Rooftop solar hits record 52 pct share in Australia’s most coal dependent state

Rooftop solar has achieved a record share of generation in Queensland, the country’s most coal dependent grid despite being known as the “sunshine state”, and at the same time sent operational demand to a record low.

The share of rooftop solar achieved a record instantaneous share of 51.9 per cent of underlying demand at 12.40pm on Sunday, according to the data analysts at GPE NEMLog.

They say it is the first time this share has exceeded 50 per cent, and beats the previous record of 49.7 per cent set at 11.35am on October 1 last year.

At the time of the new record, GPE’s Geoff Eldridge says, Queensland’s rooftop solar PV output was 3,898 megawatts (MW). That’s not a record – the peak is 4,151 MW on November 30 last year but because overall demand was lower the share of rooftop PV was higher.

The dominance of rooftop PV also created a new record low for instantaneous operational demand of just 3,096 MW, down 35 MW from the previous low set last October, according to Eldridge.

Other states have high shares of rooftop PV and deeper lows for operational demand – South Australia reached more than 101.7 per cent share on December 31, and operational demand was minus 26 MW – but the significance of the new milestone in Queensland is that it remains Australia’s most coal dependent grid.

Queensland has more than 8.1 gigawatts (GW) of coal fired generation capacity – and a coal share of generation of 67.6 per cent in the past 12 months.

But when the new rooftop PV output record was set on Sunday, coal output was just 3.2 GW, and it was only that high because the state was exporting around 1.2 GW of capacity down south to neighbouring NSW. That means that more than 5 GW of coal capacity was not switched on.

Most of Queensland’s coal fired generation is expected to shut down over the next decade and the state Labor government has a target of 80 per cent renewables by 2035 – up from around 29 per cent now, still the lowest in the state.

As this graph above illustrates, South Australia was the first to reach a 50 per cent share for rooftop solar back in 2018, and Victoria followed in 2021 and NSW – the biggest state grid in the country – in 2023.

Eldridge believes that the National Electricity Market as a whole will reach instantaneous 50 per cent share for rooftop PV in the next few months. Its peak is 48.8 per cent, reached in October last year.

As the share of rooftop solar PV continues to grow, it is difficult for “baseload” power sources that like to be “always on” to find a place in the market, given that rooftop PV delivers cheaper power to its home owners and lowers prices for other.

And just as it is now increasingly eating the midday lunch of coal fired power generation, it would do the same thing to any nuclear power plants that might be built if ever the Coalition policy turned out to be a thing in about two decades time.

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