Solar energy is a natural and symbiotic alternative to pumped hydro. It is one of the most economically attractive solar applications, and direct-drive photovoltaic systems typically provide decades of reliable service. There is a good match between seasonal solar resources and seasonal water demand. Photovoltaic water pumping (PVWP) systems can meet a wide range of needs and are relatively simple, reliable, cost-competitive and low-maintenance. A typical system configuration includes a PV array, pump, controller, inverter (for AC), and overcurrent protection. Until recently, PVWP systems have only been competitive for relatively small pumping loads. Over the past decade, the competitiveness of PVWP has increased dramatically, greatly expanding the range of pumping loads/requirements for which PVWP is competitive.
The price of PV modules has fallen dramatically over the last decade, by over 80%, while the price of competitive gasoline or diesel has increased by over 250%. For steady pumping needs, such as community water supply or livestock watering, PVWP is the most cost-effective - in most cases for year-round pumping needs, and for irrigation water when irrigation is going on for most of the year. New technological innovations in controller technology have expanded the range of PVWP by an order of magnitude to 25 kW, with an expectation of 100 kW in the near future. Likewise, more efficient spiral rotor pumps have been developed that are reliable and simple to operate.
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