Quick Answer
To calculate power needs for a submersible well pump, determine the pump's flow rate and head, multiply by 1.5 to account for efficiency, and then consult a pump sizing chart or use an online calculator.
Understanding Pump Specifications
When sizing a submersible well pump, it’s essential to understand the flow rate and head requirements. The flow rate is typically measured in gallons per minute (GPM) or liters per minute (LPM), while the head is measured in feet (ft) or meters (m). A general rule of thumb is to multiply the pump flow rate by 1.5 to account for pump efficiency losses. For example, a 10 GPM pump would have a calculated power requirement of 15 GPM when accounting for efficiency.
Calculating Power Needs
To calculate the power needs for a submersible well pump, consult a pump sizing chart or use an online calculator that takes into account the pump’s flow rate, head, and efficiency. A common approach is to use the following formula: Power (Watts) = (Flow Rate x Head) / Efficiency. For a 10 GPM pump with a 100 ft head and 50% efficiency, the calculated power requirement would be: Power (Watts) = (15 GPM x 100 ft) / 0.5 = 3000 Watts.
Sizing Solar Systems and Batteries
When sizing a solar system to power a submersible well pump, consider the calculated power requirement, as well as system losses such as wiring, inverter efficiency, and battery discharge characteristics. A general rule of thumb is to oversize the solar array by 20-30% to account for these losses. For a 3000 Watt pump, a 3600-4200 Watt solar array might be required. Additionally, a deep cycle battery bank with a minimum capacity of 2-3 times the daily energy usage should be sized to provide backup power during periods of low sunlight.
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