How does the sun power a pump?

The photovoltaic effect produces a flow of electrons. Electrons are excited by particles of light and find the attached electrical circuit the easiest path to travel from one side of the solar cell to the other. Envision a piece of metal such as the side panel of a car. As it sits in the sun, the metal warms.

This warming is caused by the excitation of electrons, bouncing back and forth, creating friction, and therefore, heat. The solar cell merely takes a percentage of these electrons and directs them to flow in a path. This flow of electrons is, by definition, electricity. Photovoltaics or solar electric cells convert sunlight directly into electricity. This electricity is collected by the wiring in the module, then supplied to the DC pump controller and motor, which, in turn, pumps water when-ever the sun shines.

Where do solar pumping systems work?

Solar pumping systems work anywhere the sun shines.

The intensity of light varies greatly throughout the day. Morning and afternoon sunlight is less intense because it is entering the earth''s atmosphere at a high angle and passing through a greater cross section of atmosphere, which reflects and absorbs a portion of the light.

We measure sun intensity in equivalent full sun hours. One hour of full sun is roughly equivalent to the sunlight on a clear summer day at noon.

These light or insulation levels also vary seasonally. Fortunately, most needs for water correspond with the sunniest seasons of the year - spring, summer and fall. One of the advantages of providing additional sources of water for livestock use is increased forage utilization. On large tracts some areas are not fully utilized because they are too far from water. As you know, livestock will only travel so far between feed and water.

Small to medium solar electric pumping systems are easily portable. By mounting the solar system on an axle or trailer, a system can be moved from well to well. This increases the economic return of a system by increasing the seasons of use. It may also correspond with the rotation of grazing areas.


Solar vs. Windmills


Windmills, though potentially long lasting, need dedicated maintenance. The downhole leathers require inspection and high winds can cause mechanical damage to the blades. Parts for these mills are expensive and sometimes hard to find.

Solar water pumping systems have many advantages over windmill water pumpers. Though the initial cost of solar powered systems can be similar to that of windmills (however, in many cases far less!), the lifetime costs are much lower. Windmills must be used where there is a steady, constant wind for maximum results while solar powered pumps operate anywhere the sun shines. Solar pumping systems can be installed in less than a day by an individual or small crew and can be portable, while windmills (because of the need to erect a tower) can take a larger crew a much longer time to install. Windmills are secured to the ground and are stationary. Solar powered water pumping systems are the modern day, upgraded version of the windmill - using natural resources to deliver water in off grid locations.


Determining height from source to storage area

If you have or can borrow a transit, this will be easier. If not, just use a line level. Start at your water source and look along the plane of the level to a landmark (a rock, stick, another person). Walk to the landmark and repeat the process. Count how many times you did this and multiply it by the distance from the ground to your eye. This will give you the "total head" you need to pump. Another way (in cases of great lifts) is to walk the distance carrying an altimeter. If a water line is already in place, you can tell by measuring the pressure at the bottom of the pipe when it is full of water. The basic formula is 2.31 psi = vertical feet. Since you know the head, just divide by 2.31 for a psi (pounds per square inch) figure. In reverse, if you already have a water pipe installed, you can use a pressure gauge at the bottom to find your head - just multiply the psi reading times 2.31 to get vertical feet.


How are solar pumps installed?


Installation is nuts and bolts assembly, basic plumbing, and simple wiring. No special equipment is needed to lower the pump by hand. Instructions are very thorough. We have shipped hundreds of solar submersibles to pump dealers, ranchers and homeowners. Sometimes they call us to ask a question or two, and sometimes they only call to order more!


Why isn`t solar pumping more popular?


It's a new technology, with challenges of its own. The nature of variable electricity in the form of direct current (DC) is quite different from conventional, steady alternating (AC) current. Using it economically dictates utilizing the long solar day, drawing a minimum of power. This means pumping slower than conventional pumps. Pumping at rates of less than 6 GPM requires different mechanisms from the conventional (centrifugal), unless we have power (money) to burn. Small solar pumps are unique, both electrically, and mechanically. The environment of a water well is unforgiving. Any imperfection will cause a failure. Since photovoltaics (PV) hit the market in 1980, we have seen many successes and many failures in solar pumping. Solar pumps have been difficult to market, too. Until recently, there existed a great gap in the range of available products.