South Australian rooftop solar pushes state-wide electricity demand to record low

South Australia’s high rooftop solar penetration has helped to deliver record low demand for the state over the weekend, hitting 786MW at around 2pm on Sunday.At the time, rooftop solar accounted for 36 per cent (445MW) of electricity demand in the state, generated by the 761MW of small-scale rooftop solar on homes and businesses in the state.

South Australia is the nation’s first region where rooftop solar PV has caused a shift in minimum demand from night time to the middle of the day.
But the new record – cited on Tuesday by Australian Energy Market Operator chief executive Audrey Zibelman as an example of how the grid is changing – is notable, not just for the time of day it occurred, but for the time of year: not in summer, as had been forecast by AEMO, but in early spring.

According to an AEMO analysis released in July, the previous record low of grid demand in South Australia occurred on November 6, 2016, with 800MW.

AEMO has predicted that by 2019, record low demand may fall to just 354MW, and within 10 years the grid demand may fall to zero because of the increasing amount of rooftop solar, particularly as South Australia has high grid prices, due to its historic legacy of an elongated network and the lack of competition in wholesale market.

“Minimum demand generally happens in summer,” it suggested. Not this time, though, because it occurred just 11 days after the end of winter.

Zibelman told a Melbourne public forum on “2017 energy sector strategic priorities” on Tuesday that she had “spent the weekend” watching the load curve in South Australia, “the lowest curve we’ve ever seen, because of all the solar.”

She used this to explain how the grid was changing because of these new technologies. “This is not a bad thing,” she said, but it required a different approach to the grid and improved management.

“It’s about managing demand more efficiently, using our resources better, to create a more efficient system.”

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Giles Parkinson