Solar pumps are specifically designed to accept DC power directly from the solar modules and are optimized for operating under less-than-ideal sun conditions. Where conventional AC-powered pumps require a stable voltage and frequency to operate, solar pumps can operate over a wide range of voltage and available current.

Conventional AC-powered pumps require large amounts of power to move large volumes of water in a short period of time. Solar pumps typically move a smaller volume of water over an extended period of time. This method requires far less power, which minimizes the size and cost of the PV array.

There are several methods for pumping water in remote areas, such as windmills, gas/diesel pumps, and ram pumps. But most of these options are either too expensive to install, or for fuel and maintenance, or require specific site conditions to operate.

Solar pumps can work for most locations and are at full capacity when needed most: during warm, sunny days. In temperate regions, they can be used year-round—which can be particularly helpful for potable water, animal grazing, and other farming operations. For many sites, a solar pump is often the best option for reducing cost and labor…

Useful article giving solid indrodution to solar water pumoping techmologies. Read more here:
Solar-Powered Water Pumping | Home Power Magazine.