Storing energy for getting water beyond the solar day:
In circumstances where energy has to be stored, batteries are expensive and might need high maintenance. While battery technology has evolved rapidly in recent times [e.g. Ion-lithium or salt water batteries] and they come with lower maintenance and longer lifespans, they come with other challenges related to higher costs, work temperatures, lack of expertise or low to inexistent documented experience in humanitarian and rural settings. Pumping water to elevated water tanks is a way to store energy that is preferable but tanks might need to be oversized when Solar is the only power source. Hybridization of systems (solar+ diesel generators) is another solution typically encountered in off-grid areas where stand-alone solar systems cannot meet the water requirements.
Wind power for water pumping applications:
Wind power technology for water pumping is being increasingly discarded especially due to the necessary skilled regular maintenance and parts replacement required. Except for very specific locations, solar PV stand-alone (or coupled with grid or diesel generator) offer a much more reliable solution.