While it is well-established that the solar resource of the East does not match that of the West, the Atlantic Coast has a large volume of operational capacity and it is therefore of critical importance for project operators in the region to understand the reasons behind below average energy output and whether it is due to malfunctioning equipment or weather variability. 

 

Vaisala's 2014 study illustrates the impact of short-term, month-to-month weather variations on performance at U.S. solar projects and places them into a long-term context. This reveals frequent and significant deviations from long-term average irradiance conditions and highlights the clear requirement to analyze the effect of solar resource variability on both over and underperformance.

 

From an annual perspective, this year's weather patterns had an adverse effect on a large number of installations along the Atlantic Coast from Florida to Massachusetts, as well as Texas, while the bulk of projects in California and the Southwest saw an uptick in solar irradiance that may have increased overall 2014 production at many sites. 

 

However, these annual variations only offer a high-level view of project performance. Vaisala also conducted a monthly analysis that gives a much more robust understanding of how specific weather conditions affected solar production throughout the year.