Japan’s Ministry of Economy, Trade and Industry convened the 24th meeting of its Simultaneous Market Study Group on June 29, 2026, advancing plans for the co-optimisation of energy (kWh) and balancing capacity (ΔkW).
The committee endorsed a specialist working group to test market-clearing feasibility and operational design during fiscal 2026. This was not a final decision to launch the market. Pricing, settlement, uplift payments and the participation rules for battery energy storage systems (BESS) and distributed energy resources (DER) remain under review.
SCUC and SCED to be tested
The technical study will assess Security-Constrained Unit Commitment (SCUC) and Security-Constrained Economic Dispatch (SCED), drawing on PJM, CAISO and ERCOT while reflecting Japan’s interconnector constraints, transmission losses, pumped hydro and growing renewable penetration.
The model will be tested under renewable-surplus, supply-scarcity and network-congestion scenarios. Initial findings are expected around January 2027 and will inform subsequent system requirements and detailed market design.
Intraday and near-real-time trading
METI will examine an intraday market with roughly three auctions and a near-real-time market operating either 24 or 48 times daily. Gate closure, continuous trading and settlement across successive markets remain unresolved.
BESS participation will require intertemporal optimisation of State of Charge (SoC), charging, discharging and operating limits. DER participation will depend on minimum bid sizes, aggregation rules and baseline methodologies.
For generators, retailers and aggregators, the reform could require more granular operating data, automated scheduling and stronger intraday trading capabilities. Developers and lenders must meanwhile assess projects under multiple scenarios, as implementation timing, bidding rules and penalties have not yet been decided.
Sources
24th Meeting of the Study Group on the Future of the Simultaneous Market
