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PV String Size Formula:
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PV String Size refers to the number of solar panels connected in series to form a string, calculated based on the maximum system voltage and the open-circuit voltage of individual panels.
The calculator uses the formula:
Where:
Explanation: This calculation determines how many panels can be safely connected in series without exceeding the system's maximum voltage rating.
Details: Proper PV string sizing is crucial for system safety, efficiency, and compliance with electrical codes. Undersizing can limit system performance, while oversizing can damage equipment and create safety hazards.
Tips: Enter the maximum system voltage and panel open-circuit voltage in volts. Both values must be positive numbers. The result represents the maximum number of panels that can be connected in series.
Q1: Why is maximum voltage important in string sizing?
A: The maximum voltage rating determines the upper limit for safe operation of inverters, charge controllers, and other system components.
Q2: Should temperature affect the calculation?
A: Yes, panel voltage decreases with higher temperatures. For accurate sizing, use the lowest expected temperature voltage or apply temperature correction factors.
Q3: What safety margin should be used?
A: It's recommended to include a 10-15% safety margin below the maximum voltage rating to account for voltage spikes and temperature variations.
Q4: Can different panel types be mixed in a string?
A: Generally not recommended. Different panels have different electrical characteristics that can lead to mismatches and reduced performance.
Q5: How does this differ from parallel connections?
A: This calculator determines series connections (voltage adds). Parallel connections (current adds) require different calculations based on current ratings.