Electrical Engineer III/Subject Matter Expert

Purpose

The purpose of this position is to lead and provide expert-level oversight for PV and BESS electrical engineering across Castillo Engineering's Utility Scale project portfolio.

Responsibilities

• Lead and manage the electrical design of utility-scale, ground-mounted Solar PV and Battery Energy Storage Systems (BESS), including system architecture, DC/AC electrical layout, and integration with power generation, distribution, and control systems.
• Develop and review key deliverables such as single-line diagrams (SLDs), one-line development, battery sizing analyses, inverter and transformer selection, cable ampacity calculations, grounding and bonding designs, and protective relaying schemes.
• Develop interconnection diagrams for standalone, grid-connected, and hybrid PV/BESS systems including medium-voltage distribution and substation interfaces.
• Conduct and review power system studies including load flow, short-circuit, arc flash, protection coordination, and voltage drop analyses using ETAP, SKM, or equivalent tools.
• Review feasibility studies, site assessments, and energy storage system sizing analyses to evaluate project viability, identify technical requirements, and recommend optimal BESS configurations — including provisions for future capacity augmentation.
• Serve as the Engineer of Record (EOR) — stamp and seal electrical deliverables across applicable jurisdictions, with ability to obtain reciprocal PE licensure in multiple states.
• Manage electrical scope within EPC project structures, coordinating across engineering, procurement, and construction phases from early-stage feasibility through commercial operation date (COD).
• Oversee design development, contract reviews, system interconnection requirements, and performance modeling throughout the full project lifecycle.
• Collaborate with EPC partners, construction teams, and internal project managers to resolve technical issues, maintain schedule, and control scope.
• Develop technical specifications for BESS components (battery cabinets, inverters, transformers, switchgear, metering, and control systems).
• Provide engineering support for system testing, validation, and commissioning of PV and BESS systems, coordinating with stakeholders to ensure successful integration and performance validation.
• Serve as the technical authority and discipline lead for electrical engineering across PV and BESS projects.
• Develop and enforce discipline-specific design criteria, standards, and best practices for renewable energy projects.
• Oversee system modeling and simulation to optimize BESS performance, efficiency, and reliability — considering load profiles, grid requirements, and ancillary services.
• Stay current on solar PV and BESS technologies, grid integration advancements, energy management systems, and evolving regulatory requirements.
• Act as the client-facing technical representative for electrical scope discussions, design presentations, and project meetings.
• Identify and communicate project risks related to PV and BESS electrical systems, providing mitigation strategies and recommendations.
• Support proposals, scope development, and cost estimates for renewable energy engineering services.
• Participate in industry organizations and technical working groups to represent Castillo Engineering and build the firm's renewable energy presence.

Requirements

• Masters or bachelor's degree in electrical engineering from an ABET-accredited institution
• Active Professional Engineer (PE) license — with willingness and ability to obtain reciprocal licensure in multiple U.S. states
• Minimum 10 years of electrical engineering experience, with at least 5 years focused on utility-scale Solar PV and/or BESS projects
• Demonstrated EOR experience — ability to stamp and seal electrical engineering deliverables on utility-scale renewable projects
• Proven EPC project experience with a track record of managing scope across engineering, procurement, and construction phases
• In-depth expertise in PV system design including battery sizing, one-line development, site layout, inverter and transformer selection, cable ampacity calculations, grounding/bonding, and protective relaying
• Hands-on proficiency with power systems analysis tools: ETAP, SKM PowerTools, or equivalent
• Proficiency with Solar PV modeling software: PVsyst, or equivalent
• Strong knowledge of applicable codes and standards: NEC, NFPA 70E, IEEE, ANSI, and OSHA electrical regulations as applied to PV and BESS installations
• Experience with medium-voltage electrical systems and grid interconnection requirements
• Strong written and verbal communication skills with ability to present complex technical content to clients and non-technical stakeholders
• Experience with substation design, high-voltage systems (>34.5 kV), or microgrid design preferred
• Familiarity with BESS augmentation planning, state-of-charge management, and ancillary services design preferred
• Proficiency in AutoCAD preferred
• Prior experience in an engineering consulting or EPC firm environment preferred
• A mix of field engineering, EOR, owner's engineer (OE), and EPC experience in renewable energy is highly desirable