3TIER, a provider of renewable energy information services, has released maps that the company says illustrate how solar irradiance varied from its normal monthly averages across the U.S. from June through August 2010.
The maps dispel a popular perception that solar energy is relatively consistent from year to year and underscore the need for thorough resource assessments prior to investing in solar projects. Variances in solar irradiance, which are caused by short-term weather anomalies, have a significant impact on the long-term economic viability of both distributed and utility-scale solar power development, according to 3TIER.
‘The patterns observed in the solar maps correlate well with the series of weather events that affected the U.S. during these same months,’ says Dr. Bart Nijssen, senior vice president of technology at 3TIER. ‘The variances are quite significant, often in excess of plus or minus 20 percent of normal.’
The monthly maps for both global horizontal irradiance and direct normal irradiance and a more detailed summary of the study can be found here.