The high penetration of rooftop PV in South Australia has pushed the state’s distribution network to reach for levers to control the export of solar energy. SA Power Networks is upgrading voltage management systems at about 140 of its major substations to allow it to, it claims, “facilitate more solar generation on our state’s electricity distribution network”.

The substations support about 790,000 of South Australia’s 900,000 electricity customers.

South Australia has more than 270,000 customers with solar systems capable of generating about 1.5GW of energy. Solar in the state can at times account for 70% of all generation.

“We’re having to move quickly in balancing support for the fast-growing number of solar customers, with the need to support the Australian Energy Market Operator (AEMO) and the SA Government on broader network security of supply issues,” said SA Power Networks manager corporate affairs Paul Roberts.

“SA Power Networks, with welcome support from the State Government, is investing in the rapid deployment of new voltage control measures in our larger substations … this will help us better regulate voltage levels throughout the day and year.”

Keep the volts down

During periods of high solar export in the middle of the day, the network will be able to “keep the volts down” to ensure customers can continue to export surplus PV to the grid.

The voltage management upgrades have already been implemented at 40 sites, with the remaining 100 currently planned to be completed by early 2021.

Meanwhile, AEMO has raised concerns around the ability to manage system security in the event the interconnector to Victoria goes down, given the high volume of solar generation in South Australia.

The new voltage management capability provides SA Power Networks the ability to assist AEMO in managing supply/load issues on the national grid.

“AEMO has said it may need us to help, as a last resort, in the unlikely scenario that the interconnector goes down on a few days of the year that we experience ‘minimum demand’,” Roberts said. “We would do this by making small changes to voltage at targeted substations. Our trials have confirmed we can do this effectively and safely while maintaining ongoing electricity supply for customers.”

If it sounds as though the state will have a controlling hand in PV system owners’ electricity plants and the revenue they produce, Roberts emphasised the benefits for solar customers include “more intelligent voltage management equipment [that] will facilitate additional exports on other days”.

“This is one of a number of initiatives we are implementing that will mean we can double the amount of renewable energy the electricity distribution network can accommodate by 2025.”