Can a 100-watt solar panel power a submersible well pump?

Submersible Pump Wattage and Solar Panel Sizing

A typical submersible well pump draws anywhere from 400 to 2,000 watts, depending on its size and the well’s depth. To power such a pump, you’d need a significantly larger solar panel array. For example, a 2,000-watt pump would require a solar panel array of at least 4-6 kilowatts to provide enough energy during the day. This is assuming an efficiency of 20% and an average daily solar irradiance of 5 hours.

Direct Drive, Battery, and VFD Considerations

One possible approach is to use a direct drive system, where the solar panel is connected directly to the pump. However, this method is often less efficient and may not be the best option for larger pumps. A more common setup involves using a battery bank to store excess energy generated by the solar panels during the day. This stored energy can then be used to power the pump during periods of low sunlight or at night. Another option is to use a Variable Frequency Drive (VFD) to control the pump’s speed and reduce energy consumption. A VFD can help optimize energy usage and reduce the required solar panel size.

Calculating Required Solar Panel Size

To calculate the required solar panel size, you can use the following formula:

Required solar panel size (kW) = Pump wattage (W) x Daily hours of operation / (Daily solar irradiance (kWh/m²/day) x System efficiency (%))

Assuming a daily solar irradiance of 5 hours and a system efficiency of 20%, the required solar panel size for a 2,000-watt pump would be:

Required solar panel size = 2,000 W x 8 hours / (5 kWh/m²/day x 0.20) ≈ 6400 W or 6.4 kW

A 100-watt solar panel would be grossly inadequate to power even the smallest submersible well pumps.