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Generator Size Formula:
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Generator size calculation determines the appropriate power output (in kW) needed from a generator to meet your energy requirements based on your total energy consumption (kWh), operating time, and generator efficiency.
The calculator uses the generator size formula:
Where:
Explanation: The formula converts your total energy needs into the required continuous power output, accounting for how long you'll be running the generator and its efficiency.
Details: Correct generator sizing ensures reliable power supply, prevents overloading, improves fuel efficiency, and extends equipment life. Undersized generators may fail to meet demand, while oversized ones operate inefficiently.
Tips: Enter your total energy needs in kWh, expected operating time in hours, and generator efficiency (default is 0.8 for typical diesel generators). All values must be positive numbers.
Q1: What's a typical efficiency value for generators?
A: Diesel generators typically have 70-85% efficiency (0.7-0.85), while natural gas generators might be slightly lower at 65-75%.
Q2: Should I add a safety margin to the calculated size?
A: Yes, it's common practice to add 10-25% to the calculated size to account for startup surges and future expansion.
Q3: How do I determine my total kWh needs?
A: Sum the wattage of all devices you'll power, multiply by hours of use, then divide by 1000 to get kWh. Or check your electric bills for historical usage.
Q4: Does this calculation work for solar generators?
A: The principle is similar, but solar systems require additional considerations like battery storage and solar input.
Q5: What about three-phase vs single-phase generators?
A: This calculator gives kW size. For three-phase, you'll need to consider voltage and power factor for proper selection.