Big batteries set new charging records, despite lack of price volatility

NSW set two new battery charging records on Saturday, May 2, but the more interesting point may be that this happened in a relatively calm market.

This was not a day of extreme NSW price volatility, with dispatch prices ranging from only -$1.10/MWh to $79/MWh across the day.

Even so, the NSW battery fleet charged at record levels through the late morning solar window, filled materially through the middle of the day, and then discharged steadily into the evening shoulder.

Records

– Battery charge share of consumption: 11.9 per cent at 10.05am, up +0.9 percentage points (+8.18%) on the previous record of 11.0 per cent reached on April 12, and 3.8 per cent ahead of its level a year ago.

– Battery charge: 1,240 MW at 10.50am, up 75 MW on the previous record of 1,165 MW, also reached on April 12, and 341 MW ahead of its levels a year ago.

A few observations

Across the day, NSW batteries charged around 4.47 gigawatt hours (GWh) at an average price of about $15.80/MWh, and discharged around 3.31 GWh at an average price of about $58.76/MWh.

That is a charge-to-discharge price spread of about $43/MWh, on a day when the full dispatch price range was only about $80/MWh.

The storage trace adds a second layer. NSW BDU (bi-directional unit) stored energy moved from a low of about 608 MWh at 06:45 to a high of about 4,353 MWh at 14:15, close to 87% of the visible storage capacity. That stored energy was then drawn down through the evening.

This was therefore not only a charging record. It was a visible example of the daily rhythm of battery storage becoming more established: charging into the solar trough, holding energy through the afternoon, and releasing it into the evening shoulder.

The open question is whether this daily rhythm is enough on its own. The day appears to have produced useful gross arbitrage value, but it was not a volatility windfall.

More likely, batteries are doing two things at once: earning routine margin from ordinary solar-shaped days, while remaining available for sharper price events that may still do much of the annual financial work.

That is not a criticism. It may be what disciplined battery operation looks like in a calmer market: use the ordinary days well, and stay available for the extraordinary ones.

The emerging NSW story is not just batteries chasing volatility. It is batteries settling into a daily rhythm between price spikes. More daytime abundance. More flexible absorption. More value in timing.