Commissioning and handover: a checklist for owners

After months of construction, the plant is nearly finished. Commissioning and handover are the final steps, and they matter enormously. This is the owner's last real chance to make sure the plant is built as specified, works as promised and comes with everything needed to run it for decades. Rushing handover to hit a date often means inheriting problems that are much harder to fix later.

Commissioning vs handover

• Commissioning — testing systems to prove they are installed correctly and perform as designed
• Handover — formal transfer of the plant, documents and responsibility from the EPC contractor to the owner

Between them sits a series of tests, inspections, approvals and documentation checks.

Stages of commissioning

1. Pre-commissioning

Checks before energisation:

• Visual inspections of installation
• Mechanical completion checks
• Cable insulation and continuity tests
• Earthing and lightning protection tests
• Protection relay settings checked
• Transformer and switchgear tests

2. Energisation

• Statutory electrical inspection approvals obtained before energisation, as required. See renewable project approvals overview.
• Step-by-step energisation of substation, transformers and feeders

3. Functional testing

• Inverters and turbines started and tested
• SCADA and monitoring systems checked
• Protection systems tested
• Communication with system operators established

4. Grid synchronisation

• Synchronisation with the grid under utility supervision
• Grid compliance tests as required

5. Performance testing

• Solar: capacity test and performance ratio test over a defined period. See solar performance ratio and availability.
• Wind: turbine reliability run and, where specified, power curve verification

Test procedures, durations and acceptance criteria should be defined in the EPC contract.

The commissioning checklist

Tests

• All pre-commissioning tests completed and recorded
• Owner's representative witnessed key tests
• Protection settings verified
• Performance tests completed per contract
• Results reviewed and accepted in writing

Approvals

• Electrical inspectorate approvals received
• Utility approvals for synchronisation and COD
• Any other required approvals obtained

Punch list

• Punch list compiled jointly
• Items categorised by severity
• Deadlines agreed for each item
• Safety-critical items closed before handover

Documentation

• As-built drawings — layout, electrical, civil
• Equipment datasheets and manuals
• Test reports and certificates
• Warranty certificates, with serial numbers
• Operation and maintenance manuals
• Spare parts list and initial spares delivered
• SCADA configuration and access credentials
• Approvals and their conditions

See project documentation file.

Training

• O&M team trained on equipment and systems
• Safety procedures handed over
• Emergency response plans in place

Commercial

• Handover certificate signed
• Defect liability period start date recorded
• Retention and security arrangements clear
• Insurance transferred from construction to operation

Witnessing tests

Owners or their representatives should witness key tests, not just receive reports. Witnessing:

• Confirms tests are done properly
• Catches problems early
• Builds the owner team's knowledge of the plant
• Provides independent evidence for warranty claims later

Managing the punch list

A punch list records incomplete or defective items. Good practice:

• Walk the site jointly with the contractor
• Photograph each item
• Classify by safety, performance and cosmetic
• Agree deadlines and track closure
• Retain payment until items are closed, where the contract allows

Defect liability period

After handover, the EPC contractor is typically responsible for fixing defects for a defined period. During this time:

• Record every defect with date, description and photographs
• Notify the contractor formally, as the contract requires
• Track response and resolution
• Inspect before the period ends, so remaining defects are claimed in time

See solar O&M: what owners should expect.

Transition to O&M

Handover marks the start of operations. The O&M team — in-house or contracted — should be involved before handover, attending tests and reviewing documentation. A smooth transition avoids early losses. See structuring O&M contract KPIs.

When performance tests fall short

If a capacity or performance test misses the contractual threshold, the contract usually sets out what happens next: investigation, remedial work, a retest within a defined period, and if the shortfall persists, liquidated damages or other remedies. Before accepting any explanation, check that test conditions — irradiance, temperature, sensor calibration, grid availability — met the procedure. Agree in writing how the shortfall will be resolved before signing the handover certificate.

Common mistakes

• Accepting handover to meet a date with major items open
• Not witnessing performance tests
• Incomplete as-built documentation
• Losing track of warranty serial numbers
• O&M team not involved until after handover

How we help

Through project management and execution support, we coordinate commissioning on the owner's side — witnessing tests, managing punch lists, collecting documentation and setting up the transition to O&M.