With sunny skies and moderate temperatures, California's fleet of large-scale solar power plants has reached a new record peak on the California ISO grid, hitting 10,411 MW at 10:18 AM on March 5. Solar photovoltaic facilities accounted for the lion's share, peaking at 9,874 MW in midmorning, while solar thermal hit 557 MW in midafternoon.
The record solar peak came just a day after the state's grid operator celebrated solar's all-time high as a percentage of served demand, at nearly 50% in the early afternoon on March 4, amid overall soft demand exacerbated by the state's additional roughly 6,000 MW of self-generation resources, mostly in the form of rooftop solar. Later that day, the ISO registered a record ramp-up, adding 14,777 MW of generation in three hours, mostly from natural gas-fired plants and hydropower imports from the Pacific Northwest, as the sun was setting toward the ISO's system peak demand in the evening.
In other words: 'Duck curve' season is open, with its heightened springtime risks of overgeneration, negative prices and renewable energy curtailments. So far this year, however, the ISO is reporting a considerable drop in variable renewable energy cuts when supplies exceed demand. Through March 5, 2018, renewable energy curtailments totaled 49,304 MWh, less than half of the 102,992 MWh of renewable energy wasted last year through February, according to an ISO spokesman.
"It was a different grid in [January to February 2017] than today," Steven Greenlee said in an email, citing the growing western Energy Imbalance Market as one of the main reasons for the reduction in renewable energy curtailments. The market currently includes CAISO and five utilities in the West. In the fourth quarter of 2017, participants in the western EIM used 18,060 MWh of excess renewable energy that otherwise would have gone to waste, helping to cut carbon emissions in the region, the ISO said in a report in January. Sharing resources has enabled market participants to avoid 520,417 MWh of renewable energy cuts since 2015.