The 2026 US battery storage market isn't a procurement problem anymore — it's an engineering one. With 890 GW sitting in the interconnection queue, FEOC compliance thresholds reshaping every BOM, and tariff-driven cost shocks of up to 69%, the developers and EPCs who win will be those who treat chemistry-agnostic design, MACR documentation, and value engineering as core competencies — not afterthoughts.