Mild temperatures and sunny skies helped California set two new solar records in recent days.

On Sunday, March 4, the California Independent System Operator saw an all-time peak percentage of demand served by solar, hitting a record 49.95 percent at 12:58 p.m. That's up from the previous peak of 47.2 percent set on May 14, 2017.

"The record is a result of a cool, sunny day," Anne Gonzales, senior public information officer at CAISO, wrote in an email.

"Because it was a weekend, and the weather was mild, the minimum load was relatively low, around 18,800 megawatts," she said. "Meanwhile, solar production was more than 9,400 megawatts."

A day later, on March 5, CAISO set another solar record, this time hitting a new peak for solar production of 10,411 megawatts at 10:18 a.m. The previous record was 9,913 megawatts set on June 17, 2017.

CAISO Overall Renewables Production for March 5, 2018

It's no surprise that solar is making up a larger and larger portion of California's electricity mix. The state's three investor-owned utilities are well ahead of schedule on their renewable energy procurement plans and on track to meet the state's 33 percent mandate for 2020. At the same time, community-choice aggregators (CCAs) are investing in additional solar installations.

California's success to date is driving a conversation around the possibility of reaching 100 percent renewables in the state, while also stirring debate over how to manage these variable resources in an evolving grid system.

"The escalating integration of solar power has created a new operating paradigm for our system operators," said Gonzales. She pointed out that on March 4 the grid not only set a new solar record, but also handled a record peak for ramping.

"Our operators are skilled at handling these ramps, and we expect them to continue," Gonzales said.

CAISO is also working to reduce curtailment when there is an oversupply of renewable resources on the system, which is expected to happen more frequently as the state introduces increasing amounts of wind and solar. The ISO is currently seeking solutions to maximize the use of clean energy sources, including energy storage, demand response, time-of-use rates, expansion of the western Energy Imbalance Market (EIM) and the possibility of a regional energy market.

CAISO's fourth-quarter 2017 report on the EIM showed benefits of $33.46 million for its participants, bringing the total benefit to $288.44 million since the real-time market launched in 2014. The market also helped reduce carbon emissions in the western region by 7,730 metric tons by using 18,060 megawatt-hours of renewable energy that otherwise would have been curtailed.

The EIM currently serves consumers in eight Western states through six participating entities. Another six entities will join by early 2020, including Idaho Power and Canada’s Powerex in April 2018.

While California could break its latest solar records in the coming weeks and see solar reach even higher levels in the coming years, there's unlikely to be a significant increase in solar, or any other renewable energy resource, on the system in the near term.

Due to accelerated renewable energy procurements in recent years, coupled with departing load going to CCAs, retiring power plants and other market shifts, investor-owned utilities procured no new renewable energy capacity in 2017, according to a California Public Utilities Commission report. Furthermore, the CPUC recently proposed that utilities procure virtually no additional renewables in 2018.

"It's really disappointing," said Jan Smutny-Jones, CEO of the Independent Energy Producers Association (IEP), in a recent interview. "They're basically saying, 'There too much going on; we don't know what to do, so we're not going to do anything for a while.'"

IEP, which represents solar, wind, geothermal and small hydro developers, asked California utilities to put out wholesale solicitations for 3,000 megawatts of renewables this year. But the request was not met.

Smutny-Jones criticized the CPUC for being "too absorbed in modeling" with the expiration date for wind and solar tax credits looming. "For me, it's a little hard to sit in a meeting and talk about 100 percent renewables when our chief regulator isn't moving the ball."

This story was updated with a more recent CAISO chart on renewable energy curtailment.

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