A weekly monitor of Japan's power markets for battery operators
Every week we summarise Japan's balancing market (EPRX), the JEPX day-ahead spot market and imbalance prices, using the same definitions and the same charts. Built on hands-on experience in power system operation and grid-scale battery development, the report turns public data into inputs for next week's bidding.
What you get
- Same definitions and charts every week: Week-on-week changes are directly comparable.
- All 9 areas, all products: The balancing market is covered for Primary, Secondary I/II, Tertiary I/II and Compound, by area and by wide-area procurement block.
- Battery bidding patterns compared every week: Net revenue of five bidding patterns is estimated with the same model for a virtual 2 MW / 8 MWh battery.
- Inputs for next week's bidding: Reference bid prices, thermal outages, and interconnector capacity reductions due to planned work.
- Japanese and English editions: The same content is issued in both languages.
Contents (38 pages, as of September 2026)
| Section | Pages | What it covers |
|---|---|---|
| Summary & review | 2 | Weekly summary of three markets (balancing, JEPX spot, imbalance); review of the best bids by area |
| 1. Balancing market (EPRX) | 7 | Awarded prices by area × product, bid ratio × price by wide-area block, Tertiary II spikes and under-subscription, cap ratios, area × hour prices |
| 2. JEPX day-ahead spot | 4 | Area prices, TB2/TB4 spreads, comparison of ways to choose charge and discharge hours, arbitrage net including loss cost |
| 3. Imbalance price | 5 | Shortage and surplus prices relative to spot, ratio trend, relation to the spot level, distribution, hour × area |
| 4. Battery bidding | 9 | kWh activation share, comparison of bidding patterns, how bid prices are set and reference bid prices, net revenue and capture rate, 8-week and cumulative results |
| 5. This week's bidding | 3 | Thermal outages, interconnector operating capacity, points to watch (ΔkW reference prices, kWh price, Tertiary II, JEPX, imbalance) |
| Definitions, sources, disclaimer | 2 | Definitions of indicators, model assumptions, data sources |
Plus a cover and section dividers (6 pages).
Sample (digest edition)
A 5-page digest of the issue for the week of September 19 to 25, 2026 is available.
Delivery
| Item | Details |
|---|---|
| Frequency | Weekly |
| Coverage | Market results of the previous week (Saturday to Friday) and information for next week's bidding |
| Format | |
| Languages | Japanese and English |
| Pricing | Available on request, depending on how you plan to use the report. |
Who it is for
- Operators and aggregators running or planning grid-scale batteries in Japan
- Teams in charge of bidding in the balancing market and JEPX
- Investors looking at battery storage projects in Japan
The report is our analysis of public information and does not guarantee future market developments or revenues. Battery revenues are estimates from a simplified model.