How to use Solar connector and solar extension cable

How to use Solar connector and solar extension cable

Note: there are many types of interlocking photovoltaic connectors. This article discusses MC4 connectors, but the same principle applies to other connectors, such as Amphenol H4, Tyco, and SMK.

What are MC4 connectors (male and female) and MC4 extenders (8ft, 15ft, 30ft, 50ft, 100ft)? If you ask this question, you may have noticed that most modern high-power solar panels are made of wires with MC4 connectors at the end. Years ago, there was a junction box on the back of the solar panel, and the installer had to manually connect the wires to the positive and negative terminals. This method is still in use, but it is slowly becoming the past. Modern solar modules tend to use MC4 connectors because they make your solar array wiring easier and faster. There are two types of joints, male and female, which are designed to be clamped together. They meet the requirements of the national electrical code and are UL certified. They are the preferred connection method for electrical inspectors. Due to the locking mechanism of MC4 connectors, they will not be pulled out and are very suitable for outdoor environment. The connector can be separated, but special MC4 unlocking tool is required.

Modules with MC4 installed in series:

If you have two or more solar modules in series, the MC4 connector makes it very simple. Take a look at the first module and you'll find that it has two wires that extend from the junction box. One wire is DC positive (+) and the other is DC negative (-). Generally, the female MC4 connector is connected to the positive wire and the male connector is connected to the negative wire. This may not always be the case, so it's best to look at the markings on the junction box or test the polarity with a digital voltmeter. Series connection refers to connecting the modules together by connecting the positive lead of one module to the negative lead of another module. The male connector will clip directly into the female connector. Here is a simple diagram to illustrate this.

As you can see, the two modules are now connected by two wires. This increases the voltage of the circuit. For example, if your module is rated at 18 volts at maximum power (VMP), then two modules in series will measure 36 VMP. If the three modules are connected in series, the total VMP is 54 volts. When wiring in series, the current at maximum power (IMP) will remain constant.

Parallel MC4 module: parallel connection requires positive leads to be connected together and negative leads to be connected together. This method will increase the current at maximum power (IMP) while keeping the voltage constant. For example, suppose your module is rated for 8 amp IMP and 18 Volt VMP. If two are connected in parallel, the total amperage will be 16 amperes and the voltage will remain at 18 volts. When two or more modules are connected in parallel, you will need some additional equipment. If only two modules are used, the easiest way is to use MC4 multi branch connector. Obviously we can't connect two male connectors or two female connectors together, so we use multi branch connectors to achieve this. There are two different multi branch connectors. One type accepts two external MC4 connectors on the input side and has an external MC4 connector for output. The other type accepts two female MC4 connectors and has one female MC4 connector for its output. Essentially, you've reduced the number of wires from two positive and two negative to one positive and one negative. This is a chart. You can see what it's doing.

If more than two modules are to be connected in parallel, or multiple module strings are to be connected in parallel, a device called photovoltaic combiner box is required. You no longer need a multi branch connector because the combiner box will perform the same function. The multi branch connector is only suitable for parallel connection of two modules. If more than two modules or series need to be connected in parallel, the combiner box is used. The total number of modules that can be combined will depend on the electrical rating and physical size of the combiner box. Whether you are combining modules with multi branch connectors or combiner boxes, you need to know how to select and use MC4 extension cables.

What is an MC4 extension cable? How do I use them?

If you're confused about the MC4 extension, don't be upset. If you've never used solar modules before, they can be a little scary. First of all, they are very expensive. No one wanted to buy an expensive cable, but later found that it was too short after being cut. The cut cables cannot be returned, so we want to make sure you fully understand how to choose the right length and how to use them to connect the panels together.

The MC4 extension cable is very similar in concept to the electrical extension cable. Just as there is a male plug at one end of the extension cable and a female plug at the other end, there is a male plug at one end of the MC4 extension cable and a female plug at the other end. They come in many different lengths, from eight to 100 feet long. Let's go back to the first example of two modules in series. Once the two modules are connected in series, an MC4 cable is required to transfer power to any location where the electrical equipment is located (usually a circuit breaker and a solar charging controller). Systems that use two modules are typically used for RV and vessel, so extension cables can usually be used along the entire distance. When you use a solar panel in a house or cabin, the distance that the wires have to go through is usually very long, so using an extension cable is no longer practical. In these cases, the extension cable is used to connect the panel to the combiner box. In this way, you can use cheaper wiring (such as then rated insulation) in the conduit to cover a greater distance at a much lower cost than the MC4 cable. Assume that the total length of the wires required from the two modules to your electrical equipment is 20 feet. Note: This is where most people start to get confused. You only need one extension cable. We offer a 50 foot extension cable that is best suited for this situation. Remember that the two solar modules that you have connected have a positive lead and a male MC4 connector, a female lead and a female MC4 connector. To move 20 feet to your device, you 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. This will give you a 25 foot wire with a male connector and a 25 foot wire with a female connector. This allows you to plug in two wires of your solar panel, which gives you enough wires to reach your destination. Sometimes cutting the cable in half is not always the best solution. Depending on the location of the combiner box, the distance from one side of the panel string to the combiner box may be greater than the distance from the other side of the panel string to the combiner box. In this case, you'll want to cut the extension cable where both cut ends are allowed to reach the combiner box, with a little slack. This figure shows an example of this scenario:

For systems using combiner boxes, you only need to select a length that is sufficient to terminate in the combiner box when cutting. You can then strip the insulation off the cut end and terminate it to the bus or circuit breaker.

Disconnect the MC4 connector:

This is a MC4 disconnect tool. If the MC4 cable needs to be disconnected for some reason, one of them is required. The two extension bars at the end of the tool must be inserted into the side of the female MC4 connector. This will separate the locking mechanism on the male connector and allow the two connectors to separate. The disconnect tool is sold as a two-piece set. If the connector needs to be removed, two tools are required. It's almost unnecessary. Generally speaking, you only need one tool.

If you have any questions about MC4 connector, multi branch connector, extension cable or combiner box, please call or email us. One of our design experts will be happy to help you.