Executive Summary
Proper protection of photovoltaic inverters requires a comprehensive understanding of both DC and AC side protection strategies. This technical note provides detailed guidance on implementing effective protection schemes for residential, commercial, and utility-scale solar installations using Sinofuse gPV-rated components.
1. PV System Protection Architecture
1.1 System Overview
☀️ Complete PV System Protection Scheme
Multi-level protection ensures system safety and availability
1.2 Protection Zones
String Level Protection
Individual string protection prevents single string faults from affecting the entire array.
Recommended: PV312 Series, 15-20ACombiner Box Protection
Main DC protection before the inverter input, handling combined string currents.
Recommended: PV315 Series, 25-30AInverter DC Input Protection
Final DC side protection integrated within or adjacent to the inverter.
Coordination with string/combiner protection2. DC Side Protection Considerations
2.1 gPV Rating Requirements
🌞 Photovoltaic Specific
gPV rated fuses are designed for the unique characteristics of PV systems including reverse current and irradiance variations
🌡️ Temperature Cycling
Excellent performance under daily temperature variations typical in outdoor installations
⚡ High Voltage DC
Designed specifically for 1000V and 1500V DC system voltages common in modern PV installations
🔒 Long-term Reliability
25+ year service life to match PV system warranties and performance expectations
2.2 Fault Current Analysis
I_fault = 1.25 × I_sc × N_parallel
Where I_sc is short-circuit current and N_parallel is number of parallel strings
2.3 Coordination with System Components
📊 Selectivity Requirements
3. Sinofuse PV Product Selection
| Application | Product Series | Current Range | Voltage Rating | Key Features |
|---|---|---|---|---|
| String Protection | PV312 Series | 10-20A | 1000V/1500V DC | gPV rated, Fast-acting |
| Combiner Box | PV315 Series | 20-40A | 1000V/1500V DC | High breaking capacity |
| Central Inverter | PV320 Series | 50-200A | 1500V DC | Utility-scale applications |
| Residential Systems | PV310 Series | 10-25A | 1000V DC | Compact, cost-effective |
4. Installation and Maintenance Best Practices
✅ Best Practices
- Use only gPV-rated fuses for PV applications
- Ensure proper current derating for ambient temperature
- Implement coordinated protection strategies
- Plan for thermal management in combiner boxes
- Document protection coordination studies
- Schedule regular maintenance inspections
❌ Common Mistakes
- Using general-purpose fuses in PV applications
- Oversizing fuses for "extra safety margin"
- Ignoring temperature derating requirements
- Poor coordination between protection levels
- Inadequate consideration of reverse current
- Neglecting long-term performance monitoring
5. Performance Monitoring and Diagnostics
5.1 System Performance Indicators
📊 Current Monitoring
Continuous monitoring of string and main DC currents for early fault detection
🌡️ Temperature Tracking
Thermal monitoring of protection components and combiner boxes
⚡ Voltage Analysis
String voltage monitoring for detecting open circuits and ground faults
📈 Performance Ratios
Analysis of system performance ratios to identify protection-related issues
5.2 Preventive Maintenance Schedule
Recommended Maintenance Intervals
- Monthly: Visual inspection of protection devices
- Quarterly: Thermal imaging of connections and fuses
- Annually: Comprehensive system performance analysis
- Bi-annually: Protection coordination verification