Experimental investigation of solar powered diaphragm and helical pumps

For several years, many types of solar powered water pumping systems were evaluated, and in this paper, diaphragm and helical solar photovoltaic (PV) powered water pumping systems are discussed. Data were collected on diaphragm and helical pumps which were powered by different solar PV arrays at multiple pumping depths to determine the pumping performance, efficiency, and reliability of the different systems. The highest diaphragm pump hydraulic efficiency measured was ∼48%, and the highest helical pump hydraulic efficiency measured was ∼60%. The peak total system efficiency (e.g. solar radiation to pumped water) measured for the diaphragm and helical pumps were ∼5% and ∼7%, respectively (based on PV modules with ∼12% efficiency). The daily water volume of the three-chamber high head diaphragm pump performed better than the dual-chamber high head diaphragm pump (∼5 to ∼100% depending on PV array input power and pumping depth). Use of a controller was shown to improve the quad diaphragm pump performance below a solar irradiance of 600 W/m2 (20 m head) to 800 W/m2 (30 m head). While diaphragm pumps made mostly of plastic demonstrated similar to much better pumping performance than diaphragm pumps made with a high proportion of metal, the metal pumps demonstrated a longer service life (>2 years) than the plastic pumps service life (<2 years). Helical pumps analyzed in this paper were capable of deeper pumping depths and usually demonstrated a longer service life than the diaphragm pumps that were analyzed.