Solar Panel Voltage Calculator (NEC Compliant)

Solar Panel Voltage Calculator

Open Circuit Voltage (Voc) per Panel

Number of Panels in Series

Lowest Expected Temp (°F)

Standard Voltage (STC): 0V

Max Voltage (Cold Weather): 0V

*Cold temperatures increase solar panel voltage. Ensure your charge controller can handle the Max Voltage to avoid equipment damage.

Data Point	What it Means in American Solar Design
Voc (Open Circuit)	The maximum voltage a panel produces under no load. Use this to prevent frying your equipment.
Vmp (Max Power)	The “real world” voltage during active charging. Usually 15-20% lower than Voc.
Temperature Coefficient	In the US, solar voltage increases as it gets colder. A panel rated for 40V might hit 50V on a snowy morning in Montana.
NEC 600V/1000V Limits	Most US residential codes limit DC strings to 600V. Commercial systems go up to 1000V or 1500V.