More than just “fuel saving:” How rooftop PV slashed grid demand in middle of heatwave

The last 3 days (January 7-9) have all had extreme electricity demand on Australia’s National Electricity Market, courtesy of the extraordinary heatwaves that swept across the country.

When you include demand met by rooftop solar, the demand peaks rank as #1, #4 & #2 all-time respectively.

Thankfully, wind and solar generation were excellent, as they typically are on extreme demand days. They are certainly doing more than just ‘fuel saving’ as some like to claim.

If you look at the 10 highest demand days since 1/1/2023 (including demand met by rooftop PV), then rooftop has reduced peak demand levels by an average of 14%.

When you look at demand net of rooftop & utility PV, the average reduction is 17%.

When you look at demand net of all PV & wind, the average reduction is 28%.

A similar story is seen in all states except Tasmania, which has peak demand in winter. In Tasmania, solar makes negligible contribution to reducing peak demand, though wind does.

The last table shows the dates of peak NEM demand and demand net of solar & wind.

Note that once you exclude rooftop PV from demand, the peak dates sometimes occur in winter.

Note I’ve only analysed data post 1/1/2023. While virtually all peak total demand events have occured after that date, many peak demand excluding rooftop PV events occured before then.

All data in this post is from the OpenElectricity website.