Hornsdale Power Reserve is a grid-connected energy storage system co-located with the Hornsdale Wind Farm in the Mid North region of South Australia. It is promoted as the largestlithium-ion battery in the world. During 2017 Tesla, Inc. won the contract and built the Hornsdale Power Reserve, for a capital cost of A$90 million, leading to the colloquial Tesla big battery name. In November 2019, Neoen confirmed that it was increasing capacity by a further 50MW/64.5MWh to a combined 185 MWh. The increased storage capacity was installed by March 23, 2020, and the increased power will follow later in the year.
Construction
South Australia received 90 proposals and considered 5 projects to build a grid-connected battery to increase grid stability under adverse weather events. Gas generators are uneconomic for providing grid stability. Elon Musk placed a wager that the battery would be completed within "100 days from contract signature", otherwise the battery would be free. Tesla had already begun construction, and some units were already operational by 29 September 2017, the time the grid contract was signed. The battery construction was completed and testing began on 25 November 2017. It was connected to the grid on 1 December 2017. The days between grid contract and completion easily beat Musk's wager of "100 days from contract signature", which started when a grid connection agreement was signed with ElectraNet on 29 September 2017, days after Musk's offer on 10 March. Samsung 21700-size cells are used. In November 2019, Neoen announced that it would increase the battery capacity by 50%. The expansion would cost, funded by from the state government, from ARENA and up to in cheap loans through the Clean Energy Finance Corporation.
Operation
It is owned and operated by Neoen, with the state government having the right to call on the stored power under certain circumstances. It provides a total of of storage capable of discharge at into the power grid, which is contractually divided into two parts:
30 MW for 3 hours is used by Neoen for load management to store energy when prices are low and sell it when demand is high.
On 14 December 2017, at 1:58:59 am, the HPR reacted when unit A3 at Loy Yang Power Station tripped. 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. This synchronverter reaction is a built-in feature, but had not previously been effectively demonstrated. During two days in January 2018 when the wholesale spot price for electricity in South Australia rose due to hot weather, the battery made its owners an estimated as they sold power from the battery to the grid for a price of around /MWh. Based on the first six months of operation, the reserve is estimated to earn about per year. After six months of operation, the Hornsdale Power Reserve was responsible for 55% of frequency control and ancillary services in South Australia. By the end of 2018, it was estimated that the Power Reserve had saved in costs, mostly in eliminating the need for a fuel-powered 35 MW Frequency Control Ancillary Service. The battery usually arbitrages 30 MW or less, but in May 2019 began charging and discharging at around 80 MW and for longer than usual, increasing wind power production by reducing.
