By AGILE Consulting Engineers, Solar PV and Battery Energy Storage Systems (BESS) specialists.
An Owner’s Engineer (OE) scope of work is easy to summarise in a single sentence and genuinely difficult to execute well. “Independent technical oversight from design to commissioning” covers dozens of distinct review activities, each with its own documents, its own failure modes, and its own point in the program where getting it wrong is either cheap or very expensive to fix. This is a walkthrough of what that scope actually looks like in practice on a utility-scale solar photovoltaic (PV) or battery energy storage system (BESS) project.
Table of Contents
- Design Review
- Specification and Procurement Review
- Contract and Technical Schedule Review
- Construction Monitoring and Quality Assurance
- Factory Acceptance Testing
- Site Acceptance Testing and Energisation
- Handover and Documentation
- What to Do Next
- FAQ
Design Review
Design review is where most OE engagements start, and it covers considerably more ground than checking a single-line diagram against an owner’s requirements document. A thorough review looks at the electrical design, including array layout, string sizing, inverter and power conversion system (PCS) selection, medium voltage collection network, and substation design, alongside the civil design covering foundations, access roads and drainage, and the structural design for racking and mounting systems. For a BESS, this extends to battery enclosure layout, fire detection and suppression concepts, thermal management, and the arrangement of the site relative to setback and separation requirements.
The point of this review is not to redesign the plant. It is to confirm that the design as proposed by the engineer of record actually meets the owner’s technical requirements, is internally consistent across disciplines, and reflects a defensible reading of the applicable Australian standards and network connection requirements. Design review at this stage also typically includes checking protection philosophy, earthing design, and the general approach to grid code compliance that will later be tested during connection studies with the network service provider and the Australian Energy Market Operator (AEMO).
Specification and Procurement Review
Once a design direction is set, the OE typically reviews the technical specifications that will go out to equipment suppliers and, in many project structures, to the Engineering, Procurement and Construction (EPC) contractor. This includes checking that performance guarantees are stated in terms that can actually be measured and verified later, that warranty terms match the design life assumed in the financial model, and that the specification does not quietly leave critical parameters, such as degradation curves for panels or batteries, or auxiliary power consumption, undefined.
Where the project structure allows it, the OE also reviews bid responses from prospective equipment suppliers or contractors, comparing technical claims against the specification and flagging where a bid appears to be offering a lower price by quietly relaxing a requirement. This is unglamorous work, but it is also where a large share of long-term underperformance risk gets either caught or missed.
Contract and Technical Schedule Review
Most utility-scale projects are delivered under some form of EPC contract, and the technical schedules attached to that contract are where design intent becomes a legally binding obligation. The OE’s role here is to review those schedules for consistency with the approved design, to check that performance testing methodologies are clearly defined rather than left to be agreed later, and to confirm that liquidated damages and performance guarantee mechanisms are tied to measurable, unambiguous criteria. A guarantee that cannot be objectively tested is not much of a guarantee.
This review typically extends to construction milestones and payment schedules, checking that payment is linked to genuinely completed and verified work rather than to self-certified progress claims from the contractor.
Construction Monitoring and Quality Assurance
Once construction begins, the OE’s role shifts from reviewing documents to monitoring physical work against those documents. This typically involves periodic or continuous site presence depending on project scale, review of the contractor’s quality assurance and quality control (QA/QC) documentation, attendance at key inspection and test points, and independent verification that installed work, such as pile depths, torque values, cable routing and earthing continuity, matches the approved design.
Non-conformance tracking is a core part of this activity. When installed work deviates from design or specification, the OE’s role is to document it clearly, assess its significance, and confirm it has been properly closed out rather than simply noted and left. A construction phase with disciplined non-conformance tracking tends to produce a plant that performs closer to its design intent and is easier to operate and maintain over its working life.
Factory Acceptance Testing
Factory Acceptance Testing (FAT) is conducted at the manufacturer’s facility before major equipment, such as inverters, PCS units, transformers and battery racks, is shipped to site. FAT is intended to confirm that equipment has been built and configured to specification and performs correctly under controlled conditions before it becomes far more expensive to rectify. An OE’s role in FAT is typically to review or witness testing, check the test procedure against the contractual requirements, and independently assess the resulting test report rather than accepting a supplier’s summary at face value.
This matters because the party conducting FAT, usually the equipment supplier or the EPC contractor’s nominated subcontractor, has a commercial interest in the test passing. Independent scrutiny at this point is one of the more cost-effective interventions available across the whole project, because catching a defect in a factory is materially cheaper than catching the same defect once the equipment is installed on site.
Site Acceptance Testing and Energisation
Site Acceptance Testing (SAT) verifies that the installed and interconnected plant performs as intended once it is energised in its actual site environment, generally measured at or near the point of connection to the network. This includes protection testing, communications and Supervisory Control and Data Acquisition (SCADA) verification, and staged performance testing against the acceptance criteria set out in the EPC contract. For a BESS, SAT typically also covers verification of battery management system (BMS) behaviour, thermal management performance, and response to dispatch instructions under representative operating conditions.
The OE’s role during SAT is again one of independent verification, reviewing test procedures before they run, witnessing key tests where practical, and confirming that results genuinely meet the contracted criteria rather than being presented in a way that obscures a marginal result. This is also typically where reliability or capacity testing begins, feeding into the substantial completion or provisional acceptance milestone under the EPC contract.
Handover and Documentation
The final stage of a typical OE checklist covers punch list closure, as-built documentation review, and technical handover to the operations and maintenance provider. This includes confirming that outstanding defects identified during construction and commissioning have actually been closed out, that operating and maintenance manuals reflect the as-built plant rather than an earlier design revision, and that spare parts, warranty documentation and test records are compiled in a form the operations team can actually use. A rushed or incomplete handover tends to resurface as operational friction well into the project’s working life.
What to Do Next
Working through this checklist properly takes discipline and time, and it is considerably easier to apply when an independent reviewer is embedded from the start rather than brought in to catch up midway through construction. We’ve helped project teams structure this kind of review across design, procurement and commissioning, and it is worth having that conversation before the design freeze rather than after it.
FAQ
Does an Owner’s Engineer redesign the project during design review?
No, the OE checks that the design meets the owner’s technical requirements and applicable standards, it does not replace or take over the role of the engineer of record.
What is the difference between FAT and SAT in this checklist?
FAT verifies equipment performance at the manufacturer’s facility before shipment, while SAT verifies the installed and interconnected plant’s performance on site, generally against acceptance criteria measured at or near the point of connection.
Why does contract and technical schedule review matter if the design has already been approved?
A design can be technically sound but poorly protected contractually if performance guarantees and testing methodologies in the technical schedules are vague or unmeasurable, which is why schedule review is treated as a distinct step.
What does non-conformance tracking actually involve during construction?
It involves documenting deviations from approved design or specification as they are found, assessing their significance, and independently confirming they have been properly closed out rather than simply noted.
Is site presence during construction always continuous?
It depends on project scale and risk profile, some projects warrant continuous OE presence while others are adequately served by periodic site visits combined with review of contractor QA/QC documentation.
What happens if handover documentation is incomplete?
Incomplete or inaccurate as-built documentation and operating manuals tend to create ongoing friction for the operations and maintenance team, which is why documentation review is treated as a distinct checklist item rather than an afterthought.
