Optimum fixed orientations and benefits of tracking for capturing solar radiation in the continental United States

Optimum tilt and azimuth angles for solar panels were calculated for a grid of 0.10 by 0.10 National Solar Radiation Data Base (NSRDB-SUNY) cells covering the continental United States. The average global irradiation incident on a panel at this optimum orientation over one year was also calculated, and was compared to the solar radiation received by a flat horizontal panel and a 2-axis tracking panel. Optimum tilt and azimuth angles varied by up to 100 from the rule of thumb of latitude tilt and due south azimuth, especially in coastal areas, Florida, Texas, New Mexico, and Colorado. Compared to global horizontal irradiation, irradiation at optimum fixed tilt increased with increasing latitude and by 10% to 25% per year. Irradiation incident on a 2-axis tracking panel in one year was 25% to 45% higher than irradiation received by a panel at optimum fixed orientation. The highest increases in tracking irradiation were seen in the southwestern states, where irradiation was already large, leading to annual irradiation of over 3.4 MWh m.