MC4 Connector

Product Introduction

The MC4 connector (full name: Multi-Contact 4 mm) is a standardized quick-connect plug connector used for DC-side electrical connections in photovoltaic (PV) power generation systems. It was developed by Stäubli (formerly Multi-Contact) and has become the universal interface standard for DC wiring between modules, as well as between strings and combiner boxes/inverters in the PV industry. The “4 mm” in the name refers to the diameter of the core contact pin. The MC4 connector achieves tool-free connection through male-female mating and a self-locking latch. Its core electrical and safety performance must comply with the IEC 62852 standard.

I. Product Features

Tool-free quick-connect self-locking structure: When the male and female plugs are mated, the plastic locking tab inside the socket engages with the groove on the plug, and a “click” sound indicates that locking is complete. The connection is firm and resistant to vibration and accidental disconnection. A dedicated unlocking tool is required for disconnection; pliers or screwdrivers must not be used to pry it open forcibly, otherwise the housing and sealing may be damaged.

Low and stable contact resistance: High-end models use MULTILAM multi-contact technology, with a typical contact resistance of ≤0.25 mΩ, and maintain low and stable contact resistance over a service life of more than 25 years, reducing DC-side power loss. IEC 62852 specifies that the increase in contact resistance after testing shall not exceed 5 mΩ, or the final value shall be less than 150% of the initial value.

Wide voltage and current coverage: The rated voltage of basic MC4 models is usually 1000 V DC; the upgraded MC4-Evo 2 supports 1500 V DC systems, with rated current up to 30 A–45 A (depending on wire gauge and specific model), suitable for DC cable cross-sections of 2.5 mm²–10 mm².

Harsh-environment protection: When mated, the protection rating reaches IP65/IP68 (capable of short-term water immersion); when unmated, it is IP2X (finger-proof). The housing material is usually PC/PA, with UL94 V-0 flame retardant rating, UV resistance, and salt-spray corrosion resistance. The operating temperature range is -40°C to +85°C (upper limit up to 105°C).

Complete safety certification system: Mainstream products usually pass certifications such as TÜV Rheinland (IEC 62852) and UL 6703, and have a plug/unplug cycle life of more than 100 times.

II. Product Advantages

Significantly reduces DC-side line loss: Stable low contact resistance means lower Joule heat loss and smaller temperature rise, directly reducing power generation loss and lowering the risk of DC arcing caused by poor contact. This is the core value that distinguishes MC4 connectors from ordinary terminal connections.

High installation efficiency and strong on-site adaptability: Crimp contacts combined with quick-connect self-locking eliminate the need for terminal blocks or screw fastening, greatly shortening the DC wiring time of PV arrays and making the product suitable for large-scale rapid construction.

Protection and weather resistance match the 25-year plant cycle: The combined protection of IP68, UV resistance, and salt-spray resistance enables the connector to maintain electrical connection integrity on rooftops, ground-mounted plants, coastal areas, and high-humidity environments, reducing downtime maintenance caused by water ingress and oxidation of connectors.

System compatibility and maintainability: MC4 series products compliant with IEC 62852 have formed a mature interface ecosystem in the PV industry. MC4 interfaces on modules, combiner boxes, and inverters have a standardized mating basis, facilitating later operation and maintenance replacement.

III. Scope of Application

DC series connection between PV modules: Male and female MC4 connectors at the positive and negative lead ends of modules are mated with each other, forming the most basic DC connection node inside the array.

DC trunk line from strings to combiner box/inverter: The end of a string is connected to the DC input of a combiner box or string inverter through MC4 connectors, forming a complete DC circuit from the array to the equipment.

1000 V and 1500 V systems: Standard MC4 can be selected for conventional 1000 V DC systems; for 1500 V systems or high-voltage DC sides, MC4-Evo 2 or models explicitly rated at 1500 V DC should be selected.

Distributed rooftops and ground-mounted plants: DC-side wiring for residential, commercial and industrial rooftops, as well as large ground-mounted PV plants, all use MC4 interfaces as the universal solution.