The BESS Senior Field Service Engineer (Sr. FSE) is responsible for providing expert field service on Battery Energy Storage Systems (BESS) and ancillary equipment from commissioning completion / installation through warranty and long‑term service support. This role interfaces with third‑party suppliers of major components (including inverters/PCS, transformers, HVAC) and operates as a technical lead supporting customers, subcontractors/authorized service providers, and internal field teams.