Principal BESS Engineer - Procurement & Performance, Energy

Job Description

As a Principal BESS Engineer, you will lead technical and commercial advisory services for utility-scale battery energy storage systems across development, procurement, contracting, delivery and operation. The role is particularly focused on Owner's Engineer and procurement engagements, where clients need clear advice on how a BESS should be sized, specified, evaluated and contracted to achieve its intended duty over its operating life. You will bring the technical depth to understand the system and the commercial judgement to translate that understanding into bankable requirements, meaningful bid comparisons and practical risk allocation.

You will work with clients to define the duty profile and performance basis for a project, develop Principal's requirements and technical schedules, assess OEM and integrator proposals, support tender evaluations and negotiate key performance and warranty provisions. This includes net power and usable energy, state-of-charge operating windows, round-trip efficiency, auxiliary consumption, availability, degradation, cycling and throughput, augmentation, response performance, reactive-power capability, environmental derating, warranties, acceptance tests and long-term service obligations. You will also support detailed design reviews, factory and site testing, commissioning and performance verification.

The common thread is being able to connect technology, contracts and lifecycle value. You will identify where apparently attractive offers rely on different assumptions, exclusions or operating limits, explain the consequences clearly, and help clients make decisions that remain robust after contract award. The role will suit a BESS specialist who is equally comfortable interrogating a technical proposal, leading a commercial discussion and coordinating the wider electrical, civil, fire, grid and operational interfaces.

How you’ll make a difference:

• Lead BESS Owner's Engineer and technical advisory engagements across feasibility, procurement, contracting, design, construction, commissioning and operation.
• Establish the BESS sizing and performance basis using the intended dispatch duty, grid requirements, site climate, operating strategy, reliability requirements and lifecycle objectives.
• Prepare and review Principal's requirements, technical schedules and guarantees covering net power, usable energy, round-trip efficiency, availability, auxiliary consumption, degradation, augmentation, throughput, response performance and reactive-power capability.
• Lead tender evaluations and normalise competing offers by interrogating assumptions, exclusions, operating limits, warranted curves, design margins, augmentation strategies, lifecycle costs and technical risks.
• Support contract negotiations on performance guarantees, test and acceptance methods, warranties, liquidated damages and remedies, scope interfaces, long-term service obligations, operations and maintenance, and augmentation responsibilities.
• Review BESS architecture and interfaces across cells, modules, racks, containers, battery management systems, energy management or plant control systems, power conversion systems, medium-voltage systems, thermal management, fire safety and the grid connection; coordinate specialists and mentor team members.

Qualifications

To be successful in this role, you will be an experienced BESS engineer or technical advisor with a demonstrated record in utility-scale battery projects and a strong understanding of both technical performance and commercial delivery. You may have developed this experience with an owner, developer, OEM, system integrator, EPC contractor, lender, investor or engineering consultancy.

You will be known for your ability to move confidently between system sizing, technical specifications, vendor proposals and contract schedules. You will understand that BESS offers cannot be compared reliably without aligning duty, system boundaries, ambient conditions, degradation assumptions, augmentation strategy, warranty limits, test methods and the definition of net performance. Experience supporting competitive procurements and contract negotiations will be central to success in this role.

You will know your way around a BESS project, from cells and racks through battery management systems, thermal management, power conversion systems, energy management or plant control systems, medium-voltage systems and the grid connection. You will understand how design, safety, site conditions, operating strategy and contractual obligations interact over the project life. One of your strengths will be knowing where detailed specialist input is required and coordinating the right technical and commercial contributors to reach a defensible client recommendation.

The following qualifications and experience are highly desired, but if you don’t tick all the boxes, you could still be a perfect fit for this role. Please apply, all applications will be considered.

The qualities that help you thrive:

• Significant experience (8+ years) in the energy sector, including substantial hands-on experience with utility-scale BESS projects across development, procurement, delivery or operation.
• A background and experience of working in either / or a combination of consulting, developer, OEM, integrator or EPC industries.
• Strong capability in BESS sizing and operating-duty definition, including power and energy requirements, AC and DC boundaries, state-of-charge windows, duration, C-rate, cycling, throughput, degradation and augmentation.
• Detailed understanding of BESS performance criteria and guarantees, including net power, usable energy, round-trip efficiency, auxiliary consumption, availability, response, thermal derating, degradation, warranty limits and acceptance testing.
• Demonstrated experience preparing or reviewing procurement documentation, evaluating and normalising bids, undertaking technical due diligence, assessing departures and supporting commercial negotiations.
• Sound understanding of BESS technology and interfaces across cells, modules and racks, battery management systems, power conversion systems, energy management or plant control systems, medium-voltage balance of plant, grid connection, thermal management and fire safety.
• Experience with factory acceptance testing, site acceptance testing, commissioning, capacity or efficiency testing, and verification of contractual performance requirements is highly regarded.
• Commercial acumen and the ability to assess lifecycle value, risk allocation, warranties, performance remedies, long-term service agreements, operations and maintenance obligations, and augmentation strategy.
• Strong client engagement and communication skills, with the ability to advise, influence and build trusted relationships across technical, procurement, commercial and executive teams.
• Either registered, or working towards professional registration, on the National Engineering Register in Australia (such as RPEV or RPEQ), ideally supported by Chartered Professional Engineer (CPEng) status or equivalent international accreditation.
• A bachelor degree in electrical engineering, power systems or another engineering discipline relevant to battery energy storage systems.

Additional Information

Why you’ll love working with us

• Flexible work arrangements available, aligned with the market and client facing role requirements
• Purchase up to 6 weeks additional annual leave per year 
• Volunteer and representation leave
• Flex public holidays – swap Easter or other holidays for ones that suit you better

Ready to push the limits of what’s possible?

We welcome applications from individuals of all backgrounds, including those with disabilities, additional health or mental health needs, and/or neurodiverse conditions. If you require any adjustments during the hiring process, please let us know.

Applications are reviewed as they come in, and the role may close earlier than expected, so if this opportunity sounds like you, we encourage you to apply as soon as possible.

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AECOM acknowledges the Traditional Owners and Custodians of the lands on which we, our clients and our communities live and work around Australia. We pay our respects to their cultures and to their Elders — past, present, and emerging. We are committed to connecting to Country in our work through meaningful engagement with First Nations peoples and businesses.  Find out more about our Australian Reconciliation Action Plan here: https://aecom.com/au/our-vision-for-reconciliation/.

About AECOM

AECOM is the world’s trusted infrastructure consulting firm, delivering professional services throughout the project lifecycle – from advisory, planning, design and engineering to program and construction management. On projects spanning transportation, buildings, water, new energy and the environment, our public- and private-sector clients trust us to solve their most complex challenges. Our teams are driven by a common purpose to deliver a better world through our unrivaled technical and digital expertise, a culture of equity, diversity and inclusion, and a commitment to environmental, social and governance priorities. AECOM is a Fortune 500 firm and its Professional Services business had revenue of $16.1 billion in fiscal year 2025. See how we are delivering sustainable legacies for generations to come at aecom.com and @AECOM.

Freedom to Grow in a World of Opportunity 

You will have the flexibility you need to do your best work with hybrid work options. Whether you’re working from an AECOM office, remote location or at a client site, you will be working in a dynamic environment where your integrity, entrepreneurial spirit and pioneering mindset are championed.

You will help us foster a culture of equity, diversity and inclusion – a safe and respectful workplace, where we invite everyone to bring their whole selves to work using their unique talents, backgrounds and expertise to create transformational outcomes for our clients.

AECOM provides a wide array of compensation and benefits programs to meet the diverse needs of our employees and their families. We also provide a robust global well-being program. We’re the world’s trusted global infrastructure firm, and we’re in this together – your growth and success are ours too.

Join us, and you’ll get all the benefits of being a part of a global, publicly traded firm – access to industry-leading technology and thinking and transformational work with big impact and work flexibility. As an Equal Opportunity Employer, we believe in each person’s potential, and we’ll help you reach yours.