First, the photovoltaic connector to conduct good, contact resistance shall not be greater than 0.35 milliohms.

The Second, the need to have adequate safety performance, so as to protect the safety performance of solar modules. Solar equipment used in the environment, climate is sometimes in very harsh weather and environment, so there should be waterproof, high temperature, corrosion prevention, high insulation and other performance, the protection level should reach IP68.

Third, the solar connector structure to be solid and reliable, the correct pair of male and female connectors, the connection force between the two should not be less than 80 N. For the connection of 4mm ² cable MC4 connector, carrying 39A current, the temperature shall not exceed the upper temperature of 105 degrees. MC4/H4 connector is a single-core connector, male and female head, with a good seal, easy to connect, easy access, maintenance, etc. Many advantages.

The purchase of connectors should pay attention to product quality, including the size of the internal metal conductor compliance, material thickness, flexibility and plating should meet the ability to carry high currents and good contact, the connector shell plastic to ensure a smooth surface without cracks, the interface is well sealed. Component connectors should be installed to avoid sunlight exposure, rain, so as not to cause the connector aging, internal joints, cable rust, resulting in increased contact resistance, or even fire, resulting in a decline in system efficiency or cause fire accidents.

Photovoltaic connector installation, crimping link is the most important, should use professional crimping tools. Before the construction of photovoltaic power plants, the relevant engineering installation personnel should be trained in crimping operations.

With the development of photovoltaic cell technology, individual photovoltaic module capacity is also getting larger and larger, the string current is also gradually increasing, although theoretically MC4/H4 connectors are designed to carry current is sufficient to meet the requirements of these large-capacity components, but for a variety of reasons, in recent years, many photovoltaic power stations have seen an increasing number of connector meltdown, burn or even lead to convergence box, inverter burn accidents.

As we all know, a 100kWp scale of photovoltaic power station, there are usually 600-1000 such connectors, their contact resistance and other working conditions of the normal operation of the photovoltaic power station are very important. Connector working condition is poor, the light will affect the DC side of the internal resistance increases, resulting in power generation efficiency of the power plant decreased, the heavy is due to poor contact leads to connector heating or even burn the connector, which will lead to convergence box and inverter burn, more serious and even lead to a large area of fire.

There are uncertain risks (policy/technology/natural environment/legal, etc.) in all phases of PV plant evaluation, design, procurement, construction, building and O&M, which can affect PV system revenue if not properly controlled.

In the case of PV connectors alone, the technical risks are reflected in the quality, application, installation and O&M aspects.

It is important to note that the root cause of connector failure and thus fire: the contact resistance of the connector increases under current flow, resulting in an increase in temperature rise beyond the temperature range of the plastic housing and metal parts can withstand.

For photovoltaic connectors, 1996 and 2002 are two very important years. These two points in time also coincide with the key development points of the photovoltaic industry. Although photovoltaic connectors did not come with the PV industry, but its emergence on the rapid climb of PV installations played a greater role in promoting.

Prior to 1996, PV cables were connected using screw terminals or splice connectors. As the number of PV system installations increased, the need for fast, safe and easy-to-use connection solutions became stronger.

Because PV systems are exposed to rain, wind, sun and extreme temperature changes for long periods of time, connectors must be able to withstand these harsh environments. They must not only be waterproof, high temperature resistant and UV resistant, but also touch-protected, high current carrying capacity and efficient. At the same time, low contact resistance is also an important consideration. All of this must also be maintained throughout the life cycle of the PV system, at least 20 years.

In 1996, a new plug-in connector (MC3) was created based on these applications and market needs, the world’s first true photovoltaic connector, invented by the Swiss company Multi-Contact ( The main body of the MC3 is made of TPE material (thermoplastic elastomer), and the physical connection is achieved by frictional fit. Later, numerous connector manufacturers copied the MULTILAM technology.

In 2002, the MC4 was born to redefine the photovoltaic connector again, it truly “plug and play”. After the introduction of the MC4, it quickly gained market acceptance and gradually became the standard for PV connectors.

MC4 series connectors have been launched in line with the changing market demand, MC4-Evo2 and MC4-Evo3 series. MC4 series connectors have been fully able to meet the needs of customers for 1500V PV systems.

MC4 connectors are divided into wire-end and board-end, in the usual sense, we refer to the wire-end MC4, consisting of two major parts: metal parts and insulation parts.

As mentioned earlier, MC is the abbreviation of Multi-Contact, and 4 is the size of the metal core diameter. Therefore, in the PV connector market, a new clarification is needed for the many so-called MC4s, which might be more appropriately referred to as “MC4-like”.

In addition to some cosmetic differences (e.g. shape/logo, etc.), the core difference between MC4 and “MC4-like” is the use of MULTILAM technology, which has long-term stability and guarantees a consistently low contact resistance throughout the life cycle of the connector.

For marketing reasons, “MC4-like” claims to be interchangeable with MC4. Despite the appearance, it seems to complete the connection, but the invisible safety risks have already occurred. Different manufacturers’ connectors are not identical in terms of specifications, dimensions and tolerances, so they are simply not 100% compatible. If forced to interpolate, it will lead to temperature rise, contact resistance changes and IP rating can not guarantee the problem, and then seriously affect the resistance of power generation efficiency and safety.

What’s more, if there is a problem, it may lead to legal disputes. Since the relevant regulations are not sound, the responsibility for problems caused by interpolation is likely to be borne by the power plant installer.
Therefore, both TUV/UL and Multi-Contact have issued statements prohibiting the interpolation of connectors from different manufacturers.