Rooftop solar takes its biggest bite yet out of coal generators’ lunch, as home battery rebates hit 89,000

Rooftop solar on homes and businesses took its biggest bite yet out of the traditional “baseload” midday lunch on Wednesday, as the combined output hit a new record of 15,597 megawatts (MW) at noon AEST.

The new record, which beat the previous high set earlier in the month by more than 500 MW, also took the market share of rooftop solar and large scale on Australia’s main grid to a new peak of 71.5 per cent around the same time.

According to the data collectors at GPE NEMLog, that beat the previous record set more than a year ago. There was little wind output at the time.

Rooftop PV also set new output records this week in NSW (5,549 MW) and Victoria (3,818.7 MW), and while a number of big battery charging records were also established in several states – with NSW falling just short of being the second state to a gigawatt at 999 MW – the impact is being clearly felt on the grid.

Some coal generators, as we have reported, are now involved in “two shifting” coal units, switching them off at the start of the day, and then back on again in the late afternoon as the impact of rooftop PV wanes.

All the big coal generators, particularly in NSW, are having to dial down their output – some my more than 80 per cent. On Wednesday, three units were out of action for maintenance at Eraring, Bayswater and Vales Point, but the remaining units were operating at just a fraction of their capacity.

The new rooftop PV output record comes as Origin Energy, the owner of her 2.88 GW Eraring facility, hinted that the country’s biggest coal generator may not close in August, 2027, as currently advertised, and its operations may be extended again until 2029.

With the growth of rooftop solar – still running close to 3 GW a year – that will put increased pressure on the operations of so-called “baseload” generators such as Eraring, although by 2027 it should have the country’s biggest battery up and running, 700 MW and 2,800 MWh at the same site.

That could provide Origin Energy with added flexibility, although it remains to be seen how the company manages the new Eraring battery, the first stage of which is going through early commissioning.

Meanwhile, the growth of household batteries continues to surge with the help of the federal cheaper batteries rebate, which could provide the flexibility. The latest data shows that there have 89,182 home battery applications since the rebate started on July 1, for a total of 1.7 gigawatt hours.

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