Key pricing in Western Australia’s electricity transition is increasingly being decided in the evening peak. The data below enables us to show an answer to the above question.
The 30-minute WA Wholesale Electricity Market (WEM) data for 10–21 August 2026 captures a period of heightened system stress while much of the coal fleet was unavailable (Figure 1). These are interval-level associations from a short period, not a dispatch model or a full-year causal estimate – but they reveal the price-setting dynamics that daily averages can obscure.
Daytime charging brings a large negative load, coincident with the solar peak. Battery discharge then rises sharply through the late-afternoon and evening transition, at precisely the time gas would otherwise have to fill more of the gap.
For now, coal and gas remain substantial, but batteries are visibly reshaping the residual demand they face. The plot shows a grid already operating as a dynamic mix of rooftop solar, utility solar, wind, batteries, coal and gas – and the WEM is no longer a system in which gas simply steps in to replace coal.
Figure 1: Western Australian WEM 30-minute electricity generation, and battery charging and dispatch by source, 10–21 August 202
