Connector Components in Photovoltaic Systems

The development of photovoltaic power generation is rapidly accelerating toward the goal of carbon neutrality. From the PV module to the PV sink, from the PV sink to the inverter, and from the inverter to the grid, the entire PV system must bring the power together from many components. All links rely on cables and connectors, and PV connectors must not only be durable and able to withstand harsh environments but also meet the growing demand for electrical performance.

In all connector categories, we focus first and foremost on reliability. This is especially true for PV connectors, which should have the same life cycle as the entire PV system. Photovoltaic systems are exposed to rain, wind, sun, and extreme temperature changes over long periods. Connectors must not only be waterproof, high-temperature resistance, and UV resistance.

DC connection: improve reliability and reduce power loss

The international standard MC4 (MC4-like) connectors are widely used for DC connections throughout the PV system. In addition to international standards, individual countries or regions also have locally recognized industry standards. Standards for photovoltaic systems in the connector insulation strength, electrical clearance, IP protection level, and safety performance are clear requirements for the connector to meet these standards.

TUV/UL/JET three certifications represent the highest reliability of photovoltaic DC connectors, and currently, only Stäubli's original MC4-Evo 2 series can do DC 1500V TUV/UL/JET three certifications. Chinese manufacturer's more famous fast QC4.10-CDs series is 1500V TUV / UL dual certification, TE's SOLARLOK SLK 2.0 series is also TUV / UL dual certification, there are some manufacturers of TUV single certification can also reflect the reliability of the device enough.

Reliability is also reflected in the termination link, photovoltaic DC connector crimping technology inside a very large number of doorways. DC terminals to be crimped with professional tools. The reliability of crimping depends largely on the tools and operation. Most photovoltaic connectors are in the factory through automated equipment to complete crimping so that the quality will be relatively more secure.

After solving the risk of safety and reliability, lower contact resistance and improving energy transfer efficiency have been the direction of technological development of photovoltaic DC connectors. Lower contact resistance (<0.35mΩ) can guarantee efficient transmission capability of the device and significantly reduce power loss, contributing to reliable long-term operation. High contact resistance (e.g., defective material properties) can significantly reduce the device's efficiency.

Bus sink connection: eliminating sink boxes for safe electrical connections

The DC bus of the PV system is lined with dense wiring and appliances. The connection points in the sealed metal box environment will be relatively high in the box heat. Long-term operation is prone to electrical heating and other problems, which is not a small hidden danger.

Bus convergence This solution uses IPC insulated puncture connectors to connect PV modules in series and to the bus of convergence, directly replacing the DC bus box. Designed to eliminate the busbar connection scheme greatly reduces the PV module jumpers, and the overall cost is more advantageous.

The Insulation Piercing Technology IPC allows connectors to provide protection, insulation, and high-quality sealing for electrical connections without the need to strip the wire insulation before making the connection. Together with the fused PV fuse cable, the bus-bus convergence connection provides proximal protection for the PV module string.

In addition, the metal inserts of the insulated piercing connectors are wrapped in a sealed composite material, ensuring that the PV cables can withstand electrical connections of up to 1.5 kV DC.

AC Boost Connections: Safety Considerations for Medium and High Voltage Cable Intermediates

In AC booster stations, 35 kV medium voltage electrical systems and 110 kV/220 kV high voltage booster systems are commonly found. The voltage level of medium and high voltage products is relatively high, cable accessory products are prone to local discharge and breakdown problems, and the safety of medium and high voltage cable joints is the most important aspect of AC booster connections.

Usually, to ensure the cable's waterproof and other safety features, the cable's photovoltaic system as little as possible uses intermediate joints, mainly to avoid improper handling of cable joints, leaving safety hazards. If you want to use intermediate joints, be sure to use junction boxes, but also to ensure that the connection is not abnormal.

Heat-shrinkable cable joints use heat to shrink the insulation jacket and then wrap the cable tightly, thus achieving the sealing protection of the cable. Cold-shrink cable glands use elastomeric materials to compress the cable to achieve sealing protection. When used in AC step-up connections, the main consideration is the voltage resistance of these joints, which range up to 42 kV according to CENELEC HD 629.1, and up to 35 kV according to IEEE 404.

This ability to monitor and detect voltage will improve the reliability and safety of the entire PV connection system.

Final words

The safe operation of the PV system is a major concern. Every aspect of the entire connection system must be foolproof to ensure its safe and stable long-term operation to meet the requirements of PV system safety and reliability, connector selection and then consider the indicators related to efficient transmission to prevent problems before they occur.

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