Understanding your water pump's real load
The direct answer for a typical household
A 750-watt pump running 20-second cycles, 15 times a day for moderate household use, adds about 62Wh to the daily load. This is far less than a flat 30-minute-a-day estimate might suggest, since real pump runtime is measured in seconds per cycle, not minutes, and the pump spends most of the day sitting idle between cycles. Current figures live on the EPA's guide to protecting a private well, which updates them when the program changes. Panels are only half an off-grid system. The battery storage size calculator in our Battery & Storage section sizes the battery bank your daily load needs to get through cloudy stretches.
Why cycle-based math beats a flat hours estimate
A pressure tank pump runs in short bursts, typically 15 to 30 seconds at a time, to refill the tank whenever water use drops pressure below a set point. Estimating pump runtime as a flat block of minutes or hours a day, a common shortcut in general load calculators, tends to overstate actual power draw significantly, since the pump is idle far more of the day than it actually runs. The annual maintenance cost estimator turns this result into a concrete next step.
How cycle count scales with household usage
Light occasional use by 1 to 2 people commonly runs around 8 cycles a day, moderate daily use by 2 to 4 people runs around 15 cycles, and heavy use in a larger household with more frequent showers, laundry, and dishwashing can run 25 cycles or more. Actual cycle count depends heavily on household size, water habits, and pressure tank size, so use your own observed cycle count if you can time it directly.
Startup surge doesn't change the daily load math much
Well pumps commonly surge to several times their running wattage for a brief moment at motor startup, which matters a great deal for sizing an inverter's surge capacity but has minimal effect on total daily watt-hours, since the surge only lasts a fraction of a second within each cycle. Use running wattage for this calculation, and check the inverter sizing calculator separately to confirm your inverter can handle the surge, or the inverter sizing for well pump startup in our inverters and equipment tools for a version built specifically around this exact surge problem.
What to do with your pump load figure
Add the pump's daily energy to the same total load list as your other appliances instead of relying on a generic flat estimate, which likely overstates what your pump actually contributes. Regional groundwater data from USGS's water resources program is a useful reference if you're also trying to understand your well's likely output, and EPA's guide to protecting a private well covers the maintenance side of keeping the whole well system reliable. The annual maintenance cost estimator in our maintenance and lifespan tools rounds out the ongoing cost picture beyond just the electrical load.