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Premium bare copper stranded wire and related products engineered for solar PV array wiring, grounding, and interconnection systems.
As global solar photovoltaic (PV) capacity surpasses 1.5 terawatts and continues to expand at an unprecedented pace, the choice of wiring material within solar panel arrays has never been more critical. Bare copper stranded wire — composed of multiple fine copper conductors twisted together without insulation — has emerged as the definitive solution for grounding, bonding, and inter-panel interconnections in both residential rooftop systems and utility-scale solar farms. Its unmatched electrical conductivity (IACS ≥ 100%), superior flexibility, and proven long-term reliability in outdoor environments make it the preferred choice of solar EPC contractors, system integrators, and electrical engineers worldwide.
Bare copper stranded wire consists of multiple individual copper strands — ranging from 7 to over 600 strands depending on the AWG gauge — twisted together to form a single flexible conductor with no outer insulation or coating. This construction gives the wire exceptional flexibility compared to solid copper wire, making it far easier to route through conduit, along racking systems, and between panel junction boxes in complex solar array configurations.
In solar panel array wiring, bare copper stranded wire serves three primary functions: equipment grounding conductors (EGC), which protect personnel and equipment by providing a low-impedance fault current path; grounding electrode conductors (GEC), which connect the array grounding system to earth ground; and bonding conductors, which electrically connect all metallic components of the racking and mounting structure to eliminate dangerous potential differences.
🔆 Key Insight: The National Electrical Code (NEC), IEC 60364, and most international PV installation standards specifically permit or require bare copper stranded wire for solar array grounding and bonding applications — making it not just a best practice but a regulatory requirement in many jurisdictions.
The "stranded" construction is particularly important in solar applications because arrays experience continuous thermal cycling — expanding and contracting with daily temperature swings of 40–80°C — as well as wind-induced vibration. Solid copper wire is prone to work-hardening and fatigue cracking under these cyclic mechanical stresses. Stranded wire, by contrast, distributes mechanical stress across all individual strands, dramatically extending service life in outdoor photovoltaic environments.
Understanding the critical specifications ensures optimal performance and code compliance in every PV installation.
Electrolytic tough pitch (ETP) copper with ≥99.9% purity delivers IACS conductivity of 100%+, minimizing resistive losses across large solar array wiring runs.
Multi-strand construction (Class B, C, or D per IEC 60228) provides outstanding flexibility for routing through tight conduit bends and complex racking geometries.
Bare copper naturally forms a protective patina layer that resists atmospheric corrosion, ensuring decades of reliable service in exposed outdoor solar installations.
Stranded construction absorbs daily thermal cycling stresses, preventing work-hardening and conductor fatigue failure common in solid wire applications.
Available from #14 AWG to 4/0 AWG (and metric equivalents 1.5 mm² to 120 mm²) to meet every grounding, bonding, and interconnection requirement.
Manufactured to ASTM B8, IEC 60228, UL 4703, and NEC Article 690 requirements, supporting global solar project approvals and certifications.
The explosive growth of the global solar photovoltaic market is creating an unprecedented surge in demand for high-quality bare copper stranded wire. According to the International Energy Agency (IEA), solar PV is the fastest-growing electricity source in history, with annual additions exceeding 300 GW. Each megawatt of installed solar capacity requires approximately 1–2 tonnes of copper wiring for grounding, bonding, and electrical interconnection — translating to hundreds of thousands of tonnes of copper wire demand annually from the solar sector alone.
China, the United States, India, and the European Union are the four largest solar markets, collectively accounting for over 70% of global annual installations. In each of these markets, bare copper stranded wire is a mandated component of compliant solar electrical systems, creating a stable, growing, and geographically diverse commercial opportunity for quality copper wire manufacturers.
Emerging technologies and evolving installation practices are reshaping how bare copper stranded wire is specified and deployed in solar PV systems.
As solar projects scale from residential rooftops to multi-hundred-megawatt ground-mount farms, grounding conductors are required in larger gauges (2/0, 3/0, 4/0 AWG and above) with higher strand counts for improved flexibility during installation across vast field areas. Xingma's advanced wire-drawing and stranding machinery supports production of these large-format conductors at scale.
Agrivoltaic installations (solar panels co-located with agricultural land) and floating solar systems on reservoirs and water bodies introduce unique wiring challenges: higher humidity, exposure to water, and proximity to corrosive agricultural chemicals. Bare copper stranded wire's natural corrosion resistance and flexibility make it particularly well-suited for these demanding emerging applications.
Building-integrated photovoltaics (BIPV) — where solar modules are incorporated directly into building facades, roofing materials, and skylights — require ultra-flexible, small-diameter bare copper stranded wire that can be routed through extremely tight architectural spaces. This trend is driving demand for higher-strand-count conductors with Class D or finer stranding.
The rapid adoption of battery energy storage systems (BESS) paired with solar arrays creates additional copper wiring requirements for DC bus connections, battery bank grounding, and inverter interconnections. Bare copper stranded wire serves as the backbone of these hybrid solar-storage systems, handling both high-current DC paths and grounding networks.
Modern solar installations increasingly incorporate smart monitoring, power optimizers, and IoT-connected devices. These systems require robust grounding networks — built with bare copper stranded wire — to prevent ground loops, reduce electromagnetic interference (EMI), and protect sensitive electronics from lightning-induced transients and power surges.
Pilot offshore floating solar projects in coastal and marine environments represent a frontier application requiring the highest-grade bare copper conductors with exceptional corrosion resistance. Xingma's annealed copper wire with controlled surface quality meets the stringent requirements of these harsh-environment installations.
The EGC is arguably the most critical safety component in any solar PV system. It provides a continuous, low-impedance path for fault currents — such as those caused by insulation failures, lightning strikes, or arc faults — to return safely to the source, enabling overcurrent protective devices (OCPDs) to operate and clear the fault. Bare copper stranded wire is the preferred EGC material because its high conductivity ensures that fault currents reach sufficient magnitude to trip breakers or blow fuses before dangerous voltages develop on exposed metallic surfaces.
In a typical utility-scale solar farm, the EGC network consists of bare copper stranded wire running continuously along each row of panels, connected to every module frame, racking member, and combiner box enclosure. This creates a comprehensive equipotential bonding network that protects maintenance personnel from electric shock hazards even during fault conditions.
The grounding electrode conductor (GEC) connects the solar array's grounding system to one or more grounding electrodes — typically ground rods, ground rings, or concrete-encased electrodes — buried in the earth. For large solar farms, a perimeter ground ring of bare copper stranded wire (typically 2/0 or 4/0 AWG) is installed around the entire array boundary, with ground rods driven at regular intervals. This system provides a robust, low-resistance earth connection that dissipates lightning energy, limits step-and-touch voltages, and stabilizes system voltage reference.
Each solar module frame must be electrically bonded to the mounting structure to prevent dangerous voltage buildup in the event of a ground fault. Bare copper stranded wire jumpers — typically #6 or #8 AWG — are used to bridge any gaps in the bonding path caused by anodized aluminum racking components (which may have insufficient conductivity at mechanical connections). This application demands wire with excellent flexibility and reliable termination characteristics, both hallmarks of high-quality stranded copper conductors.
Solar arrays are prominent structures in open landscapes, making them vulnerable to direct and indirect lightning strikes. A properly designed lightning protection system (LPS) for a solar farm uses bare copper stranded wire as the primary down-conductor material, connecting air terminals (lightning rods) mounted on racking structures to the buried grounding electrode system. The high current-carrying capacity and low inductance of large-gauge bare copper stranded wire enables it to safely conduct the enormous peak currents (up to 200 kA) associated with direct lightning strikes without damage.
DC combiner boxes aggregate the output of multiple PV strings and represent critical nodes in the solar electrical system. The combiner box enclosure, its internal busbars, and all associated conduit must be grounded with bare copper stranded wire to protect against shock hazards and ensure proper operation of ground fault detection circuits (GFDIs) — a mandatory safety feature in modern solar inverters. The wire must maintain reliable contact resistance at terminal connections over decades of thermal cycling.
| Application | Typical AWG / mm² | Stranding Class | Key Requirement |
|---|---|---|---|
| Equipment Grounding Conductor (EGC) | #6 – 2/0 AWG / 16–70 mm² | Class B or C | Low impedance, continuous bonding |
| Grounding Electrode Conductor (GEC) | 2/0 – 4/0 AWG / 70–120 mm² | Class B | High current capacity, corrosion resistance |
| Module Frame Bonding Jumper | #6 – #10 AWG / 6–16 mm² | Class C or D | Flexibility, compact termination |
| Lightning Down-Conductor | 50 – 95 mm² | Class B | Peak current withstand (≥200 kA) |
| Combiner Box Grounding | #8 – #4 AWG / 10–25 mm² | Class B or C | Reliable terminal contact, GFDI compatibility |
| Perimeter Ground Ring | 2/0 – 4/0 AWG / 70–120 mm² | Class B | Continuous earth ring, step voltage control |
Bare copper stranded wire powers critical wiring needs across solar, automotive, communications, heavy industry, and new energy sectors.
5 Years of Excellence in Copper Wire Manufacturing for Solar, Industrial & Electrical Applications
Zhejiang Xingma Co., Ltd. was established in 2019 and is located in Liushi, the capital of electrical appliances in China. It is an enterprise mainly engaged in metal products, wire and cable processing and sales; import and export of goods and technology. The company revolves around the construction of a modern enterprise mechanism and mass production of mechanical automation.
The leading products include copper wire, copper braided wire, copper stranded wire, soft copper stranded wire, brush wire, carbon brush wire, soft connection series products, metal stamping parts and other products. Best-selling at home and abroad, deeply trusted and welcomed by customers. The company abides by the Universal Declaration of Human Rights and major United Nations conventions, respects human and labor rights, and is brave and determined to achieve and surpass itself.
State-of-the-art production infrastructure ensures consistent quality for every solar panel array wiring project.
Zhejiang Xingma Copper Industry Co., Ltd. has a factory building with a construction area of more than 10,000 square meters and more than 100 employees. It has more than 300 domestic top-level manufacturing machines, ensuring consistent, high-volume production of bare copper stranded wire for solar panel array wiring and industrial applications worldwide.
Main equipment includes: Dingtian wire drawing machine, Fuchuan beam machine, pipe twisting machine, braiding machine, annealing furnace, middle drawing machine, automatic cutting machine, welding machine, air dryer, microscope hardness tester, automatic punching machine, 160-ton punching machine, wire dividing machine, flattening machine, large polishing machine, stamping parts cleaning machine, bench drill, packing machine, and more.
With an annual production capacity of more than 2,000 tonnes, Xingma is positioned to meet the growing global demand for bare copper stranded wire driven by the solar energy revolution.
Modern manufacturing facility with full production lines for copper wire drawing, stranding, annealing, and finishing.
Domestic top-level automated manufacturing equipment ensuring precision, consistency, and high output volumes.
Experienced engineering and production team dedicated to quality copper wire manufacturing and customer service.
High-capacity production supports large solar farm projects, OEM customers, and global distribution partners.
Licensed for import and export of goods and technology, supplying solar and industrial customers across 50+ countries.
In-house testing with microscope hardness testers, conductivity analyzers, and dimensional inspection equipment.
Identify whether the wire will serve as an Equipment Grounding Conductor (EGC), Grounding Electrode Conductor (GEC), module bonding jumper, or lightning protection down-conductor. Each application has different current-carrying capacity, flexibility, and installation requirements that influence the appropriate gauge and stranding class.
For EGC sizing, follow NEC Table 250.122 or local equivalent standards, based on the rating of the overcurrent protective device protecting the circuit. For GEC sizing, NEC 250.166 specifies minimum sizes based on the largest service-entrance conductor. Always round up to the next standard wire gauge when calculated sizes fall between standard AWG values.
Class B stranding (7–19 strands) is suitable for most grounding and bonding applications where moderate flexibility is required. Class C (19–37 strands) or Class D (37+ strands) stranding is recommended for applications requiring maximum flexibility, such as module frame bonding jumpers or wiring in confined architectural spaces. Xingma supplies all stranding classes to customer specification.
For standard outdoor solar installations, bare annealed copper (soft-drawn) provides the optimal combination of conductivity and flexibility. In coastal, marine, or high-humidity environments, consider tinned copper stranded wire (available from Xingma) for enhanced corrosion resistance. In underground direct-burial applications, bare copper is typically specified in conjunction with appropriate conduit or direct-burial-rated cable assemblies.
💡 Pro Tip: Always verify that your selected bare copper stranded wire meets the applicable standards for your project location — ASTM B8 (USA), IEC 60228 (International), or GB/T 4910 (China) — and request mill test certificates (MTCs) from your supplier to confirm compliance. Xingma provides full material traceability and testing documentation for all orders.
Explore our full lineup of copper wire and conductor solutions for solar PV grounding, bonding, and electrical interconnection.
