Intraday Market Displays Bids by Area, Adjusted Imbalance Cap Rises to JPY 300/kWh

On October 1, the Japan Electric Power Exchange (JEPX) began displaying bid information by area in its intraday market. The screen for trading participants now shows bid information for the nine areas grouped into five zones, allowing participants to place bids that account for market splitting caused by interconnection constraints. The intraday market is open for trading from 17:00 on the day before delivery until one hour before each delivery slot begins on the day of delivery.

Previously, participants could not tell from the trading screen which area a sell order had been placed in, so buy orders sometimes failed to execute due to interconnection constraints, and several market participants had requested disclosure of this information. Because displaying all nine areas separately could make bidders identifiable, the information is grouped into five zones: (1) Hokkaido, (2) Tohoku and Tokyo, (3) Chubu, Hokuriku, and Kansai, (4) Chugoku and Shikoku, and (5) Kyushu. Buyers can now confirm whether sell orders that can supply their own area exist.

Alongside this change, the cap on the adjusted imbalance price applied during supply-demand tightness has been raised from JPY 200/kWh to JPY 300/kWh in FY2026. The adjusted imbalance price is a mechanism that raises the imbalance price during supply-demand tightness. The change reflects the tendency that intraday market bid prices did not rise significantly even when supply and demand were tight, so the price did little to encourage imbalance avoidance. At the same time, a cumulative price threshold (CPT) mechanism will be introduced, which lowers the imbalance price cap to JPY 100/kWh if spot market prices stay at JPY 200/kWh or higher for consecutive time slots.

🔍 Shulman Commentary:

The changes increase the cost of imbalances during tight supply-demand conditions, while limiting retailer exposure when high prices persist. At the same time, greater visibility of the location of intraday bids should help participants manage their positions more effectively before delivery, particularly when interconnection constraints lead to market splitting.

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