While it is not uncommon for farmers and ranchers to have their animals drink from creeks, ponds or other surface water sources, many are turning to alternatives to providing drinking water for livestock. The easy-to-install solar water pump is a very reliable way to pump water from the well to the ground storage tank, or from the surface to the high altitude. Some government agencies even provide cash grants to farmers and ranchers if they agree to graze from nearby creeks and streams and install alternative water supplies, such as wells using solar pumping methods.
Solar pump system components
The most basic forms of solar pumps include small direct current (DC) solar pumps, pump controllers, one or more solar modules, replacement well caps, wires and polyvinyl chloride (PVC) pipes. Anyone who can use a screwdriver and a pipe wrench should be able to assemble a solar pump kit. These systems are very basic. They do not require a power inverter or battery, and it is safer to use a 12 volt or 24 volt DC power supply than to connect a 240 volt alternating current (AC) pump to the grid.
Solar pump. Systems that require only a few gallons of water per minute from wells less than 100 feet deep typically require only a small DC submersible pump of 12 or 24 volts. Deeper wells or settings that require higher flow rates may require submersible pumps in the 48 to 90 volt DC range, powered by larger solar arrays. Solar pumping systems can also be used to pump surface water from streams or lakes to tanks at higher altitudes.
Pump controller. In addition to the separate terminals for connecting the pump to the solar module, the solar pump controller will also include a terminal block for the optional float switch that can be used to stop the pump when the tank is full or the well water level is too low. Although it is theoretically possible to connect a direct current solar cell directly to a solar array, the solar cell controller provides a number of special features that improve system performance and provide overload protection for the pump motor.
For example, in the early morning and evening hours, the solar array may not be able to supply enough current (amps) to allow the pump motor to start. However, some pump controllers can convert excess array voltage to higher currents instead of maintaining this stall condition with the motor windings warming up, which forces the pump to start pumping in dim conditions.
While the reduced voltage during these periods will not allow the pump to operate at full speed, additional water flow will be available when the system typically does not pump at all. The solar pump controller also provides a convenient place to manually turn the pump on and off for maintenance, and LED lights indicate system status. I highly recommend that any solar pump system include a pump controller.
Solar modules. The solar module should be placed as close as possible to the pumping position to reduce the voltage drop across the wire. If located in the northern hemisphere, the array should face south. The southwest direction will be good for cloudy mornings and blue sky afternoons. For most farm and range applications, you should install the module and pump controller on a steel pipe that is at least 8 feet high to keep it above the snow pile and mitigate any damage that may be caused by the animal and mowing equipment.
The rod holder also allows you to adjust the array tilt and east-west orientation during initial setup. A slant angle equal to the latitude of your location usually provides the best overall performance throughout the year. This will be in the 30 to 40 degree range of the southern half of the United States and 40 to 50 degrees in the northern half.
Well cap. The well will have a protective cover on top of the well casing from which it will leave the ground. All submersible well pumps will include a stainless steel eyebolt or threaded hole in the pump cover to attach the eyebolt. This way you can use a nylon cord to suspend the pump, which prevents the power cord from being pulled and reduces the risk of the pump pulling out of the pipe and falling to the bottom of the well.
Most solar pumping kits will include a replacement manhole cover with a straight-through fitting for the water pipe, a gland for the power cable, and matching eyebolts on the bottom side to tie the safety rope.
Float switch. Whether you are pumping from well water or surface water sources, both systems use a float switch to turn the pump on and off depending on the level of water in the stock or storage tank. The use of water storage tanks or larger water storage tanks will provide more alternative water storage capacity to carry your livestock through limited days of pumping in cloudy weather.
Antifreeze relief valve. If the temperature in your area is very low in winter, you can install an antifreeze relief valve below the frost line, but above the still water level in the well. As long as the above ground pipe is inclined from the discharge point to the wellhead, the antifreeze relief valve will allow any remaining water in the pipe to be drained back into the well each time the pump is turned off.
How Much Water for Your Livestock?
Before you start, you need to know the size of the system you are installing. To do this, you need to determine how much water your livestock needs every day. This is not as easy to calculate as you might expect, as different animals will have different drinking needs at different stages of development. In addition, depending on the season, the ambient temperature, the type of feed they are consuming and whether they are breastfeeding, all of your livestock will have different daily drinking levels.
To help determine the size of the system for different types of livestock, the “Daily Drinking Water Requirements” table in the photo slide provides an approximate range of temperate climate water usage for the most common animals, but the range will be due to the variables listed previously.
While most solar systems pump water directly into storage tanks, systems that serve many animals may first pump a large above-ground storage tank that holds thousands of gallons of water. Tanks need to be located at a higher height than the tanks, allowing gravity flow ducts to supply them. Mechanical float valves are available to release water from larger tanks when needed and then shut down when not needed.
Unlike a standard grid pump, it provides a nominal gallon flow 24 hours a day, with the solar pump's flow changing from no-flow in the evening to early morning to maximum flow near noon. If the clouds cover too much, it may not pump in bad weather.
However, for approximate summer average performance in most parts of the United States, solar pumps typically operate between 9 am and 3 pm. When the solar array is facing the south, or from 10 am to 4 pm. An array facing southwest. This is an average of 6 hours of pumping per day in summer. During this daily time window, you can expect the pump to run at full load for about two hours, 75% capacity for another two hours, 50% capacity or less, when you leave noon. In the winter, this will be reduced to about four hours of pumping per day.
Since the solar pump system can only be pumped in sufficient sunlight, the solar pump should be allowed to pump continuously from sunrise to sunset and should only be stopped when the float switch indicates that the tank is full. By adding an elevated tank, as long as the solar pump is not running, any water not required by the tank can be obtained immediately.
What size of a Solar Pump?
The size of the pump is based on a given amount of "head feet" of flow rate and is referred to as the "total head". The total dynamic head is the vertical lift of the water, in feet, from the water level up to the tank or higher discharge point, plus the head loss caused by the friction between the pipe and the pipe fitting between the two points.
While larger diameter pipes will result in less head loss due to friction, you do not want the pipe to be oversized from pump to tank because most solar pump systems operate at lower pressures and flow rates than larger grids. AC pump system. If the flow rate is too low, the water may not have enough speed to carry sand or gravel from a small pump located near the bottom of the well to the surface. Typically, a tube flow rate equal to or greater than 2.6 feet per second will alleviate this problem. Check the Flow Rate (feet per second) table in the photo slide to ensure that the flow rate of the pipe size exceeds this minimum.
For a design example, we will use an advertising solar pump that pumps 4 gallons (GPM) at a total head pressure of 100 feet per foot during normal power supply. Referring to the “Foot of Every 100 Feet Head Loss” table in the photo slide, you will see a flow rate of 4 GPM through a 12-inch PVC pipe, which will result in a head loss of 17.1 feet per 100-foot pipe, which is quite high. . Note that these table values are the head loss feet per 100 feet of pipe, so if your application requires 250 feet of pipe from the water source to the tank, you need to multiply the table value by 2.5 (250÷100 = 2.5). Similarly, if your application only requires 65 feet of tubing, you need to multiply by 0.65 (65÷100 = 0.65).
Knowing the total dynamic head will help you choose the right rated pump for the flow you need. For example, if you are pumping 4 GPM of water through a 80-foot 12-inch PVC pipe from a still water position 40 feet downhole to a nearby water tank 10 feet above the ground, the total dynamic head of the system will be 63.7. This is the way to divide the calculation method.
40 feet + 10 feet = 50 feet of head due to elevation
17.1 feet of head loss per 100 feet of 12-inch PVC pipe
× (80 feet of PVC pipe ÷ 100 feet of PVC pipe)
= 13.7 feet of head loss due to pipe friction
50 feet of head + 13.7 feet of head loss
= 63.7 feet of total dynamic head
Because our example pump is specified to provide 4 GPM at 100 feet of total dynamic head, the proposed system should be within the pump's capacity range. However, if the tank is above the hillside, the pump flow rate will drop, assuming everything else remains the same.
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