Submitted to: National Solar Conference
Publication Type: Proceedings
Publication Acceptance Date: 7/31/2005
Publication Date: 8/8/2005
Citation: Vick, B.D., Clark, R.N. 2005. Water pumping performance of a solar-PV powered helical pump. In: Proceedings of International Solar Energy Society (ISES) 2005 Solar Water Congress, August 8-12, 2005, Orlando, Florida. 2005 CDROM. Interpretive Summary: Farmers and ranchers in the U.S. operate on very thin profit margins, so they need a very economical and reliable water pumping system for watering their livestock at remote wells (e.g., no 120 Volt single-phase or 240 Volt 3-phase electrical utility lines near the well). For static water well depths in 164 to 246 foot range, a helical pump powered by 480 Watts of photo-voltaic (PV) panels could pump enough water to satisfy the water requirements of 115 to 150 cattle. For static water well depths in 246 to 328 foot range, a solar powered helical pump powered by a 640 Watt PV array could pump enough water to satisfy the water needs of 120 to 145 cattle. The solar-PV helical pump systems mentioned above assumed a solar resource typical of Bushland, TX (located 10 miles west of Amarillo in the Texas Panhandle). Also, the solar powered helical pumps began pumping water at low solar radiation levels which means significant amounts of water could be pumped on cloudy days. Since Bushland is in a semi-arid climate, pumping water on cloudy days is not a significant advantage, but this low solar radiation water pumping would be very desirable at cloudy locations. This research also showed that multi-crystalline silicon PV modules had a peak panel efficiency of 12.4% compared to a peak panel efficiency of only 3.9% for thin-film amorphous-silicon (a-Si) panels. Although the price per Watt (~$5/Watt) is about the same for the multi-crystalline silicon and the a-Si panels, the a-Si panels are no longer being manufactured. The total cost of the solar powered helical pump systems tested was between $4,000 and $5,000 which makes them affordable for most farmers and ranchers in the U.S. Therefore, for pumping depths in the 165 to 330 foot range, the solar powered helical pump is a better choice than the mechanical windmill or the solar powered centrifugal pump most of the time.
Technical Abstract: A solar-PV powered helical pump was tested at three different pumping depths (50, 75, and 100 meters) and two different solar-PV array power ratings (480 and 640 Watts). This testing began in February 2004 and has been performed continuously since that time at the USDA-ARS Laboratory near Bushland, TX. So far, this solar-PV water pumping system has performed very well and reliably and it should be a good economical system for many livestock watering applications. For all pumping depth/PV power ratings tested, a relatively high total system efficiency of 5 to 7% was achieved and a low cut-in irradiance of 100 to 300 W/m2 was demonstrated. For Bushland, TX (annual average of 5.5 to 6 kWh/m2/day at latitude inclination) the amount of beef cattle that could be watered ranged from 60 cattle (100 m pumping depth/480 W PV array) to 150 cattle (50 m pumping depth/640 W PV array).