Quick Answer
Determine the string length for solar panels by dividing the total system voltage by the maximum allowed voltage drop per string, considering the type of inverter and cable resistance. A common rule of thumb is to limit the string length to 1-2% of the total system voltage. This ensures efficient energy transfer and minimizes heat buildup.
Calculating String Length
To determine the maximum string length, calculate the total system voltage and the maximum allowed voltage drop per string. For a 48V system with 1% voltage drop per string, the maximum allowed voltage drop is 0.48V. Using a 10 AWG cable with 2.5% voltage drop per 100 feet, the maximum string length would be approximately 50 feet.
Inverter Requirements
Check the inverter manual for maximum string length guidelines. Some inverters have specific requirements, such as maximum string length or minimum string distance. For instance, a 60-cell inverter may require a minimum string distance of 1 meter to prevent overheating.
Practical Considerations
When designing the string layout, consider the physical constraints of the site, such as terrain, shading, and accessibility. Plan the string layout to ensure equal exposure to sunlight and minimize shading from nearby objects. Use a string length calculator or consult with a professional to ensure accurate and efficient system design.
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