Quick Answer
A well pump can be run on an off-grid solar system, but it requires careful design and sizing of the system to meet the pump's energy demands.
Choosing the Right Pump
When selecting a well pump for an off-grid solar system, consider the pump’s power rating in watts or horsepower. A common 2-horsepower (hp) well pump uses around 2.4 kilowatts (kW) of power, which is equivalent to 2,400 watts. The pump’s voltage and amperage requirements should also be matched to the solar panel array’s output.
Sizing the Solar Panel Array
To determine the required solar panel array size, calculate the daily energy demand of the pump. Assuming an 8-hour pumping cycle per day, the 2-hp well pump consumes around 19 kilowatt-hours (kWh) of energy per day. Using a solar panel efficiency of 20%, the required array size would be around 7.4 kilowatts (kW) or 28 solar panels with 260 watts each. This calculation assumes a peak sun hour (PSH) of 5 hours per day in the location.
System Design Considerations
The solar panel array should be designed to produce excess energy during peak sunlight hours to account for the pump’s varying energy demands. A battery bank with sufficient capacity is also required to store excess energy for nighttime or low-sun periods. The battery bank’s capacity should be sized to match the pump’s daily energy demand, taking into account the system’s efficiency losses and the battery’s depth of discharge.
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