The use of solar photovoltaics (PV) technology as an alternative to traditional energy sources such as petrol and diesel generators to power electric water pumps has become increasingly apparent. Solar PV technology is used extensively by remote villages and farmers as the power source to pump water for domestic consumption, sanitation, livestock and irrigation.

A variable speed drive (VSD) is a piece of equipment designed to regulate the speed and rotational force (torque) of an electric motor. VSD’s are becoming a standard inclusion as part of the solar water pumping system controller. This document explains is the role of VSD in solar pumping.