1. Overview and Core Significance of PV Grounding Connectors

PV grounding connectors are special grounding and bonding components dedicated to photovoltaic power generation systems, mainly used to realize equipotential bonding and reliable grounding of non-current-carrying metal parts such as photovoltaic module frames, photovoltaic support structures, combiner box shells, inverter casings, and DC cable armor. Different from PV string connectors responsible for power transmission, PV grounding connectors do not participate in the normal power generation and current transmission of the system, but undertake the core safety protection function of the photovoltaic system. They are the key guarantee to prevent equipment damage, personal electric shock accidents, and system safety faults caused by lightning strikes, static electricity, leakage current, and circuit faults .

Photovoltaic systems are exposed to outdoor open environments for a long time, and metal components such as module frames and supports are extremely easy to accumulate static electricity due to atmospheric friction and electromagnetic induction. In thunderstorm weather, photovoltaic arrays, as large-area outdoor metal facilities, are prone to induce lightning overvoltage, resulting in equipment breakdown and damage. In addition, insulation aging, line damage, and component failure in the system will cause DC leakage current to conduct to the metal shell. Without reliable grounding protection, these residual voltages and leakage currents will lead to charged equipment shells, posing a serious threat to on-site operation and maintenance personnel and equipment safety .

PV grounding connectors can conduct static electricity, leakage current, and lightning induced current generated by the photovoltaic system to the earth in a timely and stable manner, realize equipotential bonding of all metal structural parts of the system, eliminate potential difference between equipment, avoid electric shock hazards and partial discharge phenomena, and effectively prevent lightning damage and electrical fire accidents. In the entire photovoltaic system safety system, the grounding system composed of PV grounding connectors, grounding wires, and grounding electrodes is the last line of defense for system operational safety, and its installation quality and operational reliability directly determine the safety level of the entire photovoltaic power station .

All global photovoltaic industry specifications and electrical safety standards clearly stipulate that all exposed non-current-carrying metal parts of photovoltaic systems must be reliably grounded through special PV grounding connectors. It is forbidden to rely on simple lap jointing of supports or ordinary bolts for grounding, because the contact resistance of simple lap jointing is unstable and easy to increase due to rust, oxidation and loose bolts, resulting in grounding failure. Special PV grounding connectors can maintain ultra-low and stable grounding resistance for a long time, ensuring the long-term effectiveness of the grounding system .

2. Classification and Structural Working Principle of PV Grounding Connectors

2.1 Main Product Classification

According to different application positions and structural forms, PV grounding connectors are mainly divided into photovoltaic module grounding clips, support grounding clamps, grounding lugs, and equipotential bonding connectors. Each type of product has a targeted structural design to adapt to different grounding scenarios of photovoltaic systems .

Photovoltaic module grounding clips are the most widely used grounding connectors, specially designed for the grounding of aluminum alloy frames of photovoltaic modules. Most module frames are equipped with anodized oxide layers on the surface, which have insulating properties. Ordinary bolt connection cannot realize effective conductive grounding. The grounding clip adopts a tooth-shaped piercing structure, which can pierce the surface insulating oxide layer of the module frame during installation, directly contact the internal metal matrix, and form a stable conductive loop. This type of connector has the advantages of simple installation, no need for drilling and wiring, and high construction efficiency, and is suitable for batch grounding of large-scale photovoltaic modules .

Support grounding clamps are specially used for grounding and equipotential bonding of photovoltaic aluminum alloy or steel supports. The support surface also has anti-corrosion insulating coating, and the grounding clamp adopts a double-sided tooth-shaped clamping structure, which can pierce the surface coating of the support, realize metal-to-metal direct contact, and complete the reliable grounding connection of the support system. It can adapt to different types of C-shaped steel, U-shaped steel and aluminum alloy supports, with strong universality .

Grounding lugs are conventional grounding connectors, mostly used for grounding connection of combiner boxes, inverters and other electrical equipment shells. They are fixed on the equipment grounding reserved holes through bolts, and connected with the grounding electrode through grounding wires to realize equipment grounding. Grounding lugs are mostly made of tinned copper material, with stable conductivity and strong corrosion resistance, suitable for fixed-point grounding of electrical equipment .

Equipotential bonding connectors are mainly used for electrical connection and equipotential balancing between multiple metal components of photovoltaic systems. They can connect module frames, supports, and equipment shells into a unified equipotential system, eliminate potential difference between different metal parts, avoid floating voltage and partial discharge, and improve the overall safety and stability of the system .

2.2 Core Structural Design and Working Principle

The core structural feature of all PV grounding connectors is the piercing conductive structure, which is the key to solve the insulation problem of metal surface anti-corrosion coating of photovoltaic components. The surface of photovoltaic module frames and supports is treated with anodization, spraying and other anti-corrosion processes, forming a dense insulating oxide layer and coating. If ordinary fasteners are used for connection, the insulating layer will isolate the metal matrix, resulting in open circuit or high resistance state of the grounding loop, unable to realize effective grounding .

PV grounding connectors are designed with high-hardness alloy tooth-shaped piercing points. When fastened with torque, the sharp tooth tips can pierce the surface insulating coating and oxide layer accurately and stably, and closely fit with the internal conductive metal matrix to form a low-resistance conductive channel. At the same time, the fastening structure can maintain continuous compression force, avoid poor contact caused by coating aging, peeling and component vibration, and ensure that the grounding resistance remains stable for a long time .

In terms of material structure, PV grounding connectors are mostly made of high-purity copper alloy or stainless steel with surface tin plating treatment. Copper alloy has excellent electrical conductivity, ensuring ultra-low grounding loop resistance; tin plating can effectively prevent the oxidation and corrosion of the connector surface, adapt to long-term outdoor humid and salt spray environment, and avoid the increase of grounding resistance caused by corrosion. The insulating gasket and fastening bolt components are matched to ensure mechanical fastening stability while avoiding electrochemical corrosion between different metal materials .

The working principle of the grounding system is as follows: when static electricity, leakage current or lightning induction voltage is generated on the metal parts of the photovoltaic system, the current can be quickly conducted to the grounding wire through the low-resistance channel formed by the PV grounding connector, and finally released to the earth through the grounding electrode. The equipotential bonding function makes the potential of all metal components of the system consistent, eliminates the potential difference that causes electric shock and discharge, and realizes comprehensive safety protection of the photovoltaic system .

3. Core Performance Requirements and Compliance Standards

3.1 Key Technical Performance Indicators

The core performance index of PV grounding connectors is stable low grounding resistance. Industry standards clearly require that the grounding resistance of photovoltaic system grounding loops must be less than 4Ω, and the grounding connector, as the core connection node of the grounding loop, must ensure that its own contact resistance is extremely low and does not increase significantly with time and environmental changes. Qualified PV grounding connectors can maintain a contact resistance below 0.1mΩ after long-term outdoor operation, ensuring the smooth conduction of grounding current .

Mechanical fastening stability is another key performance indicator. The grounding connector must maintain stable fastening torque under long-term outdoor vibration, temperature cycle changes, and wind load impact, without loosening and displacement. The standard fastening torque of module grounding clips is 225kgf·cm, which can ensure that the piercing teeth are closely attached to the metal matrix without falling off or failure . The tensile resistance of the connector meets the industry standard, and no separation or open circuit occurs under external tension, ensuring the continuity of the grounding loop.

Environmental adaptability performance determines the long-term service life of grounding connectors. PV grounding connectors need to pass salt spray corrosion test, ultraviolet aging test, damp heat aging test and temperature cycle test. They can resist salt spray erosion in coastal areas, high temperature aging in desert areas, and low-temperature frost crack in alpine areas, and maintain stable electrical conductivity and mechanical properties for more than 25 years, matching the service life of photovoltaic modules. The surface tin plating treatment can effectively prevent electrochemical corrosion and avoid grounding failure caused by connector rust .

In addition, the connector has good weather resistance and anti-aging performance, and will not deform, crack or fail due to long-term outdoor exposure. The insulating accessories have excellent insulation performance, which can avoid short circuit of grounding loop caused by external conductive substances and ensure the independent and stable operation of the grounding system .

3.2 International and Industry Compliance Standards

PV grounding connectors and system grounding construction must comply with strict international electrical safety standards and photovoltaic industry specifications. The core international standards include IEC 60364-7-712 low-voltage electrical installation photovoltaic system special specification and IEC 62548 photovoltaic array design standard. The standards clearly stipulate that all non-current-carrying metal parts of photovoltaic systems must be equipped with reliable equipotential bonding and grounding devices, and prohibit isolated independent grounding systems, requiring unified bonding of DC side and AC side grounding systems .

The North American market complies with NEC 690 photovoltaic system special electrical code and NEC 250 grounding system specification. NEC 690.43 clearly requires that all exposed metal parts of photovoltaic modules and equipment must be reliably grounded, and grounding connectors must pass UL 467 and UL 2703 certification to ensure product safety and reliability . The specification also clarifies the matching relationship between grounding wire specification and system overcurrent protection parameters, providing a clear basis for grounding system design and construction .

In terms of product certification, qualified PV grounding connectors must pass TÜV safety certification, UL certification and RoHS environmental protection certification. All products need to complete strict performance tests such as grounding resistance stability, mechanical vibration, environmental aging and corrosion resistance to ensure that they meet the long-term operation requirements of photovoltaic power stations. In the project acceptance link, the grounding system resistance and connector connection quality will be tested in strict accordance with the above standards, and unqualified projects are not allowed to be grid-connected for power generation .

4. Standard Installation Process and Construction Key Points

4.1 Pre-construction Preparation

Before the installation of PV grounding connectors, complete system grounding scheme design and material preparation shall be carried out first. According to the system scale, installation environment and industry standards, determine the type and quantity of grounding connectors, the specification of grounding wires (4-14AWG copper conductors), and the configuration scheme of grounding electrodes. For large-scale ground photovoltaic power stations, a unified grounding grid system needs to be built; for distributed rooftop photovoltaic systems, the building's original grounding system can be used for equipotential connection after verification .

Check the quality of grounding connectors and accessories before construction, confirm that the product certification is complete, the appearance is intact, the piercing teeth are sharp and free of damage, the bolts and gaskets are complete, and there is no oxidation and corrosion. Prepare professional installation tools, including torque wrenches, crimping pliers, resistance testers, etc., to ensure that the construction tools meet the standard requirements .

4.2 Standard Installation Steps

The installation of photovoltaic module grounding clips is the most common construction link. First, select the reserved grounding hole on the module frame (the frame is marked with a special grounding identifier, and it is forbidden to use mounting holes for grounding) . Place the grounding clip on the inner and outer sides of the frame, align the piercing tooth surface with the frame metal matrix, penetrate the bolt and fasten it with a standard torque wrench with a fastening torque of 225kgf·cm. After fastening, confirm that the piercing teeth are closely attached to the frame, no looseness or deviation, and complete the grounding connection of a single module .

For support grounding construction, install support grounding clamps at the overlapping positions of photovoltaic supports, fasten the clamps to make the double-sided piercing teeth penetrate the support surface anti-corrosion coating, realize metal conduction between supports, and complete the overall equipotential bonding of the support system. For combiner boxes, inverters and other electrical equipment, fix the tinned copper grounding lugs on the equipment reserved grounding bolts, and connect the grounding lugs to the system grounding main line through grounding wires .

After the installation of all grounding connectors is completed, carry out series connection of grounding wires to form a complete grounding loop, and finally connect the system grounding main line to the grounding electrode (grounding rod, grounding grid). After the construction is completed, use a professional grounding resistance tester to detect the system grounding resistance to ensure that the resistance value is less than 4Ω, meeting the safety operation standards of photovoltaic systems .

4.3 Construction Key Points and Prohibited Operations

In the construction process, it is strictly prohibited to use ordinary bolts and gaskets instead of special PV grounding connectors for grounding connection. Ordinary accessories cannot pierce the surface insulating coating of components, resulting in virtual grounding and hidden safety hazards. It is forbidden to damage the module frame coating at will for manual grounding, which will accelerate frame corrosion and affect the service life of components .

The fastening torque must be strictly controlled during installation. Excessive torque will crush the module frame and support profile, resulting in structural damage; insufficient torque will lead to incomplete piercing of the insulating layer, unstable contact and increased grounding resistance. The grounding wire routing should be neat and fixed firmly, avoiding excessive tension and exposure and abrasion, and the wire diameter selection must match the system overcurrent protection specifications .

For photovoltaic projects in coastal, high-humidity and high-salt environments, anti-corrosion treatment must be carried out on grounding connectors and wiring nodes after installation, and anti-corrosion grease is applied to prevent salt spray corrosion and ensure the long-term stability of the grounding system .

5. Common Faults, Hazard Analysis and Maintenance Strategies

5.1 Common Fault Types of Grounding Connectors

In the long-term operation of photovoltaic power stations, PV grounding connectors mainly have faults such as increased grounding resistance, loose fastening, corrosion and oxidation, piercing failure, and grounding wire falling off. Increased grounding resistance is the most common fault, mostly caused by incomplete piercing of insulating layer, connector corrosion and loose bolts. Loose fastening is caused by long-term vibration and temperature cycle changes, leading to poor contact of grounding nodes .

Connector corrosion and oxidation are prone to occur in coastal and humid areas. The surface tin plating layer is damaged and oxidized, resulting in increased contact resistance and even open circuit of grounding loop. Piercing failure is caused by insufficient installation torque or wear of piercing teeth, resulting in failure to pierce the surface insulating layer of components, unable to form effective conductive grounding channel. Grounding wire falling off is caused by unqualified crimping and loose fixing, resulting in grounding system paralysis .

5.2 Safety Hazards Caused by Grounding Faults

The failure of PV grounding connectors will lead to the failure of the entire photovoltaic system grounding protection function, bringing serious safety hazards. First, the equipment shell is charged, resulting in electric shock accidents for operation and maintenance personnel. The leakage current of the system cannot be released, and the metal parts of the module frame and support maintain a high potential, which will cause electric shock injury when personnel touch the equipment .

Second, lightning protection failure will occur. When thunderstorm weather comes, the induced lightning voltage of the photovoltaic array cannot be released to the earth, which will break down the insulation of modules and electrical equipment, burn components and inverters, and cause large-scale equipment damage. In addition, the floating potential of the system will cause partial discharge and arc phenomenon between metal components, which will ignite surrounding combustibles and induce photovoltaic power station fire accidents .

At the same time, the failure of the grounding system will also affect the normal operation of the inverter, resulting in frequent alarm and shutdown of the equipment, reduced power generation efficiency of the system, and bringing economic losses to the power station operation. Long-term ungrounded operation will also accelerate the aging of component insulation and shorten the overall service life of the photovoltaic system .

5.3 Daily Maintenance and Fault Handling Strategies

Establish a regular inspection and maintenance system for PV grounding connectors. Conduct a comprehensive visual inspection every quarter to check whether the connectors are loose, corroded, rusted or fallen off, and whether the grounding wires are damaged or aged. Conduct a comprehensive grounding resistance test every year to detect the resistance value of each grounding node and the overall system grounding resistance, and find and rectify abnormal resistance nodes in a timely manner .

For faulty connectors with increased resistance and loose fastening, re-fasten and adjust the torque to the standard value; for connectors with serious corrosion and oxidation and piercing failure, replace them with new qualified grounding connectors in a timely manner, and re-test the grounding performance after replacement to ensure compliance with standards. For photovoltaic power stations in harsh environments, increase the inspection frequency to twice a year, and do a good job in anti-corrosion and waterproof protection of connectors .

In the daily operation and maintenance process, it is forbidden to disassemble and modify the grounding connector structure at will, and it is forbidden to cut off the grounding wire without permission. After the module replacement and equipment maintenance of the power station, the grounding connection must be rechecked and tested to ensure that the grounding system is intact and effective .

6. Industry Application Value and Future Development Trends

PV grounding connectors are the core safety components of photovoltaic systems, and their application value runs through the whole life cycle of photovoltaic power station design, construction, operation and maintenance. A complete and reliable grounding system composed of high-quality PV grounding connectors can effectively avoid personal electric shock accidents, equipment damage and fire hazards, ensure the safe and stable operation of photovoltaic power stations, and reduce operation and maintenance risks and economic losses. With the continuous expansion of the scale of global photovoltaic power stations and the continuous improvement of system voltage levels, the safety requirements for photovoltaic grounding systems are becoming increasingly stringent, and the importance of PV grounding connectors is further highlighted .

In recent years, with the rapid development of distributed photovoltaic, rooftop photovoltaic, agricultural photovoltaic and fishing photovoltaic projects, the application scenarios of PV grounding connectors are more diversified, and the product adaptability requirements are higher. The industry is gradually developing towards specialized, customized and intelligent grounding connector products. Special grounding connectors for aluminum magnesium alloy supports, thin-film modules and special-shaped supports have been launched one after another, which can meet the grounding requirements of different types of photovoltaic systems .

In terms of technological innovation, new PV grounding connectors with anti-corrosion, anti-aging and self-locking functions have been popularized and applied, which further improve the long-term operational stability of the grounding system. At the same time, intelligent grounding connectors with resistance monitoring and fault alarm functions have begun to be applied in large-scale intelligent photovoltaic power stations, which can realize real-time online monitoring of grounding node status, accurately locate fault points, and greatly improve the intelligent operation and maintenance efficiency of the grounding system .

In the future, with the continuous improvement of global new energy safety standards, the industry threshold of PV grounding connectors will be further improved, and inferior products will be gradually eliminated. The products will develop in the direction of higher corrosion resistance, longer service life, simpler installation and higher intelligence, providing more reliable safety guarantee for the high-quality development of the global photovoltaic industry. As an indispensable safety core component of photovoltaic systems, PV grounding connectors will always play an irreplaceable role in the safe operation of new energy power generation systems .