JEPX Daily Briefing — Saturday 19 September 2026

1. Headline

System price averaged 16.84 (−0.34 d/d), with a benign national picture masking a sharp east–west split: Tokyo (東京) firmed to 22.26 (+1.31) while Tohoku (東北) slumped 4.48 to 12.16 and the entire western bloc from Hokuriku (北陸) to Kyushu (九州) settled at 12.37–12.38. No floor-price or spike intervals were recorded anywhere, and curtailment was zero across all areas on the latest (18 Sep) data, but a 10-yen Tokyo–west spread shows interconnector congestion, not scarcity, is setting the marginal price.

2. System & Area Prices

• System shape: trough 10.31 @ 12:00, peak 22.51 @ 18:30. Midday avg 10.59 vs evening avg 22.15 — an 11.56 intraday swing. Depression ratio 0.629.
• Trend: 16.84 sits below the 7-day (18.40) and 30-day (20.36) averages. Today's Saturday reading is a milder weekend dip than 5–6 Sep (14.49/13.25) or 12–13 Sep (12.47/14.29).
• Liquidity: 943.2 GWh traded; sell bids 1,611.1 GWh vs buy bids 1,175.5 GWh (~1.37× sell/buy) — a clearly long book.
• Tokyo: 22.26 avg (min 13.39, max 25.91), midday avg 20.80, depression 0.935 — essentially no solar dip. Spread vs system +5.42.
• Chubu (中部): 19.63 (−1.69). Midday 12.00 vs Tokyo's 20.80 (8.8 gap) → FC congestion midday; evening 22.73 and max 25.91 identical to Tokyo → coupled at peak.
• Tohoku: 12.16 (−4.48), min 9.44, max 20.33. Spread vs Tokyo −10.10 (vs 30d avg −5.06) — the Tohoku–Tokyo tie constrained, trapping northern supply.
• Hokkaido (北海道): 15.93 (+0.63) — 3.77 *above* Tohoku, reversing the 30d norm (Hokkaido −2.53 vs Tohoku). Flat profile (midday 15.25, evening 15.84, depression 0.958); coupled with Tohoku at 15.84 in the evening, split 95.8% of intervals.
• West (Hokuriku/Kansai (関西)/Chugoku (中国)/Shikoku (四国)/Kyushu): fully coupled at 12.37–12.38; min 8.10, midday 9.73, evening 17.79, max 18.71. Spread vs Tokyo −9.88/−9.89, nearly double the 30d Tokyo–Kyushu spread of 5.62.

3. Solar Cannibalisation & Curtailment

• Floor hours: 0.0 nationwide today; no 0.01 clears despite heavy midday oversupply in the west.
• Midday depression: most acute in Chubu (0.612) and system (0.629); west 0.786, Tohoku 0.781. Tokyo (0.935) and Hokkaido (0.958) largely immune.
• Curtailment (latest data): 0 MWh solar and wind in all areas on 18 Sep; Hokkaido (13 Sep) 9 MWh solar. Midday VRE shares 18 Sep: Tohoku 57.4%, Hokkaido 55.5% (13 Sep), Chubu 39.6%, Tokyo 25.2%, Kyushu 21.9%.
• 30-day solar capture rates: Tohoku 0.594 (10.52), Hokkaido 0.638 (9.28), Shikoku 0.769, Chugoku 0.827, Kyushu 0.851, Chubu 0.961, Hokuriku 0.989, Kansai 1.011, Tokyo 1.029 (23.17).
• 30-day curtailment: Kyushu 3.35 GWh solar (0.23%), Hokkaido 2.72 GWh solar + 1.24 GWh wind (0.88%), Tohoku 0.70 GWh solar (0.52%); zero elsewhere. Wind capture strong: Tohoku 0.969, Shikoku 1.143, Kansai 1.116.

4. Volatility & Spreads

• 30d dispersion: system CV 33.8% (std 6.88, p10 11.70 / p90 30.00). Shikoku (56.8%) and Kyushu (51.2%) are the most volatile, with 44.5 and 37.5 spike hours; Tokyo the calmest (27.0%, 3.0 spike hours). Western max 55.23 vs Hokkaido 47.50.
• Floor exposure 30d: Hokkaido 16.0 h and Shikoku 16.5 h (2.1% each); Chugoku/Kyushu 1.0 h.
• Today's realised shape spreads (evening − midday): system 11.56, Chubu 10.73, west 8.06, Tohoku 6.34, Tokyo just 1.93 — batteries in Chubu/west earn a 5×+ larger arbitrage than in Tokyo.
• Locational basis: today's Tokyo–west/Tohoku gap (~10) is roughly double the 30d average — a bad day for anyone with west/Tohoku generation settling against a Tokyo-indexed PPA.
• Peak/off-peak ratio 30d: Kansai 1.49, Hokuriku 1.48, Kyushu 1.41 vs Tohoku 0.98, Hokkaido 1.02 — northern areas offer no evening premium to recover midday losses.

5. Actionable Takeaways

• Price basis risk explicitly. With Tohoku/west vs Tokyo spreads hitting ~10 today against a 30d norm of 5–6, virtual PPAs settling in Tokyo but sourced from Tohoku or Kyushu need a basis collar or area-indexed settlement; Tohoku's 0.594 solar capture rate is the weakest in Japan.
• FIP generators in the west: lean into the evening. With midday at 9.73 and evening 17.79 (max 18.71), co-located storage or dispatch shifting captures an 8-yen spread; Chubu's 10.73 swing and 55.23 30d max make it the strongest storage business case with zero curtailment exposure.
• Tokyo remains the offtaker's clean play. Solar capture rate 1.029 on 30d, depression 0.935 today, no floor or curtailment history — corporate PPA