South Australia has met 100% of its electricity demands with solar energy for the first time over the weekend—most of it coming not from solar farms but PV panels mounted on rooftops.

A combination of cloudless skies, low energy demand, and mild temperatures helped create conditions for 76% of circulating power to be generated by rooftop solar, with utility-scale solar farms making up the rest.

Both sources combined to make 1.37 gigawatts of available power, which would have generated 986 metric tons of CO2, and would normally require 1 million pounds of coal or around 100,000 gallons of gasoline.