In recent years, with the rapid acceleration of the global energy transition, the solar photovoltaic (PV) industry has seen fast growth in the Americas. Whether it is large-scale ground-mounted solar farms in California and Texas or commercial rooftop PV systems in Mexico and Canada, the demand for reliable solar cables continues to rise.
In a solar power system, wires and cables are not just conductors of electricity-they are also critical to ensuring system efficiency, safety, and long service life. Choosing the right cable type directly affects the long-term operation cost and reliability of a PV installation.
Among various wire types, XHHW-2 wire has become one of the most widely used in North American solar installations due to its UL certification, high heat resistance, UV resistance, and moisture resistance. This article provides an in-depth analysis of the role of XHHW-2 wire in PV systems, compares it with THW wire, and helps EPCs, contractors, and buyers make the right selection.
What Is XHHW-2 Wire?
Definition and Standards
XHHW-2 is a UL-listed wire type commonly used in North America, defined under UL 44 standard. The designation stands for:
- X: Cross-linked polyethylene insulation (XLPE), excellent weather resistance
- HH: High Heat, continuous operation up to 90°C
- W: Suitable for Wet locations
- -2: Rated for 90°C in both dry and wet conditions
Voltage Rating
- Typically rated for 600V and 1000V, meeting both DC and AC wiring needs in PV systems.
Key Features
- High heat resistance, suitable for extreme climates
- XLPE insulation provides strong UV and weather resistance
- Flame-retardant properties meeting UL requirements
- Can be used in both dry and wet environments
- Long service life with reduced maintenance costs
Applications
XHHW-2 is commonly used for:
- DC side connections between modules and combiner boxes
- DC cabling from combiner boxes to inverters
- AC cabling from inverters to distribution panels
- Rooftop and ground-mounted solar installations in industrial and commercial facilities
Typical Applications of XHHW-2 Wire in PV Systems
DC Side Wiring
- Module-to-combiner box connections, typically 8–12 AWG copper
- Combiner box to inverter wiring, usually 4–6 AWG
AC Side Wiring
- Inverter-to-distribution panel cabling, ranging from 2 AWG to 500 kcmil
- Large solar plants often use aluminum XHHW-2 for cost efficiency
Outdoor Environments
- High UV exposure regions (e.g., California deserts): XHHW-2 maintains excellent UV resistance for long-term safety
- High humidity areas (e.g., Florida, Gulf Coast): XHHW-2 preserves high insulation resistance even in wet climates
Industrial and Commercial Rooftop PV Systems
- Widely applied in factories, universities, airports, and shopping centers with grid-tied solar installations
Comparison: XHHW-2 vs. THW Wire
THW wire is another common UL wire type, insulated with PVC and widely used in building wiring. However, when it comes to solar applications, XHHW-2 outperforms THW in many aspects.
| Feature | XHHW-2 Wire | THW Wire |
|---|---|---|
| Insulation | XLPE (Cross-linked Polyethylene), UV and heat resistant | PVC insulation, less durable under UV and weather exposure |
| Temperature Rating | 90°C in both dry and wet conditions | 90°C in dry, only 75°C in wet conditions |
| Outdoor Use | Excellent UV/weather resistance, ideal for solar farms | Degrades faster under direct sunlight, recommended for conduit or protected use |
| Moisture Resistance | Long-term reliability in wet environments | Limited performance in wet conditions |
| Typical Applications | PV systems, distribution wiring, outdoor use | Building wiring, indoor distribution, limited outdoor applications |
👉 Note: For North American solar power installations, XHHW-2 provides superior durability and reliability compared to THW, especially for long-term outdoor exposure under high UV and harsh weather conditions.
Why Is XHHW-2 Ideal for North American Solar Power Installations?
1.Compliance with North American Standards
- Certified under UL 44
- Meets NEC (National Electrical Code) PV wiring requirements
2.Versatile Environmental Adaptability
- Performs well in hot, dry climates (e.g., Arizona, California)
- Maintains safety in humid, rainy regions (e.g., Florida, Gulf Coast)
3.Safety and Reliability
- Flame-retardant insulation reduces fire hazards
- High insulation resistance enhances electrical safety
4.Economic Advantage
- Long lifespan reduces replacement frequency
- Lower total lifecycle operation and maintenance (O&M) costs
Common Specifications and Selection Guide for XHHW-2 Wire
Conductor Types
- Copper: Superior conductivity, ideal for high-performance systems
- Aluminum: Cost-effective, lightweight, suitable for large-scale projects
Size and Rating
- Conductor size: AWG 14 – 1000 kcmil
- Voltage rating: 600V / 1000V
- Available colors: black, red, blue, green, yellow, white (customizable)
Selection Reference Table
| Application | Recommended Size | Notes |
|---|---|---|
| Module to combiner box | 8–12 AWG | Short distance, small current |
| Combiner box to inverter | 4–6 AWG | Larger current, minimize voltage drop |
| Inverter to distribution panel | 2 AWG – 500 kcmil | Depends on system capacity |
| Rooftop commercial PV | Copper XHHW-2 | Higher conductivity and stability |
| Large-scale ground-mounted PV | Aluminum XHHW-2 | Cost-efficient, suitable for bulk use |
Choose Our Company-Dongguan Greater Wire & Cable Co., Ltd.
- Product Advantages: We specialize in UL-certified wires and cables, offering a full range such as THHN, THW, MC Cable, AC Cable, and more under our UL Wire series.
- North America Market Compliance: All products meet UL & NEC standards, ensuring suitability for PV systems across the Americas.
- Complete Specifications: Covering all common sizes and models for different solar applications.
- Strong Delivery Capability: Fast shipping, with support for both small and large batch orders.
- Service Excellence: Professional technical support with reliable pre-sales and after-sales service.
- Global Cooperation: Years of manufacturing and export experience, with partners worldwide.
- UL Certification: All products certified for quality and safety assurance.
- Customization Options: Tailored solutions in materials, sizes, lengths, colors, performance, marking, and packaging.
Customer Guidance & Contact
In North American solar power installations, XHHW-2 wire is the preferred choice for safety, durability, and long-term performance.
By choosing us, you will benefit from:
- A complete UL wire and cable product line
- Stable supply chain with fast delivery
- Professional engineering and technical support
- Global cooperation experience and guaranteed quality
📌 Contact Us
Dongguan Greater Wire & Cable Co., Ltd.
- Tel/WhatsApp/Wechat: +86 135 1078 4550 / +86 136 6257 9592
- Email: manager01@greaterwire.com