Size the pump: flow, total dynamic head and solar array
The pump must lift enough water, high enough, in the hours the sun shines. Getting head and flow right avoids an underpowered or wasteful pump.
How
- Set the pumping rate. Virginia Tech gives design flow as daily need divided by (peak sun hours times 60), in volume per minute. Never exceed the well's sustained yield (Colorado State).
- Work out total dynamic head (TDH). Colorado State adds depth to static water level, drawdown at the pumping rate and the height from wellhead to tank top, then multiplies by 1.1 for friction. Add any pressure needed at delivery.
- Estimate hydraulic power: water horsepower equals US gpm times head in feet divided by 3,960 (in metric, about 0.163 W per L/min per metre). Divide by pump efficiency from the maker's curve for input power.
- Size a preliminary PV array at about 1.25 times pump wattage, as Colorado State and Virginia Tech advise, then confirm with the power module.
- Prefer submersible pumps for wells. Colorado State notes surface pumps lift only about 3 to 6 m (10 to 20 ft) and are more exposed to freezing.
- Prefer water storage over batteries. Colorado State says batteries are unnecessary if storage is adequate.
Safety: Isolate power before working on any pump. Pump cables in wet wells can be lethal.
Do these first
Sources
- Solar-Powered Groundwater Pumping Systems. Colorado State University Extension, accessed 2026-11
- BSE-346: Solar water pumping for livestock (design steps). Virginia Cooperative Extension, Virginia Tech, accessed 2026-11
- 8.06: Power Requirements (Irrigation Systems Management). LibreTexts Workforce, accessed 2026-11