Step 1: Define electric power.
Electric power is the rate at which electrical energy is consumed or converted.
Step 2: Recall SI units.
The SI unit of power is the watt (W).
Step 3: Compare with other units.
Joule is the unit of energy.
Volt is the unit of electric potential difference.
Ampere is the unit of electric current.
Step 4: Conclusion.
Therefore, the SI unit of electric power is Watt.