Enter both values to calculate watts
Amps (A)
Volts (V)
Common:
Watts (W)
Result will appear here
Understanding the Relationship
The relationship between watts, volts, and amps follows the Power Formula:
- Power (P) = Voltage (V) × Current (I)
- Voltage (V) = Power (P) ÷ Current (I)
- Current (I) = Power (P) ÷ Voltage (V)
In Solar Systems
Understanding these relationships helps you:
- Size your wiring - Higher amps need thicker wires
- Choose inverters - Match wattage to your needs
- Configure battery banks - 12V, 24V, or 48V systems affect current flow
- Calculate loads - Know how much power your devices draw
Real-World Solar Examples
Verifying Panel Output
A solar panel producing 9.46A at 37.0V Vmp generates 350W. This is how manufacturers derive rated wattage from a panel's electrical characteristics on the datasheet.
48V Battery Bank Under Load
A 48V battery bank delivering 30A to an inverter is providing 1,440W of power. This tells you the load the battery is supporting at that moment.
Small Off-Grid Load
A 12V system drawing 8.33A from a battery is consuming 100W — a common scenario for off-grid loads like LED lighting or a laptop charger.
When You'll Need This Conversion
- Estimating Energy Consumption from Battery Monitor — If your battery monitor shows an average draw of 15A from a 24V bank, the system consumes 360W. Over 5 hours, that is 1,800Wh — which determines how many solar panels you need.
- Verifying Panel Performance with a Clamp Meter — You measure 8.1A from a panel at 36V, giving 291.6W. If the panel is rated 350W, it is operating at about 83% of STC rating — typical for real-world conditions.
- Calculating Total Array Power — Three panels each producing 10.8A in parallel at 37V give 32.4A total. Total power is 1,198.8W, helping verify the array performs as expected.
Solar Tips & Common Mistakes
Voltage Under Load Differs from Open-Circuit: When measuring current with a clamp meter, also read voltage at that moment. Using Voc instead of loaded voltage overestimates power output.
Battery Voltage Fluctuates with State of Charge: A "48V" battery bank may read 44V when discharged or 56V when full. Using 48V as a constant can give 15–20% error. Always measure actual voltage for real-time power calculations.
Parallel Strings Add Current, Not Voltage: Three parallel strings at 10A and 37V each produce 30A total but voltage stays at 37V. Total power is 1,110W, not 3,330W.
Solar Calculators
Related Conversion Calculators
Last updated: January 3, 2026
