Even if you couldn’t step outside to watch the solar eclipse take place today, it was still possible to participate in this historic event. No, not just by watching the NASA livestream -- but by curbing your electricity usage.
The eclipse will affect around 1,900 utility-scale solar PV power plants across the U.S. today, causing an estimated 9,000 megawatts of solar capacity to go offline as the moon passes in front of the sun. California alone was projected to lose 6,000 megawatts of solar capacity. Generation profiles from the California Independent System Operator show a roughly 5,000-megawatt drop shortly before 12 noon.
All of this generation had to be made up for somehow. The data shows that hydropower and natural-gas-powered turbines largely carried the burden of compensating for lost solar output. Energy storage may have also played a role.
While these large-scale, high-tech responses are critical, the influence of the individual electricity consumer cannot be underestimated, said Michael Picker, president of the California Public Utilities Commission (CPUC). In fact, consumers have to start thinking more about how their energy use fits into a larger system due to the grid needs even on non-eclipse days.
“It’s not clear that we’re going to get people to unplug enough major appliances to result in a 6-gigawatt energy savings for a 2-hour period, but soon we will be asking for that,” said Picker. “We're moving toward a time-of-use program in California, and so [the eclipse] becomes a way to explain to people who believe that just building more solar would solve the problem that it's more complicated.”
Residential solar customers in California are already moving to time-sensitive electricity rates. By 2019, all residential customers will switch to a time-of-use (TOU) plan, incentivizing customers to use energy at off-peak times, enabling them to save money while helping their utility manage peak demand.
The peak, preceded by a fast ramp as solar generation fades (widely known as the duck curve), is only getting more pronounced in California. An analysis of CAISO data from 2011 through mid-2016 by consultancy ScottMadden reveals that California has largely exceeded its 2013 projections for lower net loads and higher ramps in energy demand.
Managing this issue is “going to require people to actually start to think about how their power making choices,” said Picker. “Whether it's to get a rooftop solar panel or to move to a ground-mount geothermal water heater, or to get more energy-efficient appliances -- all these things that they do will also have kind of a time-bound aspect. They need to not just do these things, but they need to think about how and when they do these things.”
Today’s eclipse is a test run for the electricity community. Leading up to the event, the CPUC received commitments from nonprofits and public awareness groups like Energy Upgrade California, as well as the State of California’s real estate manager, private companies like Google and third-party technology providers to help roughly 500,000 people take steps to reduce their energy usage during the eclipse hours.
Nest is one of those third parties. Over the weekend, the company rolled out an update asking Nest thermostat owners if they wanted to participate in a special Solar Eclipse Rush Hour program that encouraged people across the U.S. to help offset the drop in solar production by precooling their homes. The thermostat’s onboard sensors assess the conditions in each home, including the number of occupants and thermal characteristics, then it automatically adjusts the temperature by a few degrees to reduce energy use during the “rush hour” period, while keeping customers comfortable.
“This is definitely unprecedented scale not just for Nest, but really for anybody,” said Ben Bixby, general manager of energy and safety at the Google-owned company. Nest launched its Rush Hour Rewards program in 2013 to help customers use less energy when everyone else is using more. Today, more than 70 U.S. utilities regularly call on the Rush Hour program. But never before has the company issued a call to millions of Nest customers across the U.S.
The eclipse program is “the world’s largest clean distributed power plant,” said Bixby, who expects to help offset a “good amount” of the drop in solar supply through demand-side management.
“This is a novel point in history and technological capabilities to demonstrate at gigawatt-scale that connected devices are a resource on par with peaker power plants,” he added.
When the last solar eclipse passed over the U.S., there wasn’t any solar capacity to offset, or any internet-connected devices capable of responding to the drop -- in fact, there wasn’t even an internet. Today, grid needs are vastly different, and customer-sided technologies are responding -- not only during eclipse conditions, but also on a day-to-day basis.
“What we've been stressing to people is the situation that we're seeing with the eclipse is actually like 12 to 15 hot summer days where the sun is going down in the west, and south-facing panels start to really lose their overall capacity for generation because they're not getting direct rays from the sun. This is also the same time when people are coming home from work and turning on their air conditioning,” said Picker. “So we have exactly the same challenge on a regular basis within the grid because of solar and the way that it works. It's just a matter of figuring out if the sun goes away what we can do as consumers and decision-makers to make up the difference. That's what helps us to avoid having to depend on these natural-gas peakers.”
“Frankly, engaged customers are far more efficient than battery storage,” he added, when asked what roles he sees various technologies playing.
Picker pointed to Sacramento Municipal Utility District’s TOU pilots as evidence of this. The two-year study, conducted in partnership with the Rocky Mountain Institute, successfully reduced demand by nearly 12 percent during the peak period. With a larger price differential, the utility was able to shave around 25 percent of load during peak hours on peak days.
The results suggest that if around 15 percent of SMUD's customer base could reduce their load on 12 peak days in the summer, the utility could avoid building 500 megawatts of gas peakers, said Picker. “That’s not chump change; that’s a big deal.”
“If we can get that kind of response statewide, that's a huge savings to the system. It comes cheap compared to building battery arrays, and it comes cheap compared to building large capacity storage or new peaker plants,” he added. “So it's absolutely important for us to explore [demand-side management] and to figure out how to make it work. Plus, it gives people more choices.”
Results from the SMUD TOU pilot in 2016 bear this out.
California’s three large investor-owned utilities will launch their own TOU pilots next year to see how consumers respond to new pricing signals to alter their energy use at specific times. Consumers have yet to learn how important they are to the larger grid network, and it goes beyond purchasing efficient appliances, home solar or a even a battery, said Picker. It’s how they behave during a small period of time “that makes an enormous difference,” he said.
Charlie Gay, director of the Solar Energy Technologies Office at the Department of Energy’s Office of Energy Efficiency and Renewable Energy, is thinking along similar lines.
“A lot of what we do in solar, and part of the reason I came here to DOE almost a year ago, was to collaborate more closely with folks who happen to be five doors down the hallway from me here in the Buildings Office,” he said. Combining solar with energy efficiency “helps keep electricity costs down and helps us make better use of the existing infrastructure that we've already paid for with all of the wire.”
The DOE’s solar experts are teaming up more and more with the Buildings Office to study the interplay between distributed solar and advanced heat pumps, as well as advanced lighting, hot water heaters and smart air conditioning systems. What makes these devices smart is their ability to communicate, which is where home automation comes into play. Historically, distributed energy resources didn’t have a large enough presence on the grid to play much of a role in grid reliability, but “now that all of us have made so much headway with these technologies, it's much more important that we team up with other offices at the DOE to think of the network [and] the system as a whole,” Gay said.
As for the eclipse, “I think it’s a great teachable moment,” he said. “I don't think consumer behavior with regards to how much electricity consumption changes is going to be all that noticeable, because it's a fleeting moment in time, but the attention that the eclipse [draws] just naturally brings…relevancy to solar and choices that individuals can make.”
The DOE, Nest and a myriad of technology developers and research groups are working on ways to better integrate solar on the grid. When the next eclipse passes over the U.S. in 2024, it’s possible the consumer impact will be much more noticeable.