Solar Panel Amps to Watts Calculator — PV System Sizing | Ampstowatt Guide
Solar current path
Panel watts converted into battery-side charging amps
Solar pages need separate panel-side and battery-side thinking, so this visual shows panel power moving through the controller before the amp result.
Quick answer
Use this calculator to separate panel-side current from battery-side charging current.
Solar systems can show different amps at the panel, charge controller, and battery. Enter the voltage point you are sizing so the result matches the wire, fuse, controller, or battery cable you are checking.
Inputs to check before calculating
- Use panel Vmp for panel-side string current.
- Use battery bank voltage for battery-side charging current.
- Account for MPPT or PWM controller efficiency before selecting fuses or wire.
- Check controller current ratings above the calculated output current.
Example: 1,200 watts at 12 volts
At 12 volts, a 1,200 watt load draws 100 amps before AC power-factor adjustments. Use the power factor field when the equipment is a motor, compressor, inverter, or other inductive load.
Best use cases
- 12V, 24V, 48V systems
- Charge controller estimates
- Efficiency support
- DC load planning with clear unit labels.
Common mistake to avoid
Do not use 12V battery voltage to size the solar panel input cable when the panel is actually operating near 18V, 30V, or 40V.
How to use the result
Read the amp result as a planning value, then add equipment-specific safety margin for heat, cable length, and controller limits.
Calculator output is a planning estimate. Final breaker sizing, wire gauge, derating, voltage-drop limits, equipment protection, and code compliance should be verified with manufacturer documentation and a qualified electrician or engineer.
For the broad formula, reference table, and breaker planning context, start with the main Amps to Watts Calculator.