Across the contiguous United States, extreme weather conditions dominated the third quarter of 2017 and brought departures from long-term average global horizontal irradiance, a proxy for PV plant production. GTM has partnered with Vaisala, a company that regularly monitors solar performance across the U.S., to give the solar industry a better understanding of how these weather trends are driving solar performance around the country. This allows the industry to reconcile project performance by comparing it with recent solar conditions and putting this in context with long-term average conditions.