Staff Mechanical Engineer — Thermals, BESS

Enphase Energy•Austin, TX

3d•$100,000 - $151,000•Onsite

About The Position

As a Staff Mechanical Engineer — Thermals, you will drive thermal architecture, cooling strategy, and safety design for utility-scale Battery Energy Storage Systems (BESS), spanning outdoor cabinets and containerized platforms. You will design Chiller-based, liquid-cooled, air-cooled, and hybrid thermal systems that support multi-MWh energy storage installations operating in demanding outdoor environments. This role requires hands-on expertise in thermal system design, advanced simulation, and BESS safety compliance. You will work closely with inverter, mechanical, electrical, controls, systems, safety, and manufacturing teams to ensure thermal solutions meet performance, reliability, manufacturability, serviceability, compliance, and cost targets — delivering production-ready designs from concept through deployment while optimizing CAPEX and long-term OPEX.

Requirements

Bachelor's or Master's in Mechanical or Thermal Engineering with 8+ years of hands-on experience, including experience with utility-scale BESS thermal architectures.
Strong proficiency in thermal and CFD simulations — system-level and detailed analysis, including airflow and system-flow simulations and transient and steady-state thermal analysis using tools such as Icepak, Fluent, COMSOL, and FLACS.
Experience translating simulation results into production-ready, compliant designs, including analyses supporting NFPA 68 (deflagration venting) and NFPA 69 (explosion prevention).
Experience with arcing analysis, containment design with sensors, venting, pressure-relief mechanisms, and propagation-mitigation strategies.
Strong system-level understanding of PCS architectures, battery rooms, DC- vs. AC-coupled systems, and thermal coordination with BMS, EMS, and PCS derating logic.
Demonstrated capability designing for high-ambient (45–55 °C), high-altitude, corrosive environments, and long-duration (2–8+ hour) energy storage systems.
Experience with reliability-driven thermal design, including 15–25-year system-life targets, redundancy, fail-safe and degraded-mode operation, and OPEX-optimized cooling strategies.
Experience driving DFMEA, root-cause analysis, and corrective actions based on test data and field feedback.
Experience supporting supplier selection and technical design reviews, balancing performance, reliability, manufacturability, and cost (CAPEX/OPEX).
Working knowledge of global safety and compliance standards, including UL 9540/9540A, NFPA 855/68/69, and IEC standards, with experience supporting certification and AHJ interactions.
Technical leadership skills, with the ability to lead projects, influence design decisions, and mentor junior engineers.

Responsibilities

Drive thermal architecture, cooling strategy, and safety design for cabinet-level and containerized BESS platforms, from concept through production and field deployment.
Design Chiller-based, liquid-cooled, air-cooled, and hybrid thermal systems for power electronics — including heat exchangers, chillers, cooling plates, pumps, valves, manifolds, fans, ducting, and venting devices.
Apply first-principles thermal engineering to design efficient, reliable, and cost-effective cooling solutions.
Perform system-level and detailed thermal and CFD analysis, and translate results into production-ready, compliant designs.
Lead arcing analysis, containment design with sensors, venting, pressure-relief mechanisms, and propagation-mitigation strategies.
Drive DFMEA, root-cause analysis, and corrective actions based on test data and field feedback.
Support supplier selection and technical design reviews, balancing performance, reliability, manufacturability, and cost (CAPEX/OPEX).
Support certification efforts and AHJ interactions across global safety and compliance standards.
Provide technical guidance and mentor junior engineers.