|Can I use the sun to power a pump?
Any renewable energy source can make the electricity you need to power appliances, including pumps. Solar electric cells convert sunlight into DC electricity that can be routed directly to DC appliances, or can be stored in batteries for use when the sun is not shining, or can be inverted into AC electricity to power AC appliances.
Solar well pumping generally refers to the use of sunlight to power pumps, while the sun is shining. These are simple systems that do not incorporate batteries for storing electricity. In essence, the water tank or cistern acts as storage. If you can pump water fast enough and your cistern is big enough, then you do not need to pump during the night or during cloudy days.
Batteries are generally not necessary in remote water pumping situations, as long as your system is sized properly and you have enough water flow from the water source.
Is solar water pumping economically feasible?
The reliability and economy of solar electric power make it an excellent choice for powering remote water pumping. Cattle ranchers all over the world are enthusiastic solar pump users. Their water sources are often spread over many miles of rangeland where utility power is not accessible and where refueling and maintenance costs are high for generator use.
If your water source is more than 1/3 mile from utility power, solar is a favorable economic choice. This fact is substantiated by a number of rural electric cooperatives across the U.S. These co-ops actively promote use of solar pumps because the cost to extend new power lines is prohibitive.
Where do solar pumping systems work?
Solar panels should be located in a sunny spot where no shading occurs. Altitude is not a factor, but height off the ground will affect whether or not you are able to keep them clear of snow.
Panels should be angled optimally for solar gain, particularly during the shorter winter days. If your site is in the northern hemisphere you should point your panels to true south. The reverse is true for places in the southern hemisphere. For many locations there is quite a difference between magnetic south and true south, so you should consult a declination map before setting your mounting structure.
The solar panels should be tiled up from horizontal to get a better angle at the sun and to help shed rain and snow. For best year round power output, with the least amount of maintenance, you should face the solar panel(s) true south at a tilt angle equal to your latitude with respect to the horizontal position.
If you are able to adjust the solar panel seasonally, a good rule of thumb is:
- Latitude minus 15 degrees in the summer
- Latitude in the spring/fall
- Latitude plus 15 degrees in the winter