Senior Manager of BESS Engineering

One Energy Inc Chicago, Illinois, United States

One Energy’s mission is to make clean energy the #1 source of electricity for consumers and utilities. We develop solar energy and battery energy storage (BESS) projects across the United States in community solar, distributed generation, and large utility scale project segments.

Our diverse project pipeline, multiple locations across the US, and unique multidisciplined team sets us apart.

We are a dynamic and innovative renewable energy industry company committed to excellence, collaboration, and driving positive change in our industry.

The Sr. BESS Manager, owns One Energy's battery energy storage engineering function and is accountable for standing it up as a repeatable, institutional capability. This is a senior, hands‑on leadership role for an engineer who has not only designed DG and utility‑scale BESS systems but has carried multiple BESS projects through full construction and commissioning cycles. The role mirrors and integrates with OER's established PV processes, tools, and standards;

builds the BESS equivalents where they do not yet exist, and operates across Development, Preconstruction, Finance, and Engineering. Reporting to the VP of Engineering and directing future Associate Engineers, the position demands strong interdepartmental coordination, personal initiative, and the judgment to make sound decisions on equipment, cost, and layout designs.

• Define and maintain BESS design standards, templates, and workflows (SLDs, layouts, equipment specifications) and keep them current with the team's latest PV standards.
• Establish and enforce a workflow for tracking BESS status, tiering, and prioritization across all company strategies.
• Lead DG and utility‑scale BESS plant design; review and approve high‑voltage substation, medium‑voltage collection, and BESS plant drawing packages at each design stage.
• Lead design and modeling discussions across the engineering team and outside consultants.
• Lead BESS CAPEX methodology: match each commercial opportunity to equipment sizing, guarantees, and warranties, and develop equipment and EPC cost estimates.
• Drive equipment selection and pricing through collaboration with the Preconstruction Team
• Own relationships with key BESS integrators, equipment providers, and contractors.
• Maintain safety standards and keep all documentation current with the latest NFPA 855, NEC (including Article 706, Energy Storage Systems), NESC, and UL 9540 / UL 9540A requirements.
• Lead BESS RFP responses, coordinating internal resources and vendor‑provided technical details and assumptions, and reusing and escalating prior material for fast turnarounds.
• Provide feedback on System Impact and Feasibility Studies as needed.
• Serve as the bridge across Development, Preconstruction, Finance, and Engineering, handing off finalized equipment selection and quantities to Engineering for SLDs and layouts.
• Act as an extension of the Development team on community outreach, permitting, and strategic pipeline planning.

• Degree in electrical, mechanical, or a related engineering field.
• PE license, or a clear and near‑term path to licensure.
• 6+ years in professional engineering, construction, or land development, with a substantial and recent portion focused on battery energy storage.
• Demonstrated experience taking multiple DG and/or utility‑scale BESS projects through full construction and commissioning cycles.
• Direct experience selecting, sizing, and procuring BESS equipment across multiple OEMs and integrators.
• Strong familiarity of NEC (including Article 706), NESC, NFPA 855, and UL 9540 / UL 9540A as applied to energy storage systems.
• Experience…