Electrical Engineer III-Subject Matter Expert 

Build What’s Next with Castillo Engineering

At Castillo Engineering, you will design utility-scale solar and battery storage projects that are shaping the future of energy while accelerating your own career in the process. We’re looking for an Electrical Engineer III who thrives on meaningful project ownership, has strong communication skills, a commitment to excellence, and a passion for supporting clean‑energy projects in a process‑driven, collaborative environment.

Why You’ll Love Working Here

We are a fast-growing, mission-driven firm where engineers are trusted, supported, and given clear opportunities to advance. You will work in a collaborative environment that values mentorship, innovation, and professional growth, allowing you to develop your skills, make a visible impact, and build confidence as part of a close-knit team.

Position Overview

The Electrical Engineer III-Subject Matter Expert (SME) — Electrical Engineering leads and provides expert-level oversight for PV and BESS electrical engineering across Castillo Engineering's Utility Scale project portfolio.  

This individual will serve as the Engineer of Record (EOR) for applicable projects, guide cross-functional teams from feasibility through commissioning, and ensure all deliverables meet technical, contractual, and regulatory requirements. A strong background in EPC (Engineering, Procurement & Construction) and/or EOR environments within utility-scale renewables is required. 

What You’ll Do

PV & BESS System Design & Engineering 

• 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: 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. 

EPC Project Delivery & EOR Responsibilities 

• Serve as 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. 
• Development of 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. 

Technical Leadership & Quality 

• 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. 

Client Engagement & Business Development 

• 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. 

What You Bring

• 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 preferred

Work Environment & Benefits

• This role has an onsite or remote work arrangement
• Competitive salary and performance-based bonuses
• Health, dental, and vision insurance (if applicable)
• Paid time off, company holidays, and professional growth opportunities
• Supportive culture committed to mentorship, innovation, and continuous improvement

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