In 2013, the California Independent System Operator published the “duck chart,”” which shows a significant drop in mid-day net load on a spring day as solar photovoltaics (PV) are added to the system. The chart raises concerns that the conventional power system will be unable to accommodate the ramp rate and range needed to fully utilize solar energy, particularly on days characterized by the duck shape. This could result in “overgeneration”” and curtailed renewable energy, increasing its costs and reducing its environmental benefits.

Read the source: November 2015 report, National Renewable Energy Laboratory

Read the “Best Practices Handbook for the Collection and Use of Solar Resource Data for Solar Energy Applications” Feb 2015: Act Now