​In May 2026, grid-scale battery revenues in the Wholesale Electricity Market rose 43% month-on-month to $40k/MW/year. The increase came as daily price spreads widened, with the 2-hour spread rising 35% to $97/MWh from $72/MWh in April.

Despite this, the merchant component of revenue remained below zero for the second consecutive month. Energy revenue was -$12k/MW/year, partly offset by FCESS, but total revenues still relied on RCM payments to finish positive. May also recorded no negative prices, leaving batteries with no opportunities to earn whilst charging.

​Neoen’s Collie units recorded positive merchant returns, while Synergy’s fleet continued to lose money on energy. The difference reflects how each asset operated through a month with higher average prices and no negative-price charging intervals.

This article reviews WEM battery revenues for May 2026, including asset-level merchant performance, market conditions, fleet growth and contracted revenue. Read last month's article here.

​Executive summary

• WEM total battery revenues rose 43% month-on-month to $40k/MW/year in May, supported by RCM revenue.
• The merchant component remained negative for the second consecutive month, partly offset by FCESS revenue.
• Energy revenue alone was -$12k/MW/year, marking the third month of losses. With no negative-price hours, batteries had fewer opportunities to earn while charging.
• ​Four of the six operational batteries recorded merchant losses, led by Kwinana 1 at -$48k/MW/year. Several Synergy assets continued to charge above their average discharge price.

​Market conditions improved, but merchant returns stayed negative

Most market conditions improved between April and May. Peak operational demand rose to 3.1 GW from 2.9GW, average energy prices increased to $116/MWh, and daily price spreads widened across every duration.