What blackout? How solar-reliant power grids passed the eclipse test

August 23, 2017 by Dev Tayal, The Conversation
The path of the eclipse, shown relative to the positions of major US solar power installations. Credit: US Energy Information Administration

The total solar eclipse that captivated the United States this week was more than just a celestial spectacle (and a reminder to take care of your eyes). It was also a valuable lesson in how to manage electricity grids when a crucial generation source – solar power, in this case – goes temporarily offline.

The last to pass over the US was in 1979, a year when President Jimmy Carter was in the midst of the crisis and struggling with ballooning oil prices. In response, he made a concerted shift to greater energy independence through such as solar.

In 2017, almost the whole world is grappling with the transformation of the electricity industry and the move to renewable energy.

Eclipses have – and always will have – a lot to teach us. While this eclipse did not cause major disruption to the US electricity network, it gave system operators a better understanding of how future intermittencies can be managed.

Despite the rapid decline and rebound in solar power output during the event, operators were able to manage without a hitch. Their thankless task reminds us of the importance of having resilient and robust electricity systems with sufficient backup capacity.

Solar plants lost around half of their ability to generate electricity during the two and a half hours of the eclipse, dipping and rising almost three times faster than the average rate at which power stations can ramp their output up and down. The shortfall was covered largely by gas-fired power plants, and extra hydro capacity.

California faced a particularly tough challenge because of its relatively high level of renewable energy; last year 10% of the state's electricity came from solar photovoltaic (PV) power.

Given the recent scrutiny on Australia's beleaguered , it makes sense to ask how our power system would fare if faced with the same challenge. Take a walk through almost any suburb and you'll see dozens of solar panels glinting from roofs. How much have they destabilised our ? Would we pass the eclipse test?

System managers and market operators such as the Australian Energy Market Operator already intricately balance demand and supply levels throughout the day, and must deal with unexpected outages at power stations, extreme weather events (think of South Australia), and increasingly predict how the share of intermittent generation from renewable resources will be matched and secured.

According to the Clean Energy Council, Australian renewables provided 17% of the country's electricity generation in 2016. In world terms that looks rather unimpressive. But this figure does not reflect the growing impact of behind-the-meter solar PV that is slowly but surely reducing reliance on grid electricity during the day.

California’s solar output during the eclipse. Credit: California ISO

As outlined in a previous FactCheck, Australia has the highest proportion of households with PV systems on their roof of any country in the world, at over 15%. (However our total energy produced from solar is somewhat less than Germany, Italy, Belgium and Japan, which have a propensity for larger systems).

Of course, all this distributed solar adds to the complexity for utilities and grid operators, and underpins why we have technical rules and connection standards to ensure that households connecting individual systems to the grid do not cause unintended consequences for local network areas. As the forecasts for rooftop solar installations continue to be revised upwards, AEMO nevertheless remains sanguine about the potential for grid disruption:

"…it is technically feasible to integrate this amount of rooftop PV into the network over the forecast horizon, through a mix of market, network, and non-network (such as storage) solutions to address issues such as increasing variability in system demand, low daytime demand, and increased ramping at morning and afternoon electricity system peaks."

Utilities themselves are acutely aware of the "non-negotiable social contract of keeping the lights on", as mused by Frank Tudor, chief executive of Western Australia's regional utility Horizon Power, in an opinion piece written before the eclipse. The emboldened South Australian government may take further comfort in the fact that its newly minted 150-megawatt Aurora Solar Energy Project would come into its own during such weather interruptions (more often due to clouds than eclipses), with its capacity to store in molten salt storage tanks, to be dispatched as required during peak periods.

Lean and green machines

The eclipse also underlines how crucial the innovations in technology and data analytics will be in ensuring that electricity grids can still operate seamlessly as the share of renewable energy grows.

We are seeing this already in many small, isolated power networks across the country, where microgrids, particularly in coastal tourist towns with a proclivity for clean technology, are already pushing the limits of hosting capacity and driving utilities to explore big data solutions to assist with the integration of increased levels of solar PV.

One such example is the sky camera trial being conducted in Carnarvon, Western Australia, that will track weather patterns and anticipate cloud cover to help with grid stability. The trial is using machine learning to help predict the impact of weather on the grid, and to balance the fluctuations with other energy sources, thus helping the network to withstand such events without losing reliability.

With our energy systems becoming ever more distributed and decentralised, the US eclipse provides another of nature's lessons on the need to be smart about creating resilient networks.

The next total solar eclipse for Australia will be in 2028, and will pass straight over Sydney. In the meantime, a hybrid eclipse will cross Australia's northwest in April 2023.

Time will tell how much of an impact these events will have on our power grids. But given the importance of electricity for our health, wealth, transport and so much more, let's hope our system operators and policy makers aren't blindsided.

Explore further: New solar forecasting tool could help increase efficiency and reduce energy costs

Related Stories

No more cloudy days for solar

June 14, 2012

For a country with so much sunlight, some might think Australia has been slow to adapt its electricity generation mix to include solar power. One of the main reasons for this is solar intermittency.

Recommended for you

Click beetles inspire design of self-righting robots

September 25, 2017

Robots perform many tasks that humans can't or don't want to perform, getting around on intricately designed wheels and limbs. If they tip over, however, they are rendered almost useless. A team of University of Illinois ...

New technique spots warning signs of extreme events

September 22, 2017

Many extreme events—from a rogue wave that rises up from calm waters, to an instability inside a gas turbine, to the sudden extinction of a previously hardy wildlife species—seem to occur without warning. It's often impossible ...

6 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

WillieWard
2.3 / 5 (3) Aug 23, 2017
"solar-reliant power grids passed the eclipse test"
It's thanks to gas/fracking(the best friend of intermittent renewables).
aksdad
4 / 5 (4) Aug 24, 2017
Congratulations! California survived a dip in solar energy output for a couple hours thanks to reliable electricity from base load fossil fuel, nuclear, and hydro power plants. Woohoo! Oh wait, they do that every night and on days when clouds and storms obscure the sun.
gkam
1 / 5 (2) Aug 25, 2017
Perhaps you "forgot" about our solar thermal, hydropower, geothermal, pumped storage, and other non-fossil sources?

Certainly you knew about them, . . didn't you?
WillieWard
3 / 5 (2) Aug 25, 2017
Four trillions of dollars spent for almost nothing
Intermittent renewables, the most expensive scam of the history
"In 43 years fossil fuels lost 4 points of market share in world energy supply, but in absolute terms their consumption increased."
https://pbs.twimg...GWrb.jpg]https://pbs.twimg...GWrb.jpg[/url]
https://pbs.twimg...GWrb.jpg]https://pbs.twimg...GWrb.jpg[/url]
"The share of electricity production from renewables has barely increased between 1990 and 2014 (from 19% to 21%)"
https://pbs.twimg...=600x314
https://ourworldi...OWID_WRL
"Worldwide investment in renewable energy reaches US$ 4 trillion – with little to show for it"
http://euanmearns...-for-it/
It's hard to spot them:
https://uploads.d...eac3.jpg
MR166
3 / 5 (4) Aug 25, 2017
Lets see, the eclipse affected about 75 square miles at any one time. Plus that it was totally predictable vs cloud cover which can change very quickly and cover 1000s of square miles. If anyone considers that to be a test they are delusional and need to seek professional help.
barakn
3 / 5 (2) Aug 29, 2017
Lets see, the eclipse affected about 75 square miles at any one time.
That's totality. The partial eclipse, which could obscure up to 99.99+% of the sun, covered millions of square miles.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.