Solar Energy and Duck Curve

Solar photovoltaic (PV) technology is being deployed to reduce dependence on fossil fuels for electricity use and associated emissions of greenhouse gases and certain pollutants. High solar adoption creates a challenge for utilities to balance supply and demand on the grid. This is due to the increased need for electricity generators to quickly ramp up energy production when the sun sets and the contribution from PV falls. Another challenge with high solar adoption is the potential for PV to produce more energy than can be used at one time, called over-generation. 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 over-generation and curtailed renewable energy, increasing its costs and reducing its environmental benefits.