[10] South Australia received 90 proposals and considered five projects to build a grid-connected battery to increase grid stability under adverse weather events.

[27] Phase one provided a total of 129 megawatt-hours (460 GJ) of storage capable of discharge at 100 megawatts (130,000 hp) into the power grid, which was contractually divided into several parts, covering energy arbitrage, frequency control and stabilisation services.

As its generators spun down over the next 30 seconds, the loss of its 560 MW of base power caused a dip in the system frequency.

By 1:59:19, the frequency had fallen to 49.8 Hz, and triggered HPR's response, injecting 7.3 MW into the grid and effectively helping to stabilise the system before the Gladstone Power Station was able to respond at 1:59:27.

[29] On 25 May 2021, HPR has reported a successful real-life test of its new “virtual machine mode” by demonstrating an inertial response from a small selection of trial inverters, following the grid disturbances created by events in Queensland.

After six months of operation, the Hornsdale Power Reserve was responsible for 55% of frequency control and ancillary services in South Australia.

[23][40] When the Heywood interconnector failed for 18 days in January 2020, HPR provided grid support while limiting power prices.

[42] By the end of 2018, it was estimated that the Power Reserve had saved A$40 million in costs, mostly in eliminating the need for a fuel-powered 35 MW Frequency Control Ancillary Service[43] also known as peaker plants.

[46] On September 23, 2021, the Australian Energy Regulator sued Neoen SA, saying the French firm's Tesla "Big Battery" in South Australia did not provide backup power during four months in 2019 for which it had received payment.