Rooftop solar delivers generation milestone in NEM


Both South Australia and Victoria set new records for low demand for electricity from the grid on the final day of 2023 with mild temperatures and clear skies driving high rooftop solar generation, which contributed more than 100% of South Australia’s total energy needs and accounted for almost two-thirds of Victoria’s energy requirement.

On 31 December 2023, in the 30-minute period starting 12.30pm, rooftop solar provided 65.8% of Victoria’s energy needs, up from the previous high of 61.5% seen on 17 December 2023. In South Australia, rooftop solar provided 101.8% of the state’s total energy requirement on New Year’s Eve, a slight increase on the 101.1% share seen on 23 September 2023.

The Australian Energy Market Operator (AEMO) – which noted in its recently released draft 2024 Integrated System Plan (ISP) that rooftop solar is now three times more common than backyard pools in Australia – said the South Australian milestone is the first time rooftop solar exceeded total demand in any region of the National Electricity Market (NEM).

Both states witnessed their lowest-yet half-hourly operational demand levels with South Australia’s demand dropping to -26 MW in the half hour ending 1.30pm, down from the prior record of 5 MW on 1 October 2023. In Victoria, demand fell to 1,564 MW at 1pm, a decrease from the previous low of 1,915 MW recorded on 29 October 2023.

The high rooftop solar generation saw market prices in both regions drop. Daily wholesale electricity prices averaged -$66.54/MWh in South Australia and -$73.02/MWh in Victoria, nearly $20/MWh below that state’s previous daily low.

Large-scale solar and wind scaled back in response, with some observers noting the event marked a significant shift in Australia’s electricity generation landscape.

While the increase in rooftop solar installations poses a risk for system security, market analysts pointed out that it also presents opportunities, including for increased energy storage capacity – grid-scale storage, home batteries and electric vehicles – to ensure grid stability during times of excess solar rooftop generation.

AEMO has forecast that rooftop solar capacity will triple from just over 20 GW today to 60 GW by 2040.

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