Quality Control on Renewable EPC Projects: ITPs, Hold Points and Punch Lists

The project quality plan

Every renewable EPC project should start with a quality plan that sets out how quality will be managed: responsibilities, standards, procedures, document control, inspection and testing, handling of non-conformance and records. It applies to the contractor, its subcontractors and its suppliers.

The owner reviews the plan at the start of the project and checks during construction that it is being followed. A plan that sits on a shelf adds nothing; a plan that drives daily inspections is the foundation of a good plant.

Inspection and test plans

Inspection and test plans, often called ITPs, list each activity, the inspections and tests required, the acceptance criteria, the records produced and who performs or witnesses each step. Separate ITPs typically cover civil works, piling, mounting structures, module installation, electrical works, substations and commissioning.

A good ITP is specific: it names the test, the instrument, the sampling frequency and the acceptance value. Vague entries such as check installation give no basis for acceptance or rejection.

Hold and witness points

Some activities cannot proceed until an inspection is passed. These are hold points, and they often require the owner or its engineer to attend. Witness points allow the owner to attend if it chooses, with notice given in advance.

Typical hold points include pile testing before mass installation, concrete pours for substation foundations, cable insulation tests before energisation and protection tests before connection. Agree notice periods so inspections do not delay the work.

Supplier and factory quality

Major equipment such as modules, inverters, transformers and wind turbine components should be inspected at the factory or before shipment. Factory acceptance tests, sample testing and document review catch defects before they reach site.

For modules, many owners commission independent factory audits and sample testing. For transformers and switchgear, factory acceptance tests are standard and worth witnessing.

Site inspection and sampling

On site, inspectors check work against drawings and specifications as it progresses. Because renewable plants are repetitive, statistical sampling is common: a percentage of piles, torque checks, string connections or cable terminations is inspected, with the sample increased if defects are found.

Early inspections of the first rows or first turbines are especially valuable. Problems found at the start can be corrected before they are repeated across the site.

Handling non-conformance

When work does not meet requirements, a non-conformance report records the problem, its cause and the corrective action. Some non-conformances are fixed by rework, some are accepted with a concession, and some require design changes. Each should be closed formally with evidence.

Trends in non-conformance reports point to systemic issues such as unclear drawings, poor workmanship or faulty materials. Addressing the cause prevents repeat defects.

Commissioning and testing

Commissioning tests prove that systems work as designed: insulation tests, string tests, inverter tests, protection tests, SCADA tests and energisation. They are part of the quality chain and should follow approved procedures with recorded results.

Our article on the renewable EPC commissioning sequence explains how tests are ordered from mechanical completion to commercial operation.

The punch list

As the project nears completion, a punch list records remaining defects and incomplete items. Items are often grouped into categories: those that must be fixed before energisation or taking over, and minor items that can be fixed afterwards within an agreed period.

A clear punch list with owners and dates prevents disputes at handover. Payment milestones are often linked to clearing punch list categories, as covered in our article on renewable EPC payment milestones.

The owner’s role in quality

Owners do not need to inspect every pile, but they should know how quality is being managed. Appoint an owner’s engineer or site representative, attend hold points that matter most, review inspection records regularly and track non-conformance trends. Monthly quality reports from the contractor, with open issues and closure dates, give the owner a clear view without duplicating the contractor’s work.

Lenders and their independent engineers will often ask for the same records. Keeping them organised from the start saves effort at financial close milestones and at completion.

Quality on hybrid and firmed plants

Where a renewable plant includes batteries, engines or gas turbines for firming, the quality plan must cover those systems too. Rotating equipment, fuel systems and control integration bring inspection and test requirements that differ from solar and wind. Make sure the inspection and test plans cover the interfaces, particularly controls, protection and metering, where most hybrid commissioning problems appear.

Handover documentation

At handover, the owner should receive as-built drawings, test records, quality records, manuals, warranties and spare parts lists. These documents support operation, maintenance, warranty claims and future refinancing.

Build the handover package during construction, not at the end. Our article on solar farm construction shows how documentation fits into the construction programme.