Areas receiving sunlight greater than 5 kW/m2, for at least 6 h/day, can harvest the solar energy for irrigation purposes. This enormous amount of solar energy can be tapped to lift water from the river. Solar power can be used with irrigation systems, such as solar pumps in basins where water needs to be lifted to a small height.
Solar pump runs on electricity generated by photovoltaic panels or the thermal energy available from collected sunlight as opposed to grid electricity or diesel run water pumps. The operation of solar powered pumps is more economical mainly due to the lower operation and maintenance costs and has less environmental impact than pumps powered by an internal combustion engine (ICE). Solar pumps are useful where grid electricity is unavailable and alternative sources (in particular wind) do not provide sufficient energy.
A solar pump system consists of a solar panel which is used to capture the suns' rays, a deep cycle leisure or marine battery to get extended running potential, 12V pump and tubing to carry the water from the reserve, through the system to the farm. A photovoltaic solar powered pump system has three parts: the pump, the controller and solar panel
The solar panels make up most (up to 80%) of the cost.The size of the PV-system is directly dependent on the size of the pump, the amount of water that is required (㎥/d) and the solar irradiance available.
The purpose of the controller is twofold. First, it matches the output power that the pump receives with the input power available from the solar panels. Second, the con-troller usually provides a low voltage protection, whereby the system is switched off, if the voltage is too low or too high for the operating voltage range of the pump. This increases the lifetime of the pump thus reducing the need for maintenance.
Solar water pumps are specially designed to utilise DC electric power from photovoltaic modules.
Solar pumps can be used for drawing water from canals, tube wells, open wells etc.
A surface solar pump is mounted at ground level and works well when they draw water from less than 10-20 feet depth.
A submersible pump is lowered into the water. Most deep wells use submersible pumps.
With more hours of peak sun, a smaller pump and power system can be used, thus reducing overall cost.
Electrical energy from the solar modules is stored in the batteries so that the pump can function in non-sunny times.
The solar panels need to be cleaned occasionally with water to remove accumulated dust. The panels should not be covered by trees or other structures that block the sunlight. Seek help from a professional if the pump is not functioning properly.
A treadle pump is a human-powered low-cost pump used for lifting water for irrigation. It is designed to lift water from a shallow depth (upto 7 metres). The pumping is done by operating treadles or foot pedals, which drive two pistons inside two cylinders, creating vacuum that draws water to the surface.
The pump head consists of a twin barrel connected by a junction box in one end.
A check valve is installed at the bottom of the cylinder, which ensures one way flow of water.
Two pedals are connected to the two pistons and attached to each other with a pulley and rope system.
A guide pole is placed at the front of the pump to prevent the two paddles from clashing. A handle is attached to this horizontally to provide support to the operator.
The pump is powered by shifting the weight from one pedal to the other, moving the pistons up and down, creating suction pressure. The suction pressure creates a vacuum in the cylinders and water is forced to enter the cylinders through an inlet pipe connected to the junction box.
This device is relatively easy to install and maintain. It should be installed by a trained technician.
Periodic repair or replacement of the treadle frame is required. Extra pairs of washers, check valve, and bamboo treadle frame can be kept on hand for repair.
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