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Solar-Powered Groundwater Pumping Basics

Solar-powered groundwater pumping systems are often considered for use in livestock and other remote watering applications instead of other forms of alternative energy because they are durable, can be mobile, and exhibit long-term economic benefits. Generally, alternative power is considered most feasible when the cost of tapping into the closest public power grid outweighs the costs of using alternative power. There are several technology alternatives for supplying power, or lift, to groundwater systems including: wind turbines, windmills, generators, and solar arrays. The driving factors for selecting the appropriate technology are regional feasibility, water demand, system efficiencies, and initial and long-term costs. Other factors often include the need for power and water reserves in the form of batteries and livestock tanks.

The selection of solar-powered pumping systems (SPPS) should only follow a thorough look at the feasibility and future prospect of the technology. There are several important steps in this process. The first step is to rule out other sources of power or pumping devices. If the public power grid is reliable and in proximity to the site, preferably less than 1/3 mile, then solar power may be a poor choice. The initial cost of implementing a SPPS can be more than the expense of connecting to the local power grid.

The average daily water consumption for a cow/calf pair in Colorado during the summer is approximately 20 gallons per day. A typical solar-powered system might serve 50 cow/calf pairs. This is a total of 1,000 gallons needed per day.

Site Location Considerations

The site location plays a major part in the feasibility of a SPPS. Peak sunlight hours (PSH) differ slightly across Colorado. The general rule is that the less PSH available, the more expensive the required photovoltaic (PV) array and pump. System costs increase when more storage is needed to compensate for the limited exposure of the PV array to peak sunlight hours. Most of Colorado has a PSH of between 5.0 and 6.0. Another factor is the climate of the region. Solar powered systems are not typically designed for extremely cold weather (temperature less than minus 20 degrees C or minus 4 degrees F). However, the systems can be insulated to handle colder temperatures.

Another important aspect to consider is security. The PV array should be protected from theft, vandalism, and livestock. It is strongly recommended that provisions be made to put a small fence around the array. The fence needs to have enough set-back that it does not cast a shadow on the array.

Lifetime and Operations

The long-term costs and ability of the SPPS to adapt to changing demands should be implemented into the feasibility of the system. Photovoltaic modules should last 20 to 25 years. This depends on it being maintained (kept clean and securely mounted) and protected from strong winds, lightning and hail storms, and falling objects such as tree branches. The solar pumps should last about 10 years. The other electronics and controls should be designed to last at least 10 years with little electrical maintenance. The overall lifetime of the complete system should be designed and maintained to last 25 years taking into account future demands of the livestock tank. Inspect the system at least once per week checking the pumping rate, operation of controller, condition of PV modules, tanks, wires, and pipes (for leaks/corrosion).

Last updated: October 18, 2017 at 11:59 am