JEPX Pulse
Japan Power Market Intelligence

Primer on the Japanese power market: JEPX spot and intraday trading, 9 price areas, FIT and FIP, non-fossil certificates, curtailment rules, the capacity market, the EPRX balancing market and battery storage.

Market primer · trading rules · how to use JEPX Pulse

Japan power market guide

Japanese power market & trading rules

JEPX spot/intraday · FIT/FIP · certificates · curtailment · capacity & balancing · BESS

  • 48 half-hourly delivery slots (コマ); slot 1 = 00:00–00:30. Single-price blind auction, gate closure 10:00 JST the day before delivery.
  • System price is the unconstrained nationwide clearing price. When an interconnector is congested the market splits into area prices (エリアプライス) for the 9 areas. Splitting is now the norm, not the exception: in Apr–Jun 2026 all nine areas shared one price in only ~2% of half-hours and the western block (Chubu→Kyushu) cleared as one in ~6%. The Chubu–Kansai boundary (the 60 Hz side of the Kansai–Chubu tie, 64% of half-hours split — distinct from the Tokyo–Chubu frequency converters (FC) and from 関門, the Chugoku–Kyushu link) and Kansai–Shikoku (65%) split most often; Hokuriku–Kansai (~2%) are near-perfectly coupled. Live pair-by-pair figures: Volatility & Spreads → "split %" matrix.
  • Price floor ¥0.01/kWh (renewable oversupply; a strong signal of curtailment), ceiling ¥999. Kyushu, Shikoku and Hokkaido see the most floor hours in spring.
  • Volumes: ~30–40% of Japan's demand clears on spot; sell/buy bid curves are published daily.

  • Since 1 October 2026 intraday trading is API-only: orders go through the member API, from the member's own system or through one of the 13 trading-system providers JEPX lists (a direct dedicated line costs ¥500k to install plus ¥250k/month) — JEPX's own trading screen is gone. Trading still opens at 17:00 D-1 and closes one hour before delivery; the fee is ¥100/MWh.
  • Members see the order book in five area groups: Hokkaido / Tohoku–Tokyo / Chubu–Hokuriku–Kansai / Chugoku–Shikoku / Kyushu. The regulator chose groups rather than nine areas so that individual utilities' marginal costs can't be inferred, and members may not share this data outside the membership. The public data (the summary file this site uses) remains national: one weighted-average price and volume per half-hour. JEPX Pulse's area intraday figures are therefore the national intraday spread applied to each area's day-ahead schedule — a derived series, labelled as such everywhere, that cannot show splits between groups.
  • 1 October 2026 is treated as a series break: intraday and imbalance analytics have a pre / post toggle and the two periods are never averaged together; an early-days caveat shows while fewer than 30 post-change days exist. Read the full explainer: Japan's new intraday market (Oct 2026).
  • Other JEPX products: forward (先渡) market, non-fossil certificate auctions (see Certificates) and the baseload market (ベースロード市場) auctions for new retailers.

  • FIT: fixed tariff for 20 years (10 for small rooftop); the utility/TSO takes the power. No market exposure; curtailment compensated only under old 30-day rules.
  • FIP (since FY2022, mandatory for ≥250 kW solar and large wind): generator sells to market/PPA and receives a premium = 基準価格 − 参照価格. 参照価格 is a monthly area-average market price (with imbalance cost adjustments) — this app approximates it with the monthly area spot average.
  • FIP generators bear imbalance and capture-price risk but can add storage (co-located BESS) to shift output; 基準価格 for big solar is set by auction (入札).
  • Non-fossil value from FIT plants belongs to the state (sold as FIT certificates); FIP/non-FIT generators keep it (非FIT証書).

  • Two JEPX markets: 再エネ価値取引市場 (FIT certificates, multi-price auction, ¥0.4–4.0 band; buyers include RE100 corporates) and 高度化法義務達成市場 (non-FIT, single-price, ¥0.6–1.3 band; retailers buy to meet the 44% non-fossil obligation by 2030).
  • Certificates are tracked (トラッキング) so buyers can claim specific sources. Four auctions per fiscal year. "Bundled" corporate PPAs deliver power + certificate together — see the Bundled indicator in the Certificates tab.

  • Priority order (優先給電ルール): thermal down → pumped storage/battery charging → interconnector export → biomass → solar & wind curtailment → hydro/nuclear/geothermal last.
  • Kyushu curtails most (since 2018), followed by Chugoku, Shikoku, Tohoku, Hokkaido, Chubu. Rules: 30-day/360-hour/無制限無補償 depending on connection vintage; online (オンライン) control is being mandated.
  • Non-firm connection (ノンファーム型接続) on the trunk grid; OCCTO's Master Plan targets HVDC links (Hokkaido–Tokyo) to relieve congestion. Interconnector limits drive area price spreads shown in the Volatility tab.

  • OCCTO runs a nationwide capacity market (main auction 4 years ahead, additional auctions 1 year ahead). Retailers pay 容量拠出金; generators with contracts receive 容量確保契約金 — BESS and pumped hydro can participate; the long-term decarbonised power auction (長期脱炭素電源オークション) gives 20-year revenues to new BESS, hydrogen, nuclear.
  • 需給調整市場 (balancing-capacity market, run by EPRX since FY2021) procures reserves as ΔkW capacity by product: 一次調整力 (primary, ≤10 s), 二次調整力①② (secondary, ≤5 min), 三次調整力① (tertiary, ≤15 min) and 三次調整力② (FIT forecast-error reserve, ≤45 min), plus the 複合商品 bundle. Since 14 March 2026 every product trades day-ahead in 30-minute blocks (before: weekly, 3-hour blocks); ΔkW price caps for 一次 / 複合 stepped 19.51 → 15 → ¥10/ΔkW·30 min (Sept 2026) with a further step to ¥7.21 planned. TSOs regularly fall short of the requested volume in some areas — the Balancing page shows shortfall rates and cleared prices per area × product, and the BESS calculator can stack ΔkW revenue on arbitrage.

  • Grid-scale BESS boomed after the FY2023 subsidy rounds; standalone batteries can register as 発電事業者 and trade on JEPX, the balancing market and the capacity market.
  • Typical merchant case: 1 cycle/day arbitrage on the midday trough → evening peak (¥8–15 spread), plus balancing revenue. Degradation ~2–3%/yr, augmentation at ~70–80% SOH.
  • Co-located BESS with FIP solar can charge from curtailed/low-price output and discharge into the evening ramp without grid charging restrictions on FIP premium.

Understanding this platform

Data feeds, metric definitions, model assumptions

  • JEPX spot & intraday CSV (all 48 slots, 9 area prices, volumes) — fetched every hour, current + previous fiscal year.
  • OCCTO imbalance price publication (インバランス料金単価, 9 areas, 30-minute surplus/shortage prices, latest revision per month, 14 months).
  • TSO area supply-demand actuals (エリア需給実績, OCCTO-standard format) for all 9 TSOs — demand, nuclear, thermal, hydro, solar/wind actuals and curtailment volumes, pumped storage, batteries, interconnectors.
  • OCCTO 系統情報サービス interconnector flows (連系線潮流実績): 5-minute actual flow, operating capacity (運用容量), margin, planned flow and ATC (空容量) for all tie-lines, aggregated to 30-minute slots; 180 days of history, new days appear the morning after delivery.
  • OCCTO forward ATC (連系線空容量 翌々日～当日): three snapshots per link and delivery day — 翌々日 (D-2 15:00, the capacity offered to the JEPX spot auction), 翌日 (D-1 16:50, planned flow after spot results and remaining ATC for the intraday market) and 当日 (same-day updates) — with OCCTO's capacity-determining factor (運用容量決定要因). Refreshed hourly; 180 days of D-2/D-1 history for the signal hit-rate.
  • JEPX non-fossil certificate auction results, METI / OCCTO / JEPX notices for the Policy tab. Freshness of every feed is shown in the LIVE badge; "Refresh now" forces a fetch.

  • Capture price / rate: generation-weighted average price ÷ time-weighted average — <80% for solar signals heavy cannibalisation.
  • Midday depression: 10:00–14:00 average ÷ daily average. Floor hours: half-hours at ¥0.01. Split share: share of slots where an area decouples from system price.
  • Risk index (0–100) = 40% floor-price share + 40% curtailment ratio + 20% midday depression.
  • Spread matrix: mean row−column price difference — the basis risk of a cross-area PPA; the absolute view shows expected hedging cost.
  • Grid & Interconnectors: forward (順方向) follows OCCTO's convention for each link (from → to). Usable capacity = operating capacity − margin in the direction of flow; utilisation = |flow| ÷ usable; a half-hour is congested at ≥ 95%. Since April 2026 the Chubu–Hokuriku–Kansai AC loop is operated on area fences (中部・北陸・関西フェンス — the net flow across each area's boundary with the other two), so the three individual loop lines are shown only for pre-April history. A link at ≥ 95% in ≥ 95% of slots (the Anan–Kihoku HVDC, scheduled at its operating capacity) is flagged base flow and excluded from congestion KPIs. Explained by congestion = share of half-hours in which the two adjacent areas cleared at different JEPX prices while the link between them was congested — the share of the price split that is congestion-driven rather than a wider network split.
  • Congestion outlook (Grid page): two forward signals per link and day. Capacity reduced = spot usable (D-2 operating capacity − margin) ≥ 20% below the link's 30-day median actual usable capacity, with OCCTO's reason (熱容量(作業) = thermal limit during maintenance, 安定度 = stability, 電圧 = voltage, 周波数 = frequency). Planned at limit = remaining ATC ≤ 2% of usable in ≥ 2 hours of the D-1 plan — the day-ahead schedule already fills the link, so a price split is expected. Badges: Split likely (planned at limit), Watch (capacity reduced only), Clear, Awaiting plan (D-1 not yet published), Base flow. The reliability line reports how often each signal preceded actual ≥95% utilisation over the history window.

  • Generation shape uses the area's actual TSO output profile scaled to your capacity factor; revenue is annualised from the selected window (or a custom price curve).
  • Schemes: merchant, FIT (fixed), FIP (market + monthly premium), corporate PPA (fixed strike; CfD settlement shown).
  • BESS: perfect-foresight day-ahead arbitrage with charge-before-discharge; co-located BESS charges only from plant output.
  • Finance: unlevered pre-tax cash flows → project IRR, NPV, payback, LCOE/LCOS; with gearing → equity IRR and DSCR (annuity debt). Augmentation resets BESS SOH when it falls below the floor.
  • Intraday realisation stress: BESS day-ahead arbitrage is repriced with historical intraday (時間前) vs day-ahead spreads. JEPX publishes area prices only for day-ahead; public intraday data is nationwide, so area intraday prices are estimated as nationwide intraday average + (area DA − system DA), floored at ¥0.01. Levels: historical (each day's observed spread), P10 (discharge at P10 / charge at P90 spread — extreme downside), P50, P90 (extreme upside). The realisation ratio = stressed revenue ÷ day-ahead revenue. Area intraday prices are not published by JEPX; the area figures are the national spread applied to the area's day-ahead schedule (derived, labelled as such).
  • Imbalance settlement layer: official 30-minute area imbalance prices (published by the nine general TSOs on the インバランス料金情報公表ウェブサイト, imbalanceprices-cs.jp; from April 2022) joined to day-ahead prices. Price formation: the published price is max(調整力の限界的なkWh価格, 需給ひっ迫時補正); the 補正 follows the 補正料金算定インデックス — C below 3 %, D at 8 %, zero at ≥10 % — with C/D = ¥300/¥50 per kWh since 1 October 2026 (¥200/¥45 before). The site's monthly 算定根拠 files give the index, the marginal kWh price and the 補正 for every half-hour and area; the Scarcity page recomputes the 補正 from the index (reconciled to the published value) and shows what the ¥300/¥50 rule would have cost over any window — that rule-based figure is the calculator's ¥300-regime stress. 累積価格閾値制度 (from 1 October 2026): 30 half-hours with area spot ≥ ¥200 in the preceding 7 days cut the 補正 upper price to ¥100 until no half-hour ≥ ¥100 remains in the preceding 7 days. 1 October 2026 is a series break (pre / post toggle, never averaged). Per slot the adverse spread is the direction that hurts (shortage − DA when short, DA − surplus when long). Expected cost per kWh of error = adverse share × adverse spread + (1 − adverse share) × favourable spread, weighted by the plant's actual output shape. Inputs: forecast error (MAE as % of energy; single plant ~20–30%, aggregated portfolio ~8–12%), adverse share (default 70% — renewable errors are correlated with system imbalance; 50% = neutral), FIP balancing-cost allowance (METI バランシングコスト, indexed by delivery FY × FIP-start FY; FY2026 ¥1.70–2.00/kWh). BESS: plan deviation % of scheduled charge/discharge energy settled at the dispatch-slot expected spread. The finance panel can deduct the expected cost (and add the FIP allowance) before IRR. FIT plants carry no imbalance exposure.
  • Balancing market layer (EPRX): cleared results (取引実績, TSO-basis システム約定結果) for all seven products are downloaded conditionally every hour (HEAD → ETag) from EPRX; 速報値 (preliminary, published the day before delivery) is replaced by 確報値 (final) when EPRX publishes it. Shortfall = Σ max(requested − awarded, 0) ÷ Σ requested; average cleared price = mean of blocks with awards (¥/ΔkW·30 min); cap headroom uses the cap valid on the delivery date. Old (FY2025 weekly) and new (day-ahead from 2026-03-14) regimes are never averaged together. BESS ΔkW strategy: committed MW × cleared price × committed half-hours × award probability (default = 50% + 0.4 × shortfall/50%, from the trailing 90-day EPRX result for the area × product); committed power leaves the arbitrage dispatch during committed half-hours (idle half-hours first); the finance panel re-runs IRR with the price clipped at each cap step (15 / 10 / 7.21 ¥). Only ΔkW payments are counted — activation kWh, penalties and degradation from activation are ignored. Resource mix: EPRX's 電源種別別 files (nationwide, preliminary only, from Oct 2025) split awarded MW, bid counts and prices by 火力 / 水力・揚水 / 蓄電池 / VPP; the Balancing page shows the battery share of awarded ΔkW per product × month, the monthly stacked mix with battery vs thermal cleared prices, and the battery premium (battery − thermal awarded-MW-weighted average price). Forecast error: EPRX 三次② usage data (必要量 / 誤差実績 / 使用率) gives the official FIT forecast error per area; 1σ ÷ TSO solar + wind output over 90 days is the calculator's default forecast-error % when the field is left blank.
  • Portfolio dashboard: every saved scenario aggregated — combined revenue (basis = the case used for its IRR model), portfolio IRR from summed yearly cash flows, CAPEX-weighted IRR, equity-weighted equity IRR, P10 downside, imbalance cost, area exposure with HHI concentration, technology and scheme mix, revenue-weighted area risk index; one-click Excel export.
  • Chart cards: the PNG button on any panel renders that chart as a 1200×675 dark card (title, data date, jepx-pulse.com watermark) for LinkedIn or slides.
  • Save scenarios, compare up to 4, export Excel/PDF for investment committees.

  • AI briefing & weekly card now include the tie-lines that drove the latest day's area splits (hours, direction, split hours explained), imbalance spikes by area and the congestion outlook for today/tomorrow; the weekly card carries a Grid line (top congested link, hours, % of splits explained) and an imbalance-spike line. The daily briefing is generated automatically every morning at 07:30 JST (and on demand); generation continues server-side even if you close the page.
  • Congestion outlook card (Grid and AI Briefing pages): a 1200×675 PNG of the most informative day's tie-line outlook (tomorrow once its D-1 plan is out, otherwise today) — a one-sentence Claude-written "so what" hook, signal badge per link, spot usable capacity, D-1 plan-at-limit hours, OCCTO's reason, a mini grid map and the signal record — ready for a morning LinkedIn post; the hook is rewritten automatically when the signals change and can be rewritten on demand.
  • Briefing archive: every stored daily briefing can be opened from the archive list on the AI Briefing page (shareable as /briefing?date=YYYY-MM-DD); "Regenerate" on an archived date rewrites it from that day's data.
  • Alerts evaluate after every refresh: JEPX day-ahead rules (floor hours, spikes, thresholds, spreads), OCCTO imbalance rules (shortage price ≥ ¥X, shortage ≥ N× day-ahead, spike slots per day, daily average adverse spread), interconnector congestion hours per link, a forward congestion outlook rule that fires when a link is flagged Split likely (or Watch) for today, tomorrow or D+2, and EPRX balancing rules (area × product shortfall rate ≥ X%, max cleared ΔkW price ≥ X% of the cap); notifications appear in the bell.
  • Certificates: live auction feed with manual overrides; bundled green-power indicator = spot + certificate.
  • Policy: METI, OCCTO and JEPX notices with Claude English titles and implications; the weekly digest ranks them against your saved scenarios and alerts.
  • AI briefing answers with numbers from the loaded dataset only. All figures are for information — verify against primary sources before trading or investment decisions.
Sources: JEPX spot, intraday, 先渡 & 間接送電権 CSV · TSO area supply-demand actuals (エリア需給実績) · OCCTO imbalance, interconnector, 広域予備率 & capacity-market data · HJKS outages · EPRX · METI · EGC — attribution & terms · Japan's new intraday market (Oct 2026) · Prices in ¥/kWh · For information only, not investment advice.