Title: Determining the optimum solar water pumping system for domestic use, livestock water, or irrigation Authors
Submitted to: National Solar Conference
Publication Type: Proceedings
Publication Acceptance Date: March 30, 2009
Publication Date: July 1, 2009
Citation: Vick, B.D., Clark, R.N. 2009. Determining the optimum solar water pumping system for domestic use, livestock water, or irrigation. In: Proceedings of the 38th American Solar Energy Society Annual Conference, May 11-16, 2009, Buffalo, New York. 2009 CDROM. Interpretive Summary: In many instances, using solar energy is the best and most economical way of pumping water from streams, rivers, or wells for off-the-grid applications (farm/ranch houses, mountain cabins, livestock watering, and irrigating gardens/orchards/crops). However, the consumer is usually confused by all the choices that are involved in the selection of a stand-alone water pumping system. This paper discusses the advantages and disadvantages of the different water pumping options available and should educate the consumer and/or the installer on the selection of the best water pumping system no matter how large or small the water requirements. The paper addresses the issue of whether to choose a wind or solar powered water pumping system. If a solar powered system is selected then the next step is to choose between the types of solar photovoltaic (PV) modules needed for generating electricity from the sun to power the pump. A comparison is shown on how higher voltage PV modules will improve the pumping performance for helical pumps. One of the most confusing aspects of selecting a solar-PV water pumping system is in the selection of the type of pump (diaphragm, helical, piston, or centrifugal), and a graph in the paper depicts which pump is best for different pumping depth and daily water volume requirements. There is also a discussion on the types of controllers required for the different pump types. For a diaphragm pump, a comparison is made between using a controller and not using one. For a helical pump, it is demonstrated on how improvements in one helical pump manufacturer's controller substantially improved the pumping performance. For a centrifugal pump, the improvement in using a 3-phase instead of a single phase AC motor is shown. Since several wind and solar water pumping systems have been tested at the USDA-Agricultural Research Service, Conservation and Production Research Laboratory (located near Bushland, Texas in the Texas Panhandle) since the 1970's, we also discuss lessons learned on what is required to achieve a reliable, economical, low maintenance renewable energy powered water pumping system. Three case studies for different applications are shown to demonstrate the sizing of a solar water pumping system (solar PV module array size, type pump that would be best, and pump motor rating). This paper will be beneficial for users and installers of remote stand-alone water pumping systems, but will also be of benefit to manufacturers to see where there are currently no reliable and economical solar, wind, or hybrid systems available (e.g. mainly those applications requiring large water requirements like for crops, orchards, town water supplies, etc. at pumping depths greater than 30 ft).
Technical Abstract: For several years we have field tested many different types of solar powered water pumping systems. In this paper, several steps are given to select a solar-PV water pumping system. The steps for selection of stand-alone water pumping system were: deciding whether a wind or solar water pumping system would be best; determining the type of PV module; how controller can affect the decision; selecting pump type (diaphragm, piston, helical, or centrifugal); and analyzing the monthly water demand requirement. Three case studies are also included to demonstrate how to determine PV array size, motor/pump rated power, and type of pump.