Rebecca Gredley
(Australian Associated Press)

South Australians are installing rooftop solar at such a rate authorities are preparing for periods the electricity grid won’t have any demand.

Australian Energy Market Operator chief executive Audrey Zibelman says 2400 South Australian homes a month are getting rooftop solar.

By December next year there’s expected to be another 36,000 homes with solar.

“Which means there will be times of year that we have actually no demand for power from the grid,” she told a Smart Energy Council forum on Wednesday.

“Which is a very challenging thing for us to manage, and we have to really now start thinking about the changes.

“From a system operation standpoint it’s not a question of policy, but it’s a question of reality – how do we change this very, very quickly.”

AEMO has seen some of its lowest ever demand recently in SA.

It is tweaking the power system so solar power created during the day is stored in order to be used later, shifting usage and demand.

There are 2.5 million rooftop solar systems in Australia, compared to 100,000 in 2010.

A panel is installed every six and a half minutes.

“We’re essentially adding a generator almost every month or two months throughout the National Electricity Market,” Ms Zibelman said.

AEMO is preparing for about 70 per cent of the electricity supply to come from renewable sources by 2030.

Over the next 20 years 63 per cent of the coal fleet will retire because of age.

They will be replaced with wind and solar, along with firming such as storage or gas, depending on the price.

Ms Zibelman on Tuesday announced her resignation from AEMO for Google X.