The Tesla big battery remains the most watched aspect of Australia’s National Electricity Market – apart from the spate of Lack of Reserve notices in the current heatwave – and on Wednesday for the first time it discharged at its maximum capacity.

The injection of 100MW into the grid from what is known to the market as the Hornsdale Power Reserve, occurred just before midday (NEM-time). It followed some charging overnight and a brief spurt of discharging and charging earlier in the morning.

For those looking for evidence of rhyme and reason in the various bursts of activity (i.e. taking advantage of price arbitrage), then it should be noted that this is still part of the shake-down for the new lithium-ion battery – the largest in the world at 100MW/129MWh.

Tesla and the plant owners and operators, French renewable energy developer Neoen, are still testing its range and potential, and seeing how it responds to real-world environment. The battery is located near Neoen’s Hornsdale wind farm, near Jamestown in South Australia.

The battery has already been called into active service on one occasion, a day before its official opening when it helped the grid ride through a big afternoon peak.

And, as we reported on Wednesday, it has also been providing network services through the multi-faceted FCAS (frequency control and ancillary services) market. See our story: What is the Tesla big battery selling: it is not just energy.

(Today’s graph courtesy of Dylan McConnell from the Melbourne Climate and Energy College).

P.S. The Australian Energy Market Operator has issued a spate of Lack of Reserve (LOR) notices in South Australia, Victoria and NSW in the past week, but all have been cancelled as the market responded by offering previously idle generation.

At the time of publication, one LOR notice remained open, in NSW, for Thursday afternoon as 40°C temperatures hit western Sydney and other parts of the state.