Brief Guide: MC4 Solar Connectors

The MC4 connector is used to connect the solar panel with the DC cable that transmits the DC power from the panel to the inverter. The crimping is done with a special MC4 crimping tool. All modern solar panels use the MC4 solar connector. These connectors have an IP68 degree of protection. This means they are water and dust resistant. They perform well on 4mm and 6mm solar wire. Disconnecting them at any time will neither damage the connection nor the solar cable to which they are attached.


Top MC4 Connector Manufacturer


Staubli MC4 Connector

The MC4 solar connector was originally pioneered by a Swiss company called Staubli (formerly Multi-Contact). Multi-Contact has created specially shaped solid copper strips for electrical contact called MULTILAMS. These strips create several specific current-carrying contact points where electrical contact can be made.

In addition to this, there are several premium brands that manufacture MC4 connectors, namely Elmex, Bizlink, and KukaCable.

Elmex MC4 Connector

– They are made of flame retardant polymers that can withstand UV exposure.

– Elmex panel connectors are used in photovoltaic equipment such as DCDB (Direct Current Distribution Block), inverters, etc. It is available for cable sizes 2.5 mm2, 4.0 mm2 and 6.0 mm2.

Bizlink MC4 Connector

– They are extremely durable and can withstand harsh weather and harsh conditions of use.

– They comply with current safety regulations and have a strong snapping and locking mechanism that prevents them from separating under load.

– For outdoor settings, crimping and connector assembly equipment is available.

KukaCable Solar Connector

– Waterproof and durable for outdoor use with an IP68 rating.

– Strong compatibility, can match different cables 2.5mm-16mm.

– They are also insulated to prevent electric shock.

Additionally, the MC4 has MC4 Connector 4-in-1 and MC4 Connector 2-in-1 branch connectors. These varieties are used in large industrial projects and they allow you to connect 2 or 4 strings of solar modules to the same DC cable. Whereas a common MC4 connector is sufficient for residential connections.

What are the parts of an MC4 connector?

The MC4 connector consists of five components: a screw-in end cap, a rubber water seal, a seal retainer, metal crimp contacts, and the main housing. The last two components vary by male and female version of the MC4 connector.

Some MC4 connectors also feature a removable built-in security clip. They provide additional accidental disconnection safety by covering the interlock tabs.

How to install the MC4 connector correctly?

Installing the MC4 connector is very simple and can be done in a few minutes. Have your cables, MC4 connectors tools, wire strippers, wire crimpers, wrenches ready.

Step 1: Install the MC4 Connector

You'll see more wires being cut than metal crimp connections. The ideal length to strip the cable is about 1-2cm, insert the stripped wire into the male and female pins.

Step 2: Crimp the Cable

To provide a good connection and secure all components, you can use crimping pliers to crimp the male and female connectors. Crimp tools are easily available online.

Step 3: Pass the Crimp

The metal crimp must pass through before the screw. Otherwise, you won't be able to remove it without breaking the plastic case, since it has a non-return clip.

Step 4: Insert the cable

You will hear a "click" when you insert the crimped cable into the connection. Non-return clips secure the crimp into the plastic housing.

Step 5: Rubber Washes

You'll notice the cable's rubber grommet runs parallel to the plastic fingertip. Tighten the cap with a wrench until there are no gaps.

Step 6: Female Connector

Similar to the male in step 2, crimp the terminals of the connector and insert into the corresponding female connector and tighten the cap.

Step 7: Connect the Connector

Again, put the cable before the nut (as in step 3). As in step 5, check the rubber gasket. Simply push the male and female connectors together until you hear a "click".

Step 8: Testing

Before connecting to your solar panel, we recommend that you check the integrity of the wires with the new MC4 connector.

Remember, never unplug the solar panel from the inverter or battery, or while the sun is shining, as doing so may injure you.

Why are connectors so important?

Use a lot. In photovoltaic systems, connectors are used from components, inverters to engineering sites. A 1MW photovoltaic system will probably use 2000~3000 sets of connectors according to the power of the components used.

  • The potential risk is high. Each set of connectors contains 3 risk points (connection parts, positive and negative poles and cable crimping parts), which means that for a 1MW system, the connector may bring 6000~9000 risk points. In the case of current flow, the increase in the contact resistance of the connector will lead to an increase in temperature rise. If the temperature range exceeds the temperature range that the plastic shell and metal parts can withstand, the connector will easily fail or even cause a fire.

  • On-site O&M is difficult. Most of the existing monitoring software can only monitor to the string level. For specific faults in strings, on-site troubleshooting is still required. This means that if there is a problem with the connector, it must be checked one by one. For industrial and commercial power stations (color steel tile roofs), operation and maintenance are more difficult. Workers need to climb on the roof and manually lift the panels, which is time-consuming and laborious.

  • Power loss is large. The connector itself does not produce energy, it is the transmitter of energy. In the process of energy transmission, there will inevitably be losses. If calculated based on the average contact resistance of connectors on the market, a 50MW power station will lose about 2.12 million degrees of electricity due to connectors during the 25-year operation period.

The use of high-quality connectors not only saves maintenance costs and prolongs the service life of the product, but more importantly, it is safer to use and prevent fire accidents.

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