Battery energy storage for variable speed photovoltaic water pumping system

The photovoltaic (PV) solar electricity is no longer doubtful in its effectiveness in the process of rural communities’ livelihood transformation with solar water pumping system being regarded as the most important PV application. To overcome the intermittent and uncertain nature of solar power output, the highly fluctuating load demands and to supply loads at night time, a battery storage system is optimally sized, designed and implemented. The bi-directional Buck-Boost converter use and control are essential for energy management between the batteries and the pumping system. Domestic loads power calculation is also demonstrated and varied. Additionally, various inverter control schemes are examined and employed depending on the nature of the load connected. Finally, simulation results using Matlab/Simulink are presented for two cases: when the battery system is connected with the PV array to feed the pump motor to achieve the required varying hydraulic performance (flow rate and pumping head) under different weather conditions, and when the battery system feeds the loads while the PV array is disconnected at night.