More than half of utility-scale solar photovoltaic systems utilize solar tracking

More than 50 percent of the operating utility-scale solar photovoltaic (PV) systems in the United States use some form of tracking technology to follow the sun throughout the day and optimize efficiency, according to the U.S. Energy Information Administration (EIA).

The weather and amount of available sunlight in a region influence how economic sun tracking technology is for that area. In the eastern United States, fixed-tilt solar PV units accounted for 80 percent of all utility-scale solar PV units operating in 2015. In states west of the Mississippi River, fixed-tilt solar PV units made up 37 percent of solar PV unit capacity. Single-axis solar PV units accounted for 56 percent.

The prevalence of different types of solar radiation in a region can also play a role in whether sun-tracking technology would be beneficial there. In the eastern United States, diffused radiation, light that is scattered by the earth’s atmosphere, is more common due to greater cloud cover. The western United States receives more direct-beam radiation, sunlight that comes from the sun to earth in a straight line, making single- and double-axis units more effective.

Single- and double axis units are also more expensive to produce and install and require more acreage than fixed-tilt units. They can, however, produce more electricity in the right conditions. For example, the National Renewable Energy Laboratory’s PVWatts calculator estimates that, annually, a 10-kilowatt PV system in Los Angeles, California, using a single-axis tracking system will produce 21 percent more electricity than a system tilted at a fixed 20 degrees. A dual-axis tracking system in the same location would generate 31 percent more than the fixed-tilt system.