The MC4 connector is divided into a wire end and a board end. Generally speaking, the MC4 refers to the wire end. MC4 is composed of two 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 photovoltaic connector market, many so-called MC4 need to be clarified again, they may be called "Compatible MC4" may be more appropriate.

In addition to some differences in appearance (such as shape / logo, etc.), the difference between MC4 and the "Compatible MC4" core is whether to use MULTILAM technology. MULTILAM technology has long-term stability, which can ensure that the connector maintains a continuously low contact resistance throughout the life cycle of the photovoltaic system.

"Compatible MC4" claims to be inter-insertable with MC4 for market reasons. Although the appearance seems to complete the connection, invisible security risks have already occurred. Connectors from different manufacturers are not consistent in terms of specifications, dimensions and tolerances, so they cannot be matched 100% at all. If forced to insert each other, it will cause problems such as temperature increase, contact resistance change and IP level cannot be guaranteed, which will seriously affect the power generation efficiency and safety of the resistor.

What's more serious is that if something goes wrong, it will most likely lead to legal disputes. Since the relevant regulations are not sound, the problems caused by inter-insertion are likely to be borne by the plant installer.

Therefore, both TUV / UL and Multi-Contact have issued a statement prohibiting the insertion of connectors from different manufacturers.

The technical risks of the connector

There are risks of uncertainty (policy / technology / natural environment / laws, etc.) in the various stages of the evaluation, design, procurement, construction, construction, operation and maintenance of photovoltaic power plants. If not properly controlled, it will affect the revenue of the photovoltaic system.

As far as photovoltaic connectors are concerned, the technical risks are reflected in quality, application, installation and operation and maintenance, as shown in the following figure.

It should be pointed out that the root cause of the fire caused by the failure of the connector: in the case of a flow, the increase in the contact resistance of the connector causes an increase in temperature rise, which exceeds the temperature range that the plastic shell and metal parts can withstand.