PV transformers are core equipment in photovoltaic power generation systems, mainly used to convert DC output from PV inverters to AC and step up to connect to the grid. As the core material for PV transformer windings, the selection of copper foil directly affects the power generation efficiency, operational reliability, and investment returns of PV power plants.
I. Operating Characteristics of PV Transformers and Copper Foil Requirements
1.1 Operating Characteristics
Compared with ordinary power transformers, PV transformers have the following significant characteristics:
- Wide frequency range: PV inverter output frequency can fluctuate within 45-55Hz, requiring good frequency adaptability
- High harmonic content: Inverter output contains large harmonic components, transformers must withstand additional harmonic losses
- Large load fluctuation: PV power generation varies with sunlight intensity in real-time, causing severe transformer load fluctuations
- High temperature operation: PV power plants are generally located in high-irradiation areas with higher ambient temperatures
- Long life requirement: PV power plant design life is typically 25 years, requiring long-term stable operation
1.2 Core Considerations for Copper Foil Selection
| Technical Points | Requirements |
|---|---|
| Conductivity | IACS≥101%, reduce losses, improve efficiency |
| Thickness Accuracy | Tolerance within ±3% |
| Thermal Performance | Operating temperature 120-180°C |
| Fatigue Resistance | Stable performance under temperature cycles |
| Surface Quality | Smooth, defect-free |
II. Technical Specifications of Copper Foil Materials
2.1 Recommended Grades and Characteristics
| Grade | Copper Content | Conductivity | Tensile Strength | Elongation | Typical Applications |
|---|---|---|---|---|---|
| C11000 (ETP) | ≥99.90% | ≥101% IACS | 200-280 MPa | ≥15% | Standard PV Transformer |
| C10100 (OFC) | ≥99.99% | ≥101.5% IACS | 190-260 MPa | ≥20% | High-Performance PV |
| C10200 (TPA) | ≥99.95% | ≥101% IACS | 195-265 MPa | ≥18% | Special PV Applications |
2.2 Key Performance Parameters
Electrical Performance:
- Conductivity: IACS≥101% (annealed)
- Resistivity: 0.01724 Ω·mm²/m (20°C)
- Temperature Coefficient: 0.00393/°C
Geometric Dimensions:
- Thickness Range: 0.05-3.0mm
- Thickness Tolerance: ±0.02mm (high precision)
- Width Range: 10-600mm, customizable
Mechanical Properties:
- Tensile strength: 200-280 MPa (annealed)
- Elongation: ≥15-25%
- Hardness: 35-65 HV
- Surface roughness: Ra≤0.8μm
III. Special Process Requirements for PV Transformers
3.1 Harmonic Loss Control
PV inverters output high harmonic content, copper foil selection requires:
- Low eddy current loss: Appropriate thickness, typically ≤2.0mm
- High conductivity: Prioritize C10100 (OFC) high-purity copper
- Width design: Consider skin effect, width should not be too large for high-frequency harmonics
3.2 Heat Dissipation and Temperature Management
- High thermal conductivity: Copper thermal conductivity ~400 W/m·K
- Oil channel design: Inter-layer oil channel width must meet heat dissipation needs
- Temperature class: Recommended ≥180°C
3.3 Winding Process Parameters
| Parameter | Recommended Value | Explanation |
|---|---|---|
| Winding Tension | 10-20 N/mm² | Adjust according to foil condition |
| Winding Speed | 20-50 m/min | According to equipment capacity |
| Annealing Temperature | 400-650°C | Soften copper foil |
| Insulation Class | F (155°C) or H (180°C) | According to design requirements |
IV. Industry Standards and Certification System
| Standard | Description |
|---|---|
| IEC 60325 | Copper Foil for Transformers |
| IEC 60076 | Power Transformer General Requirements |
| GB/T 5231 | Processed Copper and Copper Alloys |
| ASTM B152 | Copper Sheets, Strips, and Foils |
V. Quality Inspection and Control
| Inspection Items | Testing Methods | Standards |
|---|---|---|
| Chemical Composition | Spectroscopy | Cu≥99.90% |
| Mechanical Properties | Tensile Test | Strength and elongation meet standards |
| Thickness Tolerance | Thickness Gauge | ±0.02mm |
| Surface Quality | Visual + Microscope | No cracks, inclusions, oxidation |
| Conductivity | Eddy Current | IACS≥101% |
VI. Supplier Selection Recommendations
- Full-process production line: Melting → Hot Rolling → Cold Rolling → Annealing → Slitting
- Thickness control accuracy: ±0.02mm
- Testing capabilities: Spectroscopic, mechanical, conductivity testing
- ISO 9001/14001/45001 certified
- Monthly capacity: ≥200 tons
VII. Product Specifications (Reference)
| Grade | Thickness | Width | Temper | Tensile Strength | Conductivity |
|---|---|---|---|---|---|
| C11000 | 0.1-2.5mm | 20-500mm | O/H22/H24 | 200-280 MPa | ≥101% IACS |
| C10100 | 0.05-2.0mm | 10-400mm | O/H22 | 190-260 MPa | ≥101.5% IACS |
| C10200 | 0.1-3.0mm | 20-600mm | O/H24 | 195-265 MPa | ≥101% IACS |
Conclusion
The selection of copper foil for PV transformers requires comprehensive consideration of harmonic environment, heat dissipation conditions, operating temperature, and cost-effectiveness.
Our company has 30 years of experience exporting electrical wire and metal foil. We provide C11000/C10100/C10200 series copper foil for PV transformers with customized sizes and global sample shipping.
Contact:
Email: office@cnlpzz.com
WhatsApp: 0086-19337889070
The technical parameters described are general reference values. Please consult our technical team for specific selections based on your PV transformer design requirements.