Analysis of Cable Selection Factors in Photovoltaic System
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September 21 11:48:38, 2025
This paper provides a comprehensive overview of cable selection and design methods in photovoltaic (PV) systems. It explores the key factors that should be considered when choosing cables, how to select appropriate cables for different environmental conditions, and the essential principles that govern cable size specifications. Proper cable selection is crucial for ensuring system efficiency, safety, and longevity.
When selecting cables for a PV system, several important factors must be taken into account. These include the insulation properties of the cable, its heat resistance and flame-retardant characteristics, moisture and UV protection, installation method, type of conductor (copper or aluminum), and overall cable size. Each of these elements plays a critical role in determining the suitability of a particular cable for a specific application.
Different components within a PV system require distinct types of cables due to varying environmental conditions and performance requirements. For instance:
1. **Connection between PV modules**: Cables used here must pass UL testing, withstand temperatures up to 90°C, resist acid and chemical exposure, and be waterproof and UV-resistant.
2. **Wiring between battery and inverter**: These connections can use multi-strand cables that meet UL standards or electric welder cables that also pass UL tests.
3. **Connection between PV arrays**: These cables can be installed above ground or buried, but they need protection against moisture and sunlight. It’s recommended to use conduit rated for 90°C heat resistance.
4. **Indoor wiring (dry environment)**: For shorter DC connections, standard indoor wiring may be acceptable.
In terms of cable sizing, the following guidelines are generally followed:
1. **Short-distance DC connection from battery to indoor equipment**: The selected cable's rated current should be at least 1.25 times the continuous current.
2. **Internal array-to-array connections**: The cable’s rated current should be 1.56 times the maximum continuous current.
3. **AC load connections**: The cable's rated current should be 1.25 times the maximum continuous current.
4. **Inverter connections**: Similar to AC loads, the cable's rated current should be 1.25 times the calculated maximum continuous current.
5. **Temperature effects**: Cable performance can be affected by ambient temperature, so this factor must be considered during selection.
6. **Voltage drop**: The voltage loss along the circuit should not exceed 2% to maintain system efficiency.
7. **Cable diameter selection**: This depends on both current capacity and voltage drop. A common formula used is:
**Line Loss = Current × Circuit Length × Cable Voltage Factor** (provided by the manufacturer).
By carefully considering all these aspects, engineers and installers can ensure safe, efficient, and long-lasting PV system performance.