Traditionally, what happens during planned maintenance or system faults is that the Australian Energy Market Operator asks energy companies to contribute some of their network services, known as FCAS (frequency control and ancillary services). On January 14, it asked for 35MW. The major players -- AGL, Origin and Engie -- could only find 30MW of "low-priced" capacity (despite having more than 400MW available), so prices were set to go into orbit just as they had on 10 other occasions in the past 12 months. During these events prices reached AU$14,000/MW, with generators charging up to $7 million a day for a service that usually costs one-tenth of that.

Not this time, though, as the Tesla big battery rode in on a white horse and bid into the market, keeping prices down to around $270/MW. Experts say Tesla's role probably saved around $3 million or more -- good news for market players and consumers alike. According to Powershop Australia CEO Ed McManus, the Tesla big battery is already having a "phenomenal" impact. In this week's RenewEconomy's Energy Insider podcast, he said that January 14's events "plays into the thinking of new players looking to come into South Australia to challenge the incumbents", and that it's been a "very, very significant development for generation investment and generation competition" in the area. Tesla's not done turning the tide down under yet, either, as it this week announced further plans to create the largest-ever "virtual power plant" in the Australian state.