Solar Water Pump Sizing Calculator
Size DC solar submersible and surface water pumps for off-grid wells, livestock, and irrigation based on Total Dynamic Head (TDH), daily gallons, and solar PV array wattage.
Hydraulic Head & Solar Power Specifications
Solar Water Pump Sizing Calculator - Total Dynamic Head (TDH), GPM & PV Watts: Size DC solar submersible and surface water pumps for off-grid wells, livestock, and irrigation based on Total Dynamic Head (TDH), GPM, and solar array watts.
How to Use the Solar Water Pump Sizing Calculator - Total Dynamic Head (TDH), GPM & PV Watts
Input Daily Water Demand & Available Sun Hours
Specify daily volume in gallons or liters for cattle livestock, drip irrigation, or off-grid homesteads.
Enter Static Water Depth & Surface Elevation Rise
Input well depth to standing water and vertical lift from wellhead to the storage tank or cistern.
Configure Pipe Distance, Diameter & Pressure
Select pipe size (3/4" to 2" PVC) to calculate Hazen-Williams friction loss along long pipe runs.
Determine Total Dynamic Head (TDH) & PV Array Sizing
Review required pumping GPM flow rate, pump motor wattage, and recommended solar panel array rating.
Engineering Guide: Principles & Formula Details
Solar-powered DC water pumping represents the most cost-effective and reliable solution for livestock watering, off-grid homestead water supplies, and agricultural drip irrigation in remote rural areas. By eliminating expensive multi-mile utility grid extensions and noisy, maintenance-heavy diesel generator pumps, solar pumps provide clean pressurized water directly from solar photovoltaic irradiance.
Accurate pump sizing hinges upon calculating the Total Dynamic Head (TDH), which represents the total equivalent vertical feet of resistance the pump must overcome. TDH comprises four distinct components: (1) Static Water Depth from the wellhead down to the pumping water level; (2) Vertical Elevation from the wellhead up to the storage tank; (3) Friction Loss caused by turbulent drag inside the pipe; and (4) Pressure Head if pumping into a pressurized captive-air tank (where 1 PSI of pressure equals 2.31 feet of water head).
Selecting adequate discharge pipe diameter is critical. According to the Hazen-Williams hydraulic flow equation, pipe friction losses escalate exponentially as pipe diameter decreases or flow velocity rises. For example, pushing 10 GPM through 1,000 feet of 3/4" PVC pipe creates an enormous 78 feet of friction head loss, whereas upgrading to 1-1/4" pipe reduces friction loss to a negligible 6.2 feet. Upsizing pipe often allows installing a significantly smaller pump and fewer solar panels.
In off-grid solar pumping engineering, the best battery is water stored in a tank. Storing water in elevated poly holding tanks on hillsides or timber stands provides gravity-fed pressure to livestock troughs and homes day and night. This eliminates expensive lithium or lead-acid battery banks, allowing the solar array to drive the DC brushless pump directly via an MPPT solar pump controller with variable-frequency motor soft-starting.
Key Engineering Features & Advantages
Hazen-Williams Pipe Friction
Calculates dynamic pipe friction losses across 3/4" to 2" Schedule 40 PVC and PE lines.
Zero Battery Reliability
Sizes direct-drive solar pumping systems storing clean energy as gravity water in tanks.
Livestock & Homestead Sizing
Preconfigured for cattle ranching, sheep, drip orchards, and residential off-grid wells.
TDH & Pressure Conversion
Seamlessly converts PSI pressure tank backpressure into equivalent vertical hydraulic head.
MPPT Controller Headroom
Adds standard 30-35% solar irradiance headroom to ensure smooth morning motor startup.
Replaces Diesel Generators
Eliminates thousands of dollars in annual diesel fuel, oil filters, and remote generator trips.
Frequently Asked Questions
Total Dynamic Head is the total equivalent vertical height in feet that a pump must push water against. It is calculated as: TDH = Static Water Depth + Vertical Rise to Tank + Pipe Friction Loss + Pressure Head (PSI * 2.31).
Most standard off-grid DC solar submersible pumps (drawing 300W to 900W to pump 5 to 15 GPM from 150-foot wells) require between two and four 400W solar panels (800W to 1,600W array) wired in series to supply sufficient operating DC voltage.
Yes, but flow rate decreases. Variable-frequency solar pump controllers automatically throttle motor speed and GPM down when cloud cover reduces solar irradiance, maintaining pump rotation without stalling or overheating the brushless motor.
Storing water in an elevated storage tank costs far less than chemical batteries, requires zero maintenance, lasts 30+ years, and provides reliable pressurized water via gravity even during multi-day storms without battery degradation.