BNEF's December 2025 survey placed North American pack prices 44% above China's. IEA's Global EV Outlook 2026 measured 30%. Both are pack-level annual averages mixing applications, and both are purely geographic. They capture logistics and currency but not the compliance stack that determines whether a US BESS buyer can actually deploy the supply.
That stack has its own cost structure. Section 301 tariffs on non-EV lithium-ion batteries reached 25% on January 1, 2026, unaffected by the SCOTUS IEEPA ruling. Treasury's Notice 2026-15 made FEOC traceability operational for storage projects beginning construction this year, with MACR thresholds rising annually. NFPA 855's 2026 edition and UL 9540A 6th Edition escalated fire-test requirements. Lenders underwrite against the ITC, which FEOC failure eliminates.
Each layer adds cost, time, or disqualification risk independent of what cells clear at in Changsha. Proof requirements, not spot, determine the US usable-supply floor. H1 2026 tightened several of those requirements simultaneously, and the floor moved accordingly while China spot held flat.
What sits between China EXW and US deployable:
- 25% Section 301 tariff — effective Jan 1, 2026 on non-EV Li-ion (HTSUS 8507.60.0020); Section 122's additional 10% expires July 24 with no announced replacement
- FEOC/MACR traceability — 55% threshold for energy storage in 2026, rising annually; failure disqualifies the ITC (30–40% of project cost)
- UL 9540A + NFPA 855 — 6th Edition published March 2026; 3–12 months for full certification; no AHJ approval without it
- Warranty counterparty — lenders require creditworthy warranty backing; post-delivery sourcing from a restricted entity can trigger IRS credit recapture
- Financeability screen — projects with unresolved FEOC chains cannot close tax equity
The benchmarks (BNEF 44%, IEA 30%) capture rungs 1–2 at best. Rungs 3–5 carry real cost but show up nowhere in the published spread.