Quantity multiplied by rated wattage gives connected load.
How this calculator works
A load calculation should not assume that every nameplate watt is drawn all day. We separate connected watts, simultaneous running load, startup surge and daily energy so that the result is useful for inverter, battery and solar sizing.
Simultaneity factors estimate the load likely to operate at the same time.
Hours per day and duty cycle convert power into daily energy in kWh.
Worked example
A practical planning scenario
Twenty 12 W LED bulbs add 240 W to connected load. If they operate for seven hours, they use about 1.68 kWh/day. A refrigerator may have a lower wattage but runs throughout the day on a cycling duty.
Frequently asked questions
What is the difference between kW and kWh?+
kW measures power at a moment; kWh measures energy used over time. Inverters are mainly sized in kW while batteries and daily usage are discussed in kWh.
Should I enter maximum appliance wattage?+
Use the manufacturer nameplate or measured running wattage when available. Typical defaults are only a starting point.
Why is surge load higher?+
Compressors and motors in air conditioners, refrigerators and pumps can briefly draw more power when starting.