Solar Panel Connectors: Past and Present Trend

Solar modules link together through multiple combinations. They link the power optimisers or inverters to generate immense power. The connection of individual units is owed to solar wire connectors. 

Though you will come across three different solar panel connector types – MC4, MC3, and T4 – MC4 has already taken over MC3 and T4 connectors. No other connector apart from MC4 is used now. 

It all began during the early 2000s when new solar wire connectors with direct connectivity were launched. However, they posed certain limitations, like sensitivity to corrosion and breakdown due to mechanical stress.

Moreover, only highly trained technicians could handle these connectors based on the guidelines of the National Electrical Code.

The lack of feasibility downgraded their use, which led to the manufacturing and release of solar panel connectors types MC3 and T4. 

Though they addressed many problems, two issues persisted: the requirement for highly trained technicians and the opening of the connectors under load.  

With these problems in view, the National Electrical Code required solar wire connectors lacking these complications. It guided the production of the currently used ‘positive locking’ solar wire connector – MC4. 

MC4 connectors do not open on their own no matter the load because of the positive lock mechanism. 

So we know the success story of solar wire connectors. But let’s understand the drawbacks of MC3 and T4 solar panel connector types in detail.

Why do T4 Connectors Belong to a Bygone Age?

Among the failed solar panel connector types, T4 connectors were launched under the guidance of the National Electrical Code; and hence, comprised a locking mechanism. 

Launched by Tyco International Limited, this connector design was incompatible with the photovoltaic panels of that time. 

The workers could not plug in the T4 connectors in the extension cable due to the absence of specific terminals. It did not have positive and negative terminals between the plug and socket. The endeavour of connectivity required extra effort, whose solution was already available in the market, leading to decreasing their usage.

What did MC3 Connectors Lack?

MC3 connectors were also released under National Electrical Code directions. However, the manufacturers did not focus on a possible nuisance. To remove the requirement for technicians, they made the wire locks easy to open. However, their ease worked on stretch and heavy load, leading to connectivity and wear and tear problems. 

Moreover, MC3 varied from other solar panel connector types by providing IP65 protection and features like a maximum load of 1000 volts and a current capacity of 30 amperes. The IP65 connectors were unfit for locations with extreme weather conditions, specifically those witnessing floods. 

The extreme obstacles led to the abolishment of MC3 solar wire connectors, which eventually gifted us with MC4 solar wire connectors. So, let’s learn more about the saviour of solar wire connectors, MC4. 

MC4 Solar Wire Connectors

Multi-Contact 4 mm2 pins or MC4 pins revolutionised the use of solar wire connectors. Countering all the previous drawbacks, they provided IP67 protection and a locking mechanism to prohibit unintentional unplugging. MC4 solar panel connector types proved durable and resilient, thus expanding their applicability. 

The weather, water, UV and dust resistance, and quality material added a feather to its cap for better transmissibility.

After looking into the advantages, the next section deals with accessories and features required for MC4 installation. 

Specifications of MC4 Solar Solar Wire Connectors

MC4 solar panel connector types are suitable for a wide range of solar panels irrespective of the latter’s size in dimensions and power generation. Concerning power generation, these connectors can control and operate the resultant voltage. 

The accessories of MC4 solar wire connectors are of two types, interchangeable and non-interchangeable. 

  • – The interchangeable parts include a seal retainer, rubber water seals, and a screw on the end cap. 
  • – The non-interchangeable items comprise metal crimp and main housing. Another important component is safety lock clips to inhibit automatic disconnection. 

Handling MC4 connectors is also very easy. The required tools are a disconnect and spanner wrench, hinge and swing-out crimp tool with a contract holder. 

Furthermore, while installation, ensure usage of only National Electrical Code and Underwriter’s Laboratory certified cables for good strength and connectivity. 

Read on to know how to use these tools and specific add-ons of connectors.

Mechanism of MC4 with Power Systems

The only in-use connector among various solar panel connector types, MC4, enables series and parallel connections. 

  • – Series connection is easily possible with the direct positive and negative terminal connection. 
  • – The parallel connection requires multi-branch connectors. The multi-branch connection further requires male and female connectors. 

A combiner box is utilised to avoid confusion in the connectivity of multiple photovoltaic arrays, providing male and female outputs. 

The outputs directly or obtained from the combiner box are connected with power. Quality extension cables are needed for power sources placed at long distances. 

The same positive and negative terminal in the form of male and female connectors in the extension cable facilitates easy joining with solar wire connectors. 

Extension cables are cost-effective as they hold provisions to cut the cables as per the requirement, and the remaining one still functions. 


In the era of MC4 solar panel connector types, MC3 and T4 are outdated. The wide applicability and resistivity against numerous environmental and mechanical problems make MC4 the winner. 

When buying and installing solar panels, you must insist on the use of original MC4 connectors only. 


1. What is the purpose of solar wire connectors?

Solar wire connectors are required to connect solar modules or panels and microinverters, power optimisers, or power systems. 

2. Does the market provide only original solar wire connectors?

Both original and fake MC4 solar panel connector types are available in the market. Ensure that the connector being used for the installation of your system is original. 

3. Do I need additional things while connecting the solar wires connectors?

Two additional tools are required while connecting the solar wires to the power systems. The tools are crimp and combo tools, along with an extension cable.