CAISO Transmission Congestion & Reconductoring Opportunities

12-month analysis of Day-Ahead Market shadow prices (Apr 2025 - Mar 2026) | Data: CAISO OASIS PRC_NOMOGRAM

Constrained Transmission Elements — Ranked by Estimated Congestion Cost ($)

Rank by:
i
Estimated Congestion Cost — Assumptions
Formula: Est. Cost = Σ(Shadow Priceh) × Thermal Rating (MW) × 70%
When a constraint is binding, the flow on the line is at its operating limit — but operating limits are typically 60-80% of the thermal rating due to N-1 contingency margins, stability limits, and voltage constraints. We apply a 70% derating factor to the thermal rating as a midpoint estimate of actual constrained flow.
Thermal ratings by voltage class:
60-70 kV75-100 MW thermal→ 53-70 MW est. flow
115 kV250 MW thermal→ 175 MW est. flow
230 kV700 MW thermal→ 490 MW est. flow
500 kV2,000 MW thermal→ 1,400 MW est. flow
Validation:
Our Path 15 corridor estimate ($336M) falls between the TPP's 2034 modeled cost ($389M) and a pro-rated 2034 figure, providing reasonable confidence in these assumptions.
Caveats:
  • Actual line ratings vary by conductor type, ambient temperature, wind, and span length.
  • The 70% factor is a system-wide average; individual lines may be higher or lower.
  • Transformers use the higher-voltage-side rating as a proxy, which may overestimate.
  • Lines with unknown voltage (shown as "?") are excluded from this view.
  • For authoritative dollar figures, use CAISO TPP Table 4.6-1 (GridView production cost model).

Click a bar to see details

Genuinely overlooked — no intervention
Studied/acknowledged but deferred or rejected
Intervention approved
Not yet researched
Not applicable (500 kV / stability / transformer)
Full opacity = renewable-driven | Reduced = load/other