Surge Watts

Definition

Surge (peak) watts are the short burst an inverter must supply to start an induction motor, compressor or pump. Running watts cover the continuous load (P = V × I). Many well pumps and RV air conditioners surge at about 5–7× running watts (LRA / FLA) unless a soft starter cuts that toward 2–3×. Size the inverter’s surge rating for the start, and the continuous rating for the run. Surge does not add extra daily watt-hours.

Calculators that use this

• inverters

  Inverter Sizing Calculator

  Size a pure sine inverter from continuous watts, motor surge and inverter efficiency with 25% headroom.

• appliances

  Off-Grid Well Pump Solar Sizer

  Size solar, battery and inverter surge for a well pump from running watts, LRA surge factor and daily pump hours.

• appliances

  RV Air Conditioner Solar Sizer

  Estimate daily watt-hours, battery amp-hours and solar array watts to run a rooftop RV air conditioner off-grid.