Effective Utilization of Solar Power for Isolated Water Pumping System

Abstract

The imbalance between energy demand and the power generation has the world to look for alternative solution called Renewable energy sources. Amongst the available energy sources, Photovoltaics (PV) has gained a lot of prominence in the present days due to its reliability and less maintenance. Therefore, the applications of PV have also become multitudiouos ranging from street lights, roof top lighting till satellites.However the major drawback are its high initial costs and low energy conversion efficiency. Therefore, one of the major focus of research lie in development of efficient power electronic converters and controllers.Due to the abundance of solar energy, and adequate requirement of water,research focus has been more on development of PV fed water pumping systems. Over the years of developments in the field of PV pump systems and power electronics technology, several topologies and control strategies have been developed. However, all these studies mentioned above assumes the PV to be receiving uniform irradiance. In an array consisting of a number of panels, it is very much sure that not all panels receive same irradiation. Often some panels are exposed to shades of buildings,clouds, etc., causing multiple peaks in the characteristics of PV array,and is termed as partial shading condition (PSC). Extracting maximum power (MPP) under such conditions becomes more challenging and complex. The non linear behavior of PV, power electronic converters and the load makes the analysis even more difficult. This study on the impact of PSC in PV systems is of high importance especially in the field of water pumping systems because PV fed water pumps are often employed in agricultural sectors where panels are exposed to soiling, shades of trees and clouds. In case of uniform shading, the MPP for varying irradiance occursnear the open circuit voltage region of the PV characteristics. In case of partial shading, the MPP occurs anywhere from short circuit current to open circuit voltage regions.