Solar PV Powered Standalone Water Pumping Systems: Modeling, Design, and Analysis

2. Background

The solar PV array directly converts the solar energy from the Sun rays into dc electric power. The generated dc power from the PV array is conditioned or transformed into the required form using Power Conditioning Unit (PCU). The PCU can be any inverter or converter circuit depending on the application of the PV system. With respect to the application, solar PV systems can be broadly divided into two categories: (i) Grid-connected PV system and (ii) Stand-alone PV system. In grid-connected PV systems, the solar PV power is fed into the grid in the form of high quality sinusoidal current using inverter. In contrast, in stand-alone PV systems, solar PV source with or without additional sources, maintains the defined voltage and current required by the stand-alone loads. Additional sources can be a battery bank, wind power, fuel cell, etc., and they are required due to the uncertainty in the PV power generation. However, stand-alone applications like solar water pump used in agriculture, multi-storey buildings or industries, etc., with water tank-storage may not require additional sources. Also, in such systems, PV source can always be operated near maximum power point (MPP), which gives the option of using generated PV power efficiently. Some good solutions presented in the literature for the PV fed water pump drive systems are briefed below.