Relationship Between RHW-2 Cable And UL 4703 in Photovoltaic Applications

With the rapid development of the global photovoltaic (PV) industry, the stability and safety of PV systems have become core concerns for project design and operation. In a PV power plant, the transmission of electricity from modules to combiner boxes and inverters relies heavily on high-quality cables. DC (direct current) cables are especially critical, as they carry the main system current and directly affect the energy conversion efficiency and operational lifespan of the system.

Among commonly used PV cables, RHW-2 and UL 4703 are two widely applied types. RHW-2 is known for its heat resistance and water resistance, making it a popular choice for electrical wiring. UL 4703, on the other hand, is specifically designed for PV systems, offering superior UV resistance, weather resistance, and high-voltage capacity. This article provides a detailed analysis of RHW-2 and UL 4703 in photovoltaic applications, including technical characteristics, application scenarios, and a comparative overview, along with practical recommendations and service advantages for informed cable selection.

Overview of RHW-2 Cable

Definition and Applications

RHW-2 (Thermoplastic Insulated Heat and Water Resistant Wire) is a thermoplastic insulated cable designed for high-temperature and wet environments. It is widely used in indoor, underground conduit, and partially buried wiring environments. In PV systems, RHW-2 is commonly applied between combiner boxes and inverters for DC wiring and can also serve as auxiliary wiring.

Technical Characteristics

• Rated Temperature: 90℃
• Rated Voltage: 600V / 1000V
• Flame Resistance: Meets UL 1581 VW-1 standard
• Weather Resistance: Suitable for conduit or partially buried applications; direct exposure requires protection

Practical Applications

• DC wiring from ground-mounted PV modules to combiner boxes
• Connections from PV inverters to combiner boxes
• Economical wiring solutions in conduit or semi-buried installations

RHW-2 cables offer reliability and cost-effectiveness, making them a preferred choice for small- and medium-scale PV projects.

Overview of UL 4703 Cable

Definition and Applications

UL 4703 is a DC cable standard specifically developed for photovoltaic systems. It is designed for long-term outdoor use and high-voltage applications. UL 4703 is typically used to connect PV modules to combiner boxes and can be directly exposed on rooftops or ground-mounted PV systems.

Technical Characteristics

• Rated Temperature: 90℃
• Rated Voltage: 1000V / 1500V
• Materials: Cross-linked polyolefin (XLPO) or high-durability polymer
• Weather Resistance: UV-resistant, ozone-resistant, water-resistant, and chemical-resistant

Practical Applications

• DC lines connecting PV modules to combiner boxes
• Direct exposure DC wiring in rooftop PV systems
• High-voltage 1500V PV systems, improving overall energy efficiency

UL 4703 cables are specifically engineered to withstand extreme outdoor conditions, ensuring the long-term stability of PV systems.

Performance Comparison of RHW-2 and UL 4703 (with THHN as Reference)

To provide a clearer understanding of the advantages and limitations of RHW-2 and UL 4703 in PV applications, THHN cable is used as a reference. THHN is a standard electrical wiring cable with heat resistance but lower weather and UV resistance.

Technical Analysis:

• RHW-2 is suitable for semi-buried or conduit-protected installations, offering cost efficiency.
• UL 4703 is ideal for long-term outdoor direct installations, with excellent UV and weather resistance.
• THHN is mainly for indoor wiring and is not suitable for outdoor PV applications.

This comparison helps customers select the most suitable cable type based on installation environment and cost considerations.

Specific Role of RHW-2 in PV Systems

• DC Wiring

RHW-2 cables are often used between PV modules and combiner boxes to transmit system current. Proper routing reduces power losses and enhances overall energy generation efficiency.

• Heat Resistance and Safety

RHW-2 has a rated temperature of up to 90℃, ensuring stable conductivity in high-temperature environments such as summer conditions or within conduits. Its flame-resistant properties comply with UL 1581 standards, providing safety during electrical faults.

• Long-Term Stability

RHW-2 offers good moisture and water resistance, suitable for underground or partially buried conduit installations, ensuring long-term reliability. This makes it an important economical wiring solution in PV systems.

Advantages of UL 4703 in PV Systems

• Adaptability to Extreme Outdoor Conditions

UL 4703 is specifically designed for outdoor PV applications, with resistance to strong UV radiation, ozone, and chemical corrosion, ensuring long-term reliability and reducing maintenance costs.

• High Voltage Capacity

UL 4703 cables support 1500V PV systems, reducing the number of series-connected modules and increasing overall energy generation efficiency. They are suitable for large ground-mounted or rooftop PV projects.

• Safety and Reliability

UL 4703 cables are UL certified, meeting North American and international safety standards, providing excellent flame and heat resistance for safe PV system operation.

Product Advantages and Service Features

• Product Variety: We Specialize in UL Wires and Cables

We offer THHN, THW, MC Cable, AC Cable, UL 4703, and other products, covering PV systems, industrial wiring, and building electrical wiring needs.

• Compliance with the Americas Market

All cables are UL certified, meeting North American and South American PV project standards and safety regulations.

• Full Range of Specifications

From 12 AWG to 500 kcmil, accommodating different current and installation requirements, ensuring project execution success.

• Fast Delivery: Support for Bulk and Small Orders

Sufficient stock and efficient logistics ensure on-time delivery for projects of any scale.

• Service Advantages: Professional Technical Support + Worry-Free Pre- and After-Sales

We provide wiring design, product selection guidance, and after-sales support, ensuring a seamless customer experience.

• International Cooperation: Years of Manufacturing and Export Experience

We have successfully participated in numerous PV and industrial projects, establishing long-term global partnerships.

• UL Certified

Our RHW-2, UL 4703, and other series cables comply with international safety standards, ensuring high reliability.

• Full Color Range and Customization

We support customization in material, specification, length, color, performance, marking, and packaging to meet individual customer requirements.

Practical Applications and Recommendations

• Ground-Mounted PV Power Plants

UL 4703 cables are directly laid between modules, achieving efficient wiring and long-term outdoor use.

RHW-2 is used between combiner boxes and inverters, reducing cost while ensuring reliability.

• Rooftop PV Systems

UL 4703 is suitable for direct rooftop DC wiring due to excellent UV and weather resistance.

RHW-2 is suitable for conduit-protected auxiliary wiring, balancing economy and safety.

• Summary of Comparison

RHW-2 is cost-effective and heat-resistant, suitable for semi-buried or conduit-protected wiring. UL 4703 is UV- and weather-resistant, ideal for outdoor direct installations. Choosing the optimal combination according to project budget, wiring environment, and system voltage maximizes PV system efficiency.

Company Information and Contact

Dongguan Greater Wire & Cable Co., Ltd.

• Tel/WhatsApp/WeChat: +86 135 1078 4550 / +86 136 6257 9592
• Email: manager01@greaterwire.com

We provide high-quality, full-spec UL wires and cables, with extensive experience in PV projects and global client collaborations. Whether for large-scale PV power plants or industrial electrical installations, we offer professional technical support and comprehensive customization services to ensure project success.