Although photovoltaic (PV) Energy is a viable solution and clean energy source, it is an intermittent source and certainly needs energy storage, particularly in the case of off-grid applications. Batteries are normally used as the common energy storage, despite all their demerits.
This paper presents a preliminary design and cost estimate of a potential candidate for energy storage applications, which is the PV-based Pumped-Hydro Energy Storage (PHES). The proposal is suited for application in rural and distant areas, where the public electric grid is not easily accessible.
The basic idea is that the required load demand is fulfilled by PV panels during the day. During the periods of high insolation, the PV panels are also used to pump water to a 31-m height tank. Then, at night or in periods of low insolation the water is allowed to flow downwards operating a hydro generator.
Based on the average expected load (irrigation and domestic) of distant locations in Egypt, the PV panels and reversible pumps have been sized together with other system components. A cost estimate has been done to compare batteries and PHES for the average lifetime of the two systems.
The cost estimate revealed that the PHES would be economically viable after 23 years of service. The system can be easy to extend to a larger scale by adding more reversible pumps and PV panels.