What Is Independent Inspection? An Owner's Engineering Guide for Solar Investors
The party building the plant runs its own quality control; independent technical verification protecting the investor is a separate owner's engineering function.
A guide to independent inspection and owner’s engineering: what the service is, the difference between EPC QA/QC and independent technical verification, design–manufacturing–site–test checks, and technical participation in acceptance procedures.
| TECHNICAL REVIEW | UPDATED | READING TIME |
|---|---|---|
| Alkın Ankaralı — Deputy General Manager, Energy Projects | August 2026 | 13 minutes |
Contents
- Summary in five sentences
- What is independent inspection?
- Why is it necessary?
- What does the service cover?
- When should the service be engaged?
- How is independence preserved?
- Who is it meaningful for?
- Frequently asked questions
- Where do you start?
One of the important questions in a solar investment is this: who verifies the work of the firm building the plant, on the investor’s behalf?
On some projects no technical control mechanism independent of the contractor is established for the investor; technical verification is largely left to the EPC contractor’s own quality processes.
Independent inspection — known internationally as the Owner’s Engineer — is a technical verification and reporting function appointed by the investor. The EPC contractor’s own QA/QC process does not replace independent technical verification carried out on the investor’s behalf.
Summary in five sentences
- The objectives of the EPC contractor and the investor can diverge because of the contractual structure; this is not a question of intent.
- Independent inspection verifies that what is built on site conforms to the contract, the specification, the approved project and objective engineering criteria.
- Inspection is not left to the acceptance stage alone; hold point and witness point checks are planned before critical works are closed.
- The fundamental condition of independence is avoiding conflicts of interest that could affect the technical assessment, and not acting as EPC contractor on the same project.
- The service delivers the greatest added value when engaged before the EPC tender and contract process, so that the technical specification, test requirements, document deliverables and acceptance criteria enter the contract from the outset.
The three-party structure — independent verification for the investor
| INVESTOR | EPC CONTRACTOR | INDEPENDENT INSPECTION |
|---|---|---|
| Owner of the plant; its objective is long-term performance and contractual protection | Designs, procures and builds; runs its own QA/QC process | Inspects, verifies, reports and supports the acceptance process technically |
| EPC contract | Responsibility for works and delivery | Inspection contract: technical verification for the investor |
THE LIMIT OF THE ROLE — The inspection body is appointed by the investor and provides independent technical verification on the investor’s behalf. Technical assessments are based on the contract, the specification, the approved project and objective engineering criteria.
What is independent inspection (Owner's Engineer)?
Independent inspection is the review, by an engineering team working on the investor’s behalf and independently of the contractor, of design, equipment, manufacturing, installation, test and commissioning records; the verification of conformity on site; and the reporting of findings.
In this guide, Owner’s Engineer is used in the sense of the investor’s technical adviser. The “Engineer” role in FIDIC contracts, on the other hand, may include contract administration, certification or determination powers defined separately according to the chosen contract form; the two roles are not automatically the same.
- Independent inspection — the service term in common use in Türkiye
- Owner’s engineering — emphasising engineering carried out for the investor
- Owner’s Engineer — the equivalent of the investor’s technical adviser on international projects
In the Owner’s Engineer model addressed in this guide, the inspection service is carried out on the investor’s behalf and the contractual structure is defined accordingly. Within the scope of the project inspected, there must be no conflict of interest arising from the contractor or suppliers that could affect the technical impartiality of the inspection firm.
Why is it necessary? Why do EPC and investor objectives diverge?
An EPC contractor’s task is to deliver the plant within the contract price, scope and schedule. The investor, meanwhile, is concerned with the asset’s long-term performance, reliability and lifecycle cost. The difference is not bad faith; it is a difference of role, information and contractual structure.
The investor is often unable to monitor the following continuously on site:
- Conformity of the DC cabling with the voltage-drop and cross-section calculations in the project
- Torque values and records for the structural connections in the project
- Conformity of the equipment arriving on site with the offer, series and technical class
- Earthing continuity and protection test records
- Conformity of works about to be closed with the approved routes and details
A significant portion of these items becomes difficult to verify directly once the work is complete; some checks can only be made through additional testing, dismantling or costly investigation.
Independent inspection is not distrust of the contractor. Well-run inspection ensures that compliant work is documented with traceable records and that non-conformities are managed early.
What does the service cover?
The scope is defined according to the project, the contract and the risks. The five phases below are a common framework; they need not be identical on every project.
| PHASE | WHAT THE INSPECTION BODY DOES | OUTPUT |
|---|---|---|
| 1 Design | Review of structural/electrical projects, generation assumptions, specification and test criteria | Design review report |
| 2 Manufacturing | Conformity check of equipment and materials against the specification; participation in factory tests where required | Conformity / FAT observation report |
| 3 Site | Verification of installation quality through site checks planned against the works stages | Site inspection reports |
| 4 Testing | Participation in test and commissioning processes; verification of records and results | Test observation / verification records |
| 5 Acceptance | Technical participation in acceptance, follow-up of the punch list and technical opinion | Acceptance technical assessment / closeout file |
Inspection points — control spread across the process
A hold point is the point at which it is agreed in the contract that the work concerned will not proceed to the next stage before notification to the inspection body/employer and completion of the required check. A witness point is a control point at which the inspection body is given the opportunity to observe, and which may proceed under the notification and record conditions in the contract even if attendance does not occur. The application must always be defined in the contract.
WHY CHECK EARLY? — A significant portion of these items becomes difficult to verify directly once the work is complete. Cabling under a closed roof, buried earthing or torque operations that were not recorded may later require additional testing, opening up or dismantling.
A review carried out early at the design stage can prevent significant revisions that would cost time and money on site.
When should the service be engaged?
For the greatest added value, the preferred time is before the EPC tender and contract process.
If the technical specification, test requirements, document deliverables and acceptance criteria enter the contract in advance, the inspection body is more effective. The second-best time is before manufacturing and installation begin.
How is independence preserved?
The fundamental condition of independence is not being in a relationship with the contractor, suppliers or other commercial parties that would create a conflict of interest capable of affecting the technical assessment of the work inspected. That the inspection firm does not act as EPC contractor on the same project is one of the essential elements of this independence.
Technical assessments must be made within the framework of the contract provisions, the technical specification, the approved project and objective engineering criteria; findings must be reported in a traceable manner.
On projects where 11:11 Solar Enerji and its affiliated companies act as EPC Contractor, site inspection services and independent inspection of the implementation projects and engineering calculations issued by the Contractor are not provided. On those projects, engineering services such as preparing the technical specification, feasibility studies, concept design and verification of designs prepared by a third party are provided.
Who is it meaningful for?
Businesses without in-house energy engineering. The investor may need additional capacity to assess the technical file and site progress independently of the contractor.
Corporates investing across more than one site. A common inspection plan and reporting structure supports a consistent quality standard across different sites.
Funds and financial investors. Independent reporting of technical risks provides traceability for investment decisions and asset management.
Investments using project finance. Lending institutions may additionally appoint their own technical adviser or independent engineer.
OWNER’S ENGINEER ≠ LENDER’S ENGINEER — On investments using project finance, lending institutions may additionally appoint their own technical adviser or independent engineer (Lender’s Technical Advisor / Lender’s Engineer). That role differs from the investor’s Owner’s Engineer service. Nevertheless, regular technical reporting, test records, quality documentation and traceable project records can ease lender due diligence and monitoring processes.
Frequently asked questions
Why is independent inspection necessary?
EPC QA/QC is the contractor’s own quality system. Independent inspection, on the other hand, provides third-party verification on the investor’s behalf against the contract and objective technical criteria.
My EPC firm is reliable — is inspection still needed?
Inspection is not an instrument of distrust but the verification of technical conformity through traceable records; the scope is determined by the investor’s risk profile.
I have engineers in-house — is it still necessary?
An in-house engineering team may hold strong technical expertise and plays a critical role in project ownership. The additional value of independent inspection is that it provides project-specific third-party technical verification, specialist site/test experience and independent reporting on the investor’s behalf.
Does inspection slow the project down?
Properly planned, it should not. Writing the inspection and the hold/witness points into the project schedule from the outset allows checks to run in coordination with manufacturing and site activities. Non-conformities detected early reduce the risk of larger rework and delay.
Does the inspection firm carry out the acceptance?
No. Official acceptance is carried out by the competent institution and acceptance committee under the legislation in force. Depending on the contract scope, the inspection body provides technical preparation, review of test records, the punch list and technical opinion/reporting support.
How is the fee for the service determined?
It is determined project by project according to scope, project size, inspection frequency, tests and factory visits, the reporting arrangement and the contractual level of authority.
Where do you start?
The following documents are sufficient at the outset to define an inspection scope:
- The EPC contract or its draft and technical annexes
- Structural/electrical projects, equipment lists and the generation simulation
- Project schedule, quality plan, ITP, hold/witness points
- Site location, capacity information and the envisaged inspection scope
If the contract has not yet been signed, an early review of the technical specification and the test/acceptance criteria can create significant value.
Sources
- FIDIC — About Publications / Contracts and Agreements: the consulting engineer’s role as employer’s representative and the contract structure.
- FIDIC — The Role of the Engineer and related official contract sources: the Engineer’s powers and duties being determined by the chosen contract form.
- World Bank Group, PPP Resource Center — Construction Contracts Checklist: technical adviser review, milestone and payment controls.
- Republic of Türkiye Ministry of Energy and Natural Resources / EİGM — Acceptance and Authorisations pages; official acceptance procedures and competent institutions.
- Regulation on the Acceptance of Electricity Generation and Electricity Storage Facilities — current text.
- Electrical Installations Project Regulation and Electrical Installations Project Approval and Acceptance Authorisations (2025 revision).
- Regulation on Unlicensed Electricity Generation in the Electricity Market — current/consolidated text.
INFORMATION NOTE — This guide is for general technical and contractual information purposes. The inspection firm’s powers, deliverables and role in acceptance processes vary according to the project contract. Official acceptance and statutory OHS responsibilities belong to the parties authorised by the legislation in force.