Solar-powered pumps use electricity made by solar panels or heat from collected sunlight instead of electricity from the power grid or diesel fuel. These pumps usually include solar panels, a charge controller, a water pump that runs on direct current (DC), a fuse box, electrical wires, and a water storage tank. Solar-powered pumps are more cost-effective because they have lower operating and repair costs and cause less harm to the environment compared to pumps that use engines powered by fuel. These pumps are helpful in areas where grid electricity is not available or not practical, and other energy sources like wind do not provide enough power.
Components
A PV solar-powered pump system has three main parts: one or more solar panels, a controller, and a pump. Solar panels make up most (up to 80%) of the system’s cost. The size of the PV system depends on the size of the pump, the amount of water needed, and the amount of sunlight available.
The controller has two main functions. First, it ensures the pump receives the correct amount of power from the solar panels. Second, it protects the system by turning it off if the voltage is too low or too high for the pump to operate safely. This helps the pump last longer and reduces the need for repairs. Other functions include automatically stopping the system when the water source is low or the storage tank is full, controlling water pressure, combining power from solar panels with an alternate source like the electrical grid or a generator, and allowing remote monitoring through an online portal provided by the manufacturer.
The voltage of the pump’s motor can be alternating current (AC) or direct current (DC). DC motors are used for small to medium systems up to about 4 kilowatts and are suitable for tasks like garden fountains, watering livestock, or small irrigation projects. DC systems are more efficient than similar-sized AC systems, which means smaller solar panels can be used.
If an AC solar pump is used, an inverter is needed to change the direct current (DC) power from the solar panels into alternating current (AC) for the pump. Inverters can handle power ranges from 0.15 to 55 kilowatts and are used for larger irrigation systems. However, the solar panels and inverters must be carefully sized to match the starting power needs of an AC motor. To help with this, manufacturers provide specialized software to calculate the system’s size. This software may include estimates of monthly water output, which can change based on seasonal differences in sunlight.
Water pumping
Solar-powered water pumps can provide drinking water, water for animals, or water for farming. These pumps are especially helpful for small farms or communities because large farms need a lot of water, which requires a very large solar panel system. If water is only needed part of the year, a large solar panel system might create extra energy that is not used, making the system less efficient unless the extra energy has another purpose.
In India, solar-powered water pumps are used for farming and drinking water. Many of these pumps use motors that require 2.0 to 3.7 kilowatts of power, which come from a 4.8 kilowatt photovoltaic (PV) solar panel system. A 3.7 kilowatt system can move about 124,000 liters of water each day from a depth of 50 meters and a height of 70 meters. By August 30, 2016, 120,000 solar-powered water pumping systems had been installed worldwide. Storing water is more efficient than using batteries for solar water pumps because no energy conversion is needed. Common pump types include centrifugal pumps, multistage pumps, borehole pumps, and helical pumps. Understanding scientific ideas like pressure, head, pump curves, system curves, and net suction head is important for designing and using solar-powered pumps effectively.
Oil and gas
To address concerns about the environmental effects of fossil fuels, including fracking, the oil and gas industry is using solar-powered pumping systems. Many oil and gas wells need precise chemical injections under pressure to keep operations running and increase oil or gas extraction. In the past, these pumps were powered by engines that used gas from the well, and the unused gas was released into the air. Solar-powered pumps can reduce harmful greenhouse gas emissions. Solar panels not only provide a clean energy source for these pumps but can also power remote monitoring systems. These systems allow operators to control and check equipment from faraway locations using satellite or cell phone communications, sending data to computers for monitoring.
Stirling engine
Sunlight can be focused on the heat exchanger of a Stirling engine to create heat, which is then used to operate a pump without needing electricity. This method avoids the need for solar panels and electrical equipment, reducing costs. In some situations, a Stirling engine can be built locally, making it easier to use without importing parts. A type of Stirling engine called the fluidyne engine uses the pumped fluid as a piston to function. Studies on fluidyne solar pumps began in 1987. At least one company has tested a Stirling engine powered by sunlight to operate a pump.