On Feb. 24, the California Independent System Operator (ISO) reported a new all-time solar generation peak of 8,792 MW on its power grid. That instantaneous production high, reached at 1:42 p.m. PT, beat the ISO’s previous solar peak record of 8,545 MW, which was set on Sept. 14, 2016. More broadly – and perhaps more importantly – the new ISO record also underscores the ongoing success of California’s renewable portfolio standard (RPS).
“The state of California has one of the most aggressive renewables policies in the U.S., with utilities mandated to procure renewables that will serve 50 percent of their retail sales by 2030,” says Steven Greenlee, a California ISO spokesperson. “The solar peaks the ISO are seeing reflect that the utilities have been actively adding renewables to their portfolios, more renewable generators are interconnecting to the grid, and in turn, higher and higher amounts of solar energy are generated on our system. It also means that the energy used in California is becoming cleaner, thus reducing greenhouse-gas emissions produced by in-state power plants.”
Greenlee points out that the ISO reached a new solar peak over a dozen times in 2016 alone. “As more solar is interconnected to the system, we expect to see more solar peak production records set,” he says.
In addition to the solar peaks, Greenlee continues, “We also are seeing renewables – driven by wind and solar – serving a larger portion of our load.” For example, he says renewables served a whopping 54% and 56% of the ISO’s load on May 14 and May 15, 2016, respectively. “Renewables often will serve about 30 percent of load.”
California’s 50% by 2030 RPS is, without a doubt, spurring the development of more clean energy. Greenlee says that as of Dec. 31, 2016, RPS resources – including solar, wind, geothermal, small hydro, biofuel, and battery energy storage – made up approximately 28% of the resources interconnected to the ISO grid. Solar accounted for almost 50% of that total, followed by wind at 30%.
According to Greenlee, about 2 GW of solar generation was added to the ISO grid from June 2015 to June 2016, which mirrored the amount of solar previously added between June 2014 and June 2015.
“We expect this trend to continue as the utilities work to meet the state’s RPS 2030 deadline, which will require about an additional 15,000 of RPS resources, with a significant amount of that capacity expected to be in the form of solar,” he explains.
However, the meteoric growth of California renewable energy isn’t without its challenges.
Greenlee says, “The ISO has also analyzed the challenges associated with adding thousands of megawatts of renewables, with solar composing the majority.” Although the ISO is currently in the process of updating its so-called Duck Curve analysis, Greenlee suggests one of the operator’s main concerns remains managing future oversupply conditions.
An ISO fact sheet explains, “Oversupply is when all anticipated generation, including renewables, exceeds the real-time demand. The potential for this increases as more renewable energy is added to the grid but demand for electricity does not increase. This is a concern because if the market cannot automatically manage oversupply, it can lead to overgeneration, which requires manual intervention of the market to maintain reliability.” The ISO says such intervention could include ordering renewable energy power plants to curtail or cease production.
The fact sheet adds, “In almost all cases, oversupply is a manageable condition, but it is not a sustainable condition over time – and this drives the need for proactive policies and actions to avoid the situation.”
Greenlee says, “Among the mechanisms to help manage oversupply is to find demand to use the excess energy.” He notes that is why the ISO supports S.B.350, which in addition to increasing California’s RPS in 2015, “instructed the ISO to study the impact of expanding the ISO’s service area beyond state borders and become a multi-state grid operator in the western U.S.”
Greenlee says the western Energy Imbalance Market (EIM), a real-time wholesale energy market the ISO launched at the end of 2014, is one “tool” currently available.
“Now with four utilities serving consumers in eight western states, the real-time market helps participants meet their own demand with low-cost excess energy, thus avoiding renewables curtailments,” he says. According to a recent ISO report, the western EIM has so far produced millions of dollars in benefits and displaced a significant amount of CO2 emissions.
Thanks to its RPS, California is guaranteed to have even more renewable energy in the future, and solar in the Golden State will keep setting new peak generation records. As a result, the ISO will undoubtedly continue working to maintain reliability on one of the world’s biggest and greenest power grids.