Negative-price time share: method

What is measured

Sum the duration of valid TRADE intervals with RRP strictly below zero, divided by the duration of all valid TRADE intervals. Zero prices are excluded from the numerator. The result measures time, not electricity volume.

Coverage and timing

This snapshot covers Oct 2025 through Sept 2026 for NSW1, QLD1, VIC1, SA1 and TAS1. NSW1 includes the ACT. Western Australia, the Northern Territory and the historical Snowy region are excluded.

All intervals in this snapshot are five minutes. Settlement moved from thirty-minute trading prices to five-minute prices on 1 October 2021. Any future earlier history must use the applicable thirty-minute TRADE prices, rather than substituting five-minute dispatch prices.

Dates follow fixed AEST (UTC+10), without daylight saving. Source timestamps label interval endings; midnight at the start of the following month closes the preceding month. Daily assignment subtracts one interval from the ending timestamp.

Verification and provenance

Every one of the 60 region-month files is fetched from AEMO’s public aggregated price-and-demand dataset. Missing timestamps, duplicate timestamps, wrong regions, wrong interval lengths and non-finite prices block publication. No missing price is replaced by zero. Each file has a recorded URL, retrieval time and SHA-256 of the decompressed original bytes.

For all 60 files, the arithmetic interval-price mean is reconciled to the site’s published AEMO AVGRRP history within 0.005001 AUD/MWh, consistent with two-decimal source rounding. A separate offline verification independently counts negative prices and checks daily/monthly totals. The complete dataset is published only after all files pass.

Aggregation and interpretation

Monthly shares use actual month lengths. The regional 12-month share is total negative minutes divided by total valid minutes, not an unweighted mean of monthly percentages. There is no synthetic national average.

Negative time share is not generation capture price, curtailment, energy-weighted exposure, generator profitability, battery revenue or a PPA settlement. It cannot by itself identify why prices went negative. No SCADA or generation-output data is used.

Updates and article versions

This indicator is an offline verified snapshot. It is not refreshed by the monthly-price Cron, and daily detail does not mean live daily updates. Future source revisions require a reviewed rebuild. Existing articles keep their publication-time charts and conclusions.

Official dataset page · AEMO copyright permissions · method negative-time-v1.