String Sizing & Inverter Compatibility
Proper string sizing is critical for solar array performance and safety. Here's what you need to know when selecting components.
Key Factors in String Sizing
Panel Voc (Open Circuit Voltage) — must not exceed inverter's max input voltage
Panel Vmp (Maximum Power Voltage) — should be within inverter's MPP voltage range
Panel Isc (Short Circuit Current) — must not exceed inverter's max input current
Temperature coefficient — Voc increases in cold weather; size for lowest expected temperature
Number of panels in series — must stay within inverter's voltage window
Number of strings in parallel — must stay within inverter's current limits
How to Size a String
Determine the panel's Voc at STC (from the spec sheet)
Apply the temperature correction factor for your location's record low
Divide the inverter's max input voltage by the corrected Voc to get max panels per string
Check that the string Vmp stays within the inverter's MPP range
Verify the string Isc does not exceed the inverter's max input current
Verify total array power does not exceed inverter's max DC input
Common Compatibility Pitfalls
Mixing panel brands or models on the same string
Exceeding inverter max voltage in cold climates
Undersizing the inverter relative to array (high DC/AC ratio)
Using non-listed panel-inverter combinations for utility rebate programs
Not accounting for shading and mismatch losses
Tools & Resources
Most inverter manufacturers provide string sizing tools on their websites. We recommend using the manufacturer's official tool for their products.
Sizing & Compatibility Disclaimer
PES Supply provides product specifications and general guidance for informational purposes. However, system sizing, equipment selection, string configuration, and compatibility verification are the customer's responsibility. PES Supply is not liable for system underperformance, equipment damage, or code violations resulting from improper sizing or incompatible component selection. We strongly recommend consulting a licensed solar installer or professional engineer to confirm system design for your specific application, local climate, and code requirements.