Trakia Journal of Sciences, Vol. 3, No. 7, pp 7-11, 2005
Copyright © 2005 Trakia University
Available online at:
http://www.uni-sz.bg
ISSN 1312-1723
SOLAR POWERED WATER PUMPING SYSTEMS
B. Eker*
Trakya University, Tekirdağ Agriculture Faculty, Agricultural Machinery
Department,Tekirdağ,Turkey
ABSTRACT
Agricultural technology is changing rapidly. Farm machinery, farm building and production facilities are constantly being improved. Agricultural applications suitable for photovoltaic (PV) solutions are numerous. These applications are a mix of individual installations and systems installed by utility companies when they have found that a PV solution is the best solution for remote agricultural need such as water pumping for crops or livestock. A solar powered water pumping system is made up of two basic components. These are PV panels and pumps. The smallest element of a PV panel is the solar cell. Each solar cell has two or more specially prepared layers of semiconductor material that produce direct current (DC) electricity when exposed to light. This DC current is collected by the wiring in the panel. It is then supplied either to a DC pump, which in turn pumps water whenever the sun shines ,or stored in batteries for later use by the pump. The aim of this article is to explain how solar powered water pumping system works and what the differences with the other energy sources are.
Key words: Agriculture, water, solar cell, pump
INTRODUCTION
It is common to use diesel to power generators in agricultural operations. While these systems can provide power where needed there are some significant drawbacks,
including:
• Fuel has to be transported to the generator’s location, which may be quite a distance over some challenging roads and landscape.
• Their noise and fumes can disturb livestock.
• Fuel costs add up, and spills can contaminate the land.
• Generators require a significant amount of maintenance and, like all mechanical systems, they break down and need replacement parts that are not always available.
There are also major disadvantages in using propane or bottled gas to heat water for pen cleaning or in crop processing applications, or to heat air for crop drying, including transportation to the location where you need the heat, costs of fuel and safety issues For many agricultural needs, the alternative is solar energy.These are systems that have been tested and proven around the world to be cost-effective and reliable, and they are already raising levels of agricultural productivity worldwide. (Figure 1)
In general, there are two types of solar systems – those that convert solar energy to D.C. power and those that convert solar energy to heat. Both types have many applications in agricultural settings, making life easier and helping to increase the operation’s productivity. energy to heat. Both types have many applications in agricultural settings, making life easier and helping to increase the operation’s productivity.
The solar cells in a PV module are made from semiconductor materials. When light energy strikes the cell, electrons are knocked loose from the material’s atoms. Electrical conductors attached to the positive and negative sides of the material allow the electrons to be captured in the form of a D.C. current. This electricity can then be used to power a load, such as a water pump, or it can be stored in a battery.[2]
It’s a simple fact that PV modules produce electricity only when the sun is shining, so some form of energy storage is necessary to operate systems at night. You can store the energy as water by pumping it into a tank while the sun is shining and distributing it by gravity when it’s needed after dark. For electrical applications at night, you will need a battery to store the energy generated during the day.(Figure 2).
Photovoltaic is a well-established, proven technology with a substantial international industry network. And PV is increasingly more cost-effective compared with either extending the electrical grid or using generators in remote locations. The cost per peak watt of today’s PV power is about $7. Local supply conditions, including shipping costs and import duties, vary and may add to the cost.
PV systems are very economical in providing electricity at remote locations on farms, ranches, orchards and other agricultural operations. A “remote” location can be as little as 15 meters from an existing power source. PV systems can be much cheaper than installing power lines and step-down transformers in applications such as electric fencing, area or building lighting, and water pumping –either for livestock watering or crop irrigation.
WATER PUMPING
Water pumping is one of the simplest and most appropriate uses for photovoltaic. From crop irrigation to stock watering to domestic uses, photovoltaic-powered pumping systems meet a broad range of water needs. Most of these systems have the added advantage of storing water for use when the sun is not shining, eliminating the need for batteries, enhancing simplicity and reducing overall system costs. Many people considering installing a solar water pumping system are put off by the expense. Viewing the expense over a period of 10 years, however, gives a better idea of the actual cost. By comparing installation costs (including labour), fuel costs, and maintenance costs over 10 years, you may find that solar is an economical choice. A solar-powered pumping system is generally in the same price range as a new windmill but tends to be more reliable and require less maintenance. A solar-powered pumping system generally costs more initially than a gas, diesel, or propane-powered generator but again requires far less maintenance and labour [4]. The cost per gallon of water pumped ranged from $0.002 to $0.007 per gallon.
Solar-Powered Water Pumping System Configurations
There are two basic types of solar-powered water pumping systems, battery-coupled and direct-coupled. A variety of factors must be considered in determining the optimum system for a particular application [1].
To be continue.................
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