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Solar Water Pumping

Solar Water Pumping offers a clean and reliable alternative to fuel-burning generators and windmills. Solar water pumps require no fuel and almost zero maintenance. Solar pumps are less expensive than windmills, are easier to install, and provide a more consistent supply of water.  This is especially true in areas where wind may be seasonal and inconsistent.  As many as 80% of our Western customers are replacing old high-maintenance windmills with reliable solar water pumping systems.  A solar pump produces its highest volume of water when water is needed the most - when the weather is sunny and hot! 

GenPro Energy Solutions specializes in providing and implementing the most efficient solar pump systems in the world. Our solar pumps can operate directly from photovoltaic (solar) panels or from batteries that are charged by any combination of DC input sources. Most of the Lorentz solar pump models we provide can be ordered with optional AC power inputs for situations in which utility power, inverter power or generator power is available but efficiency is necessary.

GenPro Energy's goal is to provide you with the most efficient, durable and economical solar pump solution available for your application.

The two types of solar pumps we provide are solar submersible pumps and solar surface pumps.  PV direct pumping is the most efficient method of powering these pumps.  However, in many situations where pumping is required 24/7 GenPro Energy will combine wind power hybrid systems for reliability and redundancy.

How is a pump powered by the Sun?

Sunlight in comprised of various wavelengths of light radiation, some of which are known as 'photons'. When light photons strike a solar module, a flow of electrons occurs in what is known as 'the photoelectric effect'.

When the electrons in the solar module are excited by the light, they follow the attached electrical circuit 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. The warming is caused by the exciting of electrons and directs them to flow in a path. This flow of electrons is by definition, electricity. Except unlike most surfaces, solar modules allow quick and efficient transmission of that energy.

By this process, photovoltaic (solar electric) cells convert sunlight directly into electricity. This electricity is collected by the wiring in the module, and supplied to the DC pump controller that operates the pump motor. At night, or in heavy cloud conditions, electrical production and pumping decreases (and eventually ceases) until sunlight returns.

Solar pumping systems work anywhere the sun shines. The majority of the continental US enjoys plenty of sun to operate a pumping system.

Where do solar pumping systems work?

Solar Water Pumping SystemThe 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 the 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.

The sunlight or insolation levels also vary seasonally. Fortunately, when water is needed most in the summer is when light intensity is greatest, whereas lower light intensity of spring and autumn produce less water, when less water is needed.

Small to medium solar-electric pumping systems are easily portable. By mounting the solar system on a trailer, a system can be moved from well to well in order to fill holding tanks. This is particularly effective for farmers for the rotation of grazing areas, so one solar array can be used for several well pumps.

Economics of Solar Water Pumping

The economy and reliability of solar electric power make it an excellent choice for remote water pumping. Cattle ranchers in the Western U.S., Canada, Mexico, and Australia are enthusiastic solar pump users. Their water sources are spread over many miles of rangeland where power lines are few and refueling and maintenance costs are substantial for generator use.

If your water source is 1/3 mile or more from the power line, solar is a favorable economic choice. This fact is reinforced by a number of Rural Electric Co-Operatives across the U.S.  These Co-Ops actively advocate the use of solar pumps, as the cost to extend new lines is subsidized by other rate payers.

A solar pump minimizes future costs and uncertainties. The fuel is free. Moving parts are reduced to as few as one. A few spare parts can assure you many years of reliable water supply at near-zero operating costs.

Mounting Structures and Array Placement

Solar modules should be located in a sunny spot where no shading occurs. Even shadows from a tree limb, tall grass, or fence rails can substantially reduce power output.

For these reasons we typically mount the solar modules on a pole or ground mount above any obstacles. Remember the solar array can be placed some distance from the water source if shading is a problem. Wire size can be increased to compensate for longer cable runs and the associated voltage drop.

Windmills: Yesterday's Answer to Remote Water Delivery

There are still thousands of windmill water pumping units standing in the western U.S. Regrettably, many are inoperable. These pumpers were very valuable for remote/off-grid sites, with the proper minimum wind conditions, and when manpower was plentiful and cheap. Windmills, though potentially long lasting, need dedicated maintenance. The down-hole leathers require regular 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 a windmill (or often less) the life time costs are much lower. Windmills must be used where there is a steady, constant wind for maximum results while solar pumps operate anywhere the sun shines. Similarly, where a windmill pumps water only when wind is adequate, solar pumping delivers more water when it is needed most - when the sun shines greatest. 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, which uses natural resources to deliver water in off-grid locations.

Fixed vs. Tracking Mount Structure

Fixed Mount structures are less expensive and tolerate higher wind loading. Fixed mounts are also lower-cost, but must either be adjusted in accordance to seasonal changes or use more solar modules to compensate for loss due to the sun's changing position in the sky.

On the other hand, tracking mount structures (a.k.a. solar trackers) keep the modules facing the sun all day long by automatically adjusing the angles throughout the day. This provides more power to the pump over a longer period, producing 20 to 40 percent more water daily in the summertime.

Trackers offer a great advantage when pumping water. Passive single axis trackers are known for their excellent reliability and service life. They take no power from the system as they operate from the heat of the sun striking the frame members, causing liquid-gas to move from one cylinder to another. Passive trackers come with extended warranties and are very reliable absent extreme wind conditions.

Active Trackers operate differently, using the sun's energy to mechanically adjust the array in the direction of the sun. Active trackers can be more accurate and may reposition themselves at night to prepare for the first morning sunlight.

Why we don't recommend batteries in water pumping systems

While batteries may seem like a good idea, they have a number of disadvantages in pumping systems. They reduce the efficiency of the overall system. The solar modules operating voltage is dictated by the battery bank and is reduced substantially from levels which are achieved by operating the pump directly. Batteries also require additional maintenance and under- and over-charge protection circuitry which adds to the cost and complexity of a given system. For these reasons, only about 5% of solar pumping systems employ a battery bank.

Gasoline Generators vs. Solar Energy

Generators are commonly used to provide power beyond the power line. There are several studies based on the economy of solar- versus generator-power. These studies consider all costs involved: modules, mounting structure, pumps, miscellaneous components, installation, operation, maintenance, yearly inspection, component replacement and salvage value. With this we can determine a life cycle cost and a present value. One such comparison was done by the Bureau of Land Management at Battle Mountain, Nevada specifically comparing solar water pumping systems. For one 3.8 GPM system with a 275 foot dynamic head (total lift), the PV system cost only 64% as much over 20 years as the generator system did over only 10 years. This remote solar site also used only 14% as many labor hours.

In 1989, Sandia National Laboratories noted that photovoltaic pumping systems in remote locations would often be cost effective compared to generators, even with 5 times the initial capital cost. Low end generators, which are initially expensive, require consistent maintenance and have a design life of approximately 1,500 hours. Small to medium sized solar pumping systems often initially cost less than a durable slow speed engine driven generator. Most larger pump systems initially cost more than generator systems, but tend to be far more economical in the end.