Southeast Australia at greatest risk of ‘solar droughts’, but extreme events are rare

Analysis of high-resolution satellite data shows that southeastern Australia is at greatest risk of ‘solar droughts’ due to extended periods of low sunlight, while inland regions are least likely to experience persistent cloud cover.

The proportion of Australia’s total electricity generated by solar panels has been rapidly growing in recent years, and will increase further as the country transitions to net-zero carbon emissions. This transition is an urgent requirement to limit further negative impacts from human-caused climate change. 

To maximise solar energy production and achieve a resilient power grid, it is vital to understand how, when and where the sun shines most often on the different parts of Australia.

21st Century Weather researchers based at the University of Melbourne, together with the Bureau of Meteorology, used high-resolution satellite data to confirm that periods of low sunlight are most common in southern Australia during winter. 

‘Solar drought’ events in this region are driven by the shorter length of day and the sun sitting lower in the sky, with cloud cover found to be consistent year-round.

In tropical Northern Australia, shorter interruptions occur in summer due to thunderstorms. Inland regions away from the coast are the least likely to experience a ‘solar drought’, because persistent cloud cover is less common in these areas. Midday was shown to be the most consistently clear part of the day across all of the renewable energy zones included in the study.

Perhaps most importantly, there was often a correlation between the solar droughts in the southeast, meaning multiple renewable energy zones in this region were impacted at the same time. 

However, the good news is that the risk of negative impacts from solar droughts is lowered by the geographic spread of solar availability, while extreme solar drought events impacting multiple regions is shown to be very rare. 

The findings highlight the need for complementary sources of energy (like wind power), better storage, or access to solar from different parts of the country to mitigate the impact of these droughts.   

The researchers called for future work to assess solar availability in closer connection to wind power, hydroelectricity and energy demand, including in the context of extreme or high-impact weather events, like storms and heatwaves.

To read the full study, go to: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025GL119795.