Solar Powered Single Phase 3-inch AC Pumps for Replacing Windmills

There are more than 1 million windmill pumps mostly in South America, Australia, and big portion of Southwest of United States. Although they represent recognizable landmarks, their water pumping operation is not always reliable for livestock, as operation strongly depends on the wind recourse, which is unpredictable.

When those windmills were installed they were the only way of livestock watering. However, solar energy combined with modern motor technologies is replacing those outdated windmills. Solar as a resource is more predictable, and newly developed brushless DC (BLDC) motors based on permanent magnets are more efficient for this application. However, although solar panels are becoming more affordable, the cost of such solar systems is not decreasing as expected. This is because of expensive low volume custom BLDC motors and very specific solar panels that works for these particular BLDC motor pumps.

Proposed solar water pumping system is based on traditional single phase three wire AC motor pumps that have been in use for decades. Simple and reliable solar VFD controller is developed to operate the 3 wire single phase pump without a need of control box with capacitor and relay, but having this “starting capacitor” functionality in software. Not having additional starting capacitor eliminates another failure point in the system, making it more robust. Because proposed solar pumping system is using traditional AC pump, it’s possible to use AC source (generator or utility grid) as a backup system.

The biggest advantage of solar power single phase pumping system is in utilizing two commodity products: existing off-the shelf three wire single phase pump and low cost solar panels. Providing customer with existing pump products they are familiar with sizing is a huge benefit, as they already have those single phase 3 wire units installed in the field.