Solar Deep-Well Submersible Water Pump Sizer
Size solar submersible water pumps for off-grid homesteads, livestock, and agriculture. Calculates Total Dynamic Head (TDH), pipe friction loss, daily gallons, and required solar array wattage.
Enter the values above and click Calculate to view recommendations and engineering specifications.
Direct Solar Pumping vs. Battery Storage
Calculation Assumptions
- Total Dynamic Head (TDH) = Static Vertical Lift + Dynamic Pipe Friction Loss + Pressure Head.
- Submersible DC pump motor efficiency estimated at 55%–65% from solar PV input.
Engineering Limitations
- Well recharge recovery rate must exceed pump GPM capacity to prevent dry running.
A 180-foot deep well pumping 6 GPM through 250 feet of 1" poly pipe creates 195 feet of TDH. Pumping for 5 Peak Sun Hours produces 1,800 gallons daily, requiring ~550W of solar PV array.
In off-grid water systems, the most reliable and cost-effective approach is **direct solar pumping** (water pumped directly into an elevated storage tank whenever the sun shines) rather than cycling water pumps off a chemical battery bank:
System Engineering Guidelines:
- Water in a Tank is Cheaper Than Batteries: A 2,500-gallon polyethylene water tank costs approximately $1,200 and lasts 25+ years with zero maintenance. Storing equivalent pumping energy in lithium batteries costs three times as much and wears out in 10 years.
- Helical Rotor vs. Centrifugal: For deep wells (over 100 ft lift), progressive cavity helical rotor pumps (such as Lorentz or Shurflo 9300) provide far higher efficiency at low solar wattage than multi-stage centrifugal impellers.
- MPPT Pump Controllers: Solar pump controllers convert variable solar panel voltage and current into optimal torque, allowing the pump to start in early morning low-light conditions without stalling.
Frequently Asked Questions
How do you calculate total dynamic head (TDH) for a well pump?
Total Dynamic Head (TDH) equals: Static Water Lift (vertical distance from pumping water level in the well to highest discharge point) + Pressure Head (system pressure converted to feet of head, where 1 PSI = 2.31 ft) + Friction Loss (pipe resistance in equivalent feet based on flow rate and pipe diameter).
What size solar array is needed for a 1/2 HP or 1 HP DC submersible pump?
A 1/2 HP DC pump consumes approximately 400W to 500W of electrical power; accounting for motor efficiency, pump controller losses, and solar panel derating, a solar array of 600W to 800W is recommended. A 1 HP pump consumes ~800W-1000W and requires 1,200W to 1,500W of solar panel capacity.
Do solar water pumps require a battery bank?
No. Many agricultural and livestock solar pumps operate as 'direct-drive' systems using a specialized MPPT pump controller without any batteries. The pump runs when sunlight is available, pumping water into elevated storage tanks or cisterns, which act as gravity 'batteries' for overnight use.
What is the function of a pump MPPT controller with linear current booster?
Early morning and late afternoon solar irradiance produces adequate panel voltage but low current, which is insufficient to overcome pump rotor inertia. A linear current booster controller down-converts panel voltage to boost amperage, allowing the motor to start pumping in low light conditions and extending daily pumping hours by 30%.