​In May 2026, grid-scale battery revenues in the Wholesale Electricity Market rose 30% month-on-month to $53k/MW/year. The increase came as daily price spreads widened, with the 2-hour spread rising 20% to $89/MWh from $74/MWh in April.

​The merchant component of revenue returned to positive territory at $8k/MW/year, the first positive merchant month since March. Energy revenue was $1k/MW/year, barely positive, with FCESS adding the remainder. Total revenues reached $53k/MW/year, supported by RCM payments. May also recorded no negative prices, leaving batteries without cheap charging windows.

Four of the six operational batteries recorded positive merchant returns. Only Collie Synergy 1 and Collie Synergy 2 recorded merchant losses. 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 30% month-on-month to $53k/MW/year in May, supported by RCM revenue.
• The merchant component returned to positive territory at $8k/MW/year, the first positive result since March.
• Energy revenue alone was $1k/MW/year. With no negative-price hours, batteries had fewer cheap charging opportunities but also avoided forced charging losses.
• Four of the six operational batteries recorded positive merchant revenue. Only Collie Synergy 1 (-$8k/MW/year) and Collie Synergy 2 (-$10k/MW/year) recorded merchant losses.

​Market conditions improved, and merchant revenues returned to positive territory

Most market conditions improved between April and May. Peak operational demand rose to 3.1 GW from 3.0 GW, average energy prices increased to $116/MWh, and daily price spreads widened across every duration.