors are incredibly common on solar panels. Generally, on most solar panels, two wires are coming off the back of the panel and terminating with a male and female MC4 connector. In order to extend these wires to reach your charge controller, you'll need to learn how to crimp MC4 connectors to make solar panel extension wires, and this blog post will teach you how to do that.
If you're asking this question, like how to use mc4 connectors , you've probably noticed that most modern high power solar modules are manufactured with wire leads that have MC4 connectors on the ends. Years ago, solar modules were built with a junction box on the back that required the installer to attach wires to the positive and negative terminal posts manually. This method is still used, but it's slowly becoming a thing of the past. Modern solar modules tend to use MC4 connectors because they make wiring your solar array much simpler and faster. The connectors come in both male and female types, which are designed to snap together. They meet the requirements of the National Electric Code, and they're UL certified and the preferred connection method of electrical inspectors. Due to the locking mechanism of the MC4 connectors, they will not come unplugged and are well suited for outdoor environments. The connectors can be separated, but it requires a special MC4 unlocking tool.
What is an MC4 Extension Cable?
MC4 connectors are single-contact electrical connectors. They are commonly used for connecting solar panels. MC4 stands for "Multi-Contact, 4 millimetres". It is a standard in the renewable energy industry. An MC4 connector enables the easy construction of strings of panels. In today's solar market, both MC4 connectors and their compatible products are used across the board. For the most part, larger solar panels will already come equipped with MC4 connectors. They are manufactured by Multi-Contact, which is the official manufacturer of MC4 connectors. Solar panels are plastic-based round housings with single conductors in paired male/female configurations. With the help of a notched interlock, MC4 connectors are able to terminate to each other and avoid being unintentionally pulled apart.
An MC4 connector is a waterproof, UV resistant, quick-connect (and disconnect) connector that can generally handle a max of 20A and 600V.
Don't feel bad if you're confused by the MC4 extension cables. If you've never worked with solar modules before, they can be a little intimidating. First of all, they're expensive. Nobody wants to purchase an expensive cable and later find out the length is too short after it's been cut. Cut cables cannot be returned, so we want to be sure you fully understand how to choose the appropriate length and how to use them to connect your panels together.
An MC4 extension cable is very similar in concept to an electrical extension cord. Just like an extension cord has a male plug on one end and a female plug on the other, an MC4 extension cable has a male connector on one end and a female connector on the opposite end. They are available in many different lengths, from 8 feet to 100 feet long. Let's go back to our first example of wiring two modules in a series. Once you've got the two modules connected in series, you need to use MC4 cables to bring that power to wherever your electrical equipment is located (usually a circuit breaker and a solar charge controller). Systems using two modules are generally used for RV's and boats, so you can usually use the extension cables along with the entire distance. However, when you use solar panels on a house or cabin, the distance that the wire must travel is normally so long that using an extension cable is no longer practical. In those situations, the extension cables are used to connect the panels to a combiner box. That way, you can use less expensive wiring (such as THHN rated insulation) inside the electrical conduit to cover greater distances at substantially less cost than the MC4 cables. Let's say that the total length of wire needed to go from the two modules to your electrical equipment is 20 feet. Note: This is where most people start getting confused. You only need one extender cable.
Extender cable in a 50-foot length, which is best suited for this situation. Remember that the two solar modules you've already connected have one positive lead with a male MC4 connector and one female lead with a female MC4 connector. To travel the 20-foot distance to your equipment, you will need a 20-foot wire with a male connector and a 20-foot wire with a female connector. This is achieved by cutting the 50-foot extension cable in half. That will give you a 25-foot wire with a male connector and a 25-foot wire with a female connector. That allows you to plug into both leads of your solar panel, and it gives you plenty of wire to get to your destination. Sometimes cutting the cable in half is not always the best solution. Depending upon the location of the combiner box, there may be a greater distance from one side of the panel string to the combiner box than from the opposite side of the panel string. In this case, you will want to cut the extender cable at a spot that allows both cuts ends to reach the combiner box with a little slack to work with.
When and where are MC4 connectors used?
Generally, this depends on the size of the solar panel. While they are all designed to be weather resistant and UV proof for reliable outdoor use, their different sizes serve different purposes. Smaller solar panels (less than 20 watts) do not produce high currents. Therefore, they are typically used as stand-alone units making the method of termination less significant. Larger solar panels (more than 20 watts), on the other hand, are designed to handle higher power levels. They are wired together in an array for standardized termination that can handle the greater voltage. As a result, the MC4 connectors must fit perfectly.
How many parts does an MC4 connector have?
Each MC4 connector has five parts. They are the main housing, a metal crimp contact, a rubber water seal, a seal retainer and a screw-on end cap. The male version of the MC4 connector uses a different housing and metal contact. The rest of its parts are interchangeable. In addition, some MC4 connectors have removable safety lock clips. They cover the interlock tabs and provide additional unintentional disconnect protection.
MC4 Connector – Positive vs negative
It's important to understand that there will be a male and a female connector on opposite ends of a wire. Male on one end of the wire, female on the other end. Pay attention to which is which and don't think "I always put male connectors on positive wires" because that would be incorrect. Instead, think of this like: "I need to connect to this 'male' connector, so I need to make a female mc4 connector here." (It's worth buying a few extra MC4 connectors because it's highly likely you'll mess this up a time or two.)
Characteristics of MC4 type connectors
We will only talk about MC4s for wire sizes 14AWG, 12AWG and 10 AWG, which are the same; since there is another MC4 for 8 AWG gauge cables that are not very common use. The main characteristics of the MC4 are the following:
- Nominal voltage: 1000V DC (According to IEC [International Electrotechnical Commission]), 600V / 1000V DC (according to UL certification)
- Rated current: 30A
- Contact resistance: 0.5 milliOhms
- Terminal Material: Tinned Copper Alloy
- Protection level: IP67 for female terminals and IP68 for male terminals.
- Upper limit temperature: + 105 ° (according to IEC)
Parts of an MC4 connector
We will divide this section in two since there are male MC4 connectors and female MC4 connectors, and it is very important to be able to differentiate them well both in the housing and in the contact sheets. The only things that MC4 connectors have in common are the gland connectors and the staples that go inside the MC4 to anchor the contact sheets.
We name MC4 connectors by the housing, not by the contact sheet, and this is because the contact sheet of a male MC4 is female and the contact sheet of a female MC4 is male. So BE VERY CAREFUL NOT TO CONFUSE THEM.
Parts of a male MC4 connector
The different parts of a male MC4 connector from a female one are the housing and the connection foil.
As can be seen, the case is a male connector, but the connecting plate is a female. The male MC4 connector is the one with the anchoring tabs and also has an O-Ring that is responsible for completely sealing the connection with the outside environment.
Parts of a female MC4 connector
The female MC4 connector receives that name from the housing, but as you can see, the connection plate is the one that is a male connection. This connector is where the tabs of the male MC4 connector housing are anchored.
These connectors are so special that you can see certain grooves in the female connection sheet (see figure 5) that make contact as clean as possible. This ensures that once we join the male connector with the female, it will be done an excellent contact.
How to Correctly install MC4 Connectors?
Cutting your Cable Length to Size
Trim your B&S cable length to size, or neatly trim the end off your Solar Panels Fly Leads using a set of Cable Cutters or wire strippers.
Undo the 'Screw Cap' of your first MC4 Connector
MC4 Connectors use 4 components to make a complete MC4 Connector.
Feed the Screw Cap onto the Cable End
(as per Example Below)
Ensure to feed your screw cap on the correct way, as you will need to remove this if you have it the wrong way around.
Feed the Cable Gland onto the Cable
Ensure to feed your screw cap on the correct way, as you will need to remove this if you have it the wrong way around.
Feed the MC4 Terminal / Pin onto the Copper Stripped end of the cable. Use a Crimper to crimp and secure the contacts of the terminal.
By Crimping the terminal onto the cable, you secure the copper cable to the contact for a secure power connection.
Feed the Main 'Male' Component of your MC4 Connector onto the cable as displayed in the image below.
The Screw components should meet in the middle, allowing you to screw and tighten the MC4 connector. Always ensure the MC4 Connector components are pushed to the end of the cable before attempting to secure the connector together.
Push the Initial Screw Cap down the cable to meet the MC4 connector, and tighten to form your secure connection.
After completing this install correctly, you should gently 'pull' at the MC4 connector, and it should feel secured onto the end of the cable.
What tools are necessary when working with MC4 connectors?
Those who work with MC4 connectors need to use a few different specialized tools. The most important of them all is a crimp tool and two disconnect/spanner wrench combo tools. A must-have on any crimping tool is a hinged, swing-out contact holder. It helps to make terminations uniform and on spec. It's wise to avoid any crimp tools without this feature.
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 to 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.
Frequently Asked Questions About MC4 Connectors
MC4 connectors are single-contact electrical connectors commonly used for connecting solar panels. The MC in MC4 stands for the manufacturer Multi-Contact (now Stäubli Electrical Connectors) and the 4 for the 4 mm diameter contact pin.
Wiring MC4 Equipped Modules in Series:
One wire is the DC positive (+), and the other is the DC negative (-). Generally, the female MC4 connector is associated with the positive lead, and the male connector is associated with the negative lead.
MC3 connectors have been largely superseded by MC4 connectors due to support being withdrawn by the National Electrical Code for solar applications. In addition, the MC3 connector does not incorporate a positive locking mechanism and can become disconnected while the solar panels are producing electricity, causing dangerous arcing.
Yes, the MC4 connectors are waterproof and can be disconnected repeatedly.
These solar panel connectors are available in male and female types made to snap together. Connectors are of various types, the major ones being MC3, MC4, PV and Tyco Solarlok. Similarly, they come in many shapes such as T-Joint, U-Joint, X-Joint or Y-Joint. However, the most common type of solar connector is the MC4 connector.