What Industrial Solar PV Commissioning in MENA Gets Wrong — And Why Most Plants Start Underperforming Before the First Invoice

The handover certificate is signed. The EPC contractor shakes hands with the project owner. The monitoring system shows green across every inverter. While everything looks perfect on paper, the traditional industrial solar PV commissioning process often harbors a silent threat. The Performance Ratio calculation, run quickly against the irradiance data from the previous day, falls within the contractual acceptance range.

The plant is officially commissioned.

And on that same day — before a single invoice has been issued, before the first month of production has been recorded, before anyone has had time to notice — a meaningful fraction of its 25-year financial return has already been compromised.

Not by equipment failure. Not by design error. By the gap between what commissioning testing is required to find and what it is actually capable of finding — a gap that aerial thermographic survey data across a cumulative fleet of nearly 400 GW of installed solar capacity shows is present at commissioning in the overwhelming majority of installations worldwide.

The average power loss at commissioning, measured across this global dataset, is 4.46%. The 2025 fleet-wide average for operating plants is 5.08%. In other words, installations are being handed over carrying almost the same anomaly burden as plants that have been operating for years.

On a typical C&I industrial installation generating approximately 180,000 USD per year per MWp in energy savings, a 4.46% performance loss baked in at commissioning represents approximately 8,028 USD per year per MWp in avoidable production shortfall — compounding to over 200,000 USD per MWp across a 25-year project lifetime. From defects that were present before the first invoice was issued and that a rigorous commissioning program would have identified and corrected.

The commissioning process — designed to verify that everything works — is certifying as acceptable a performance level that already includes most of the underperformance those plants will carry for their entire operational life.

This is the conversation that almost never happens at handover. This article is that conversation.

Disclosure: This article contains affiliate links. If you purchase through these links, I may earn a small commission at no extra cost to you. I only recommend technical resources that I consider genuinely useful for industrial solar professionals working in Africa and the MENA region.

What Commissioning Is Supposed to Do — And the Gap Between Intent and Reality

The intent of solar PV commissioning is clear and well-defined. Testing follows a logical sequence from DC circuits through AC systems to grid interconnection. Open-circuit voltage testing verifies that each string produces expected voltage under actual conditions. Insulation resistance testing confirms that the wiring is safe. Performance ratio measurement, conducted under adequate irradiance conditions, confirms that the system achieves its contractual output.

These tests serve a real and important purpose. They catch wiring errors, polarity reversals, fuse failures, and communication faults. They confirm that the basic electrical architecture of the installation is correct and safe. They provide the documentation that triggers warranty periods and commercial operation dates.

What they do not do — and what the industry literature increasingly acknowledges — is find the most financially consequential defects that are present at commissioning.

The tests that would find these defects are classified as optional in IEC 62446 — the primary international standard governing solar PV commissioning documentation and testing. Optional means they are performed when the project specification requires them. In practice, for the overwhelming majority of C&I industrial installations in MENA and Africa, they are not required and not performed.

The consequence is measurable: plants commissioned with the standard mandatory test suite are handed over carrying defects that will silently erode performance for years — defects that a one-day extended commissioning program would have identified and resolved before commercial operation began.

The Five Tests That Should Be Standard on Every MENA Industrial Installation

Test 1 — Electroluminescence imaging of the full array

An electroluminescence test passes a small current through each solar panel and images the resulting light emission with a calibrated camera. Cells with micro-cracks, disconnected interconnects, manufacturing defects, or installation damage emit less light than healthy cells — producing a characteristic pattern that is visible in the EL image and invisible to any other test or inspection method.

Cross-mated DC connectors — a leading cause of solar PV fires — pass every mandatory test in the commissioning standard. The insulation resistance between a mismatched pair reads within acceptable limits under dry conditions. The IV curve of the affected string may show a small deviation that falls within the measurement uncertainty of a field instrument. Only EL imaging, or a thermal imaging test under load, reliably identifies cross-mated connectors before they develop into a more serious fault.

In high-irradiance, high-thermal-cycling environments comparable to MENA industrial sites, micro-crack propagation from installation handling and transport is accelerated by the aggressive daily thermal cycling that begins from the first days of operation. A panel that shows a contained micro-crack in an EL image at commissioning — classified as non-critical under standard acceptance criteria — may progress to a bypass diode activation pattern within two to three seasons of MENA thermal cycling that would be classified as critical if found later. The commissioning EL image is not just a defect inventory. It is a risk map for what the MENA climate will amplify over the project lifetime.

A peer-reviewed study published in January 2026 found that 13.5% of field-aged modules were classified as dry-pass — they passed insulation resistance testing under dry conditions but showed defects under humid conditions. In MENA environments where diurnal temperature variation creates condensation cycles on panel surfaces overnight, the dry-pass failure mode is not a theoretical concern. It is a predictable operational reality.

EL imaging cost: approximately 0.05% to 0.15% of total installation cost. Consequence of not performing it: defects present at commissioning propagate silently for months or years before producing a detectable production signature.

Test 2 — Thermal imaging under operating load

A thermal imaging inspection conducted under load — with the array producing at or near rated output under stable irradiance — identifies hot spots, active bypass diode faults, and connection resistance anomalies that are invisible under open-circuit or low-irradiance conditions.

Field experience on industrial installations confirms that soiling-induced hot spots — where localized soiling creates thermal stress concentrations that accelerate cell degradation — are present from the first weeks of operation on heavy industrial sites. A thermal imaging baseline established at commissioning provides the reference against which all subsequent inspections are compared.

Without a commissioning thermal baseline, there is no contractual basis for attributing a hot spot found in year two to an installation defect rather than to operational conditions. The distinction matters for warranty claims and for insurance purposes — and it is a distinction that cannot be established retroactively.

Thermal imaging cost at commissioning: included in the O&M scope at negligible incremental cost when conducted during the commissioning period — before the operational team has demobilized and while the EPC contractor is still on site to address findings.

Test 3 — IV curve tracing on a statistical sample

The current-voltage characteristic curve of a solar panel is its most complete electrical fingerprint. An IV curve tracer measures the full relationship between current and output voltage across the operating range — producing a curve whose shape, peak power point, and fill factor reveal the electrical condition of the panel in a way that no single-point measurement can replicate.

IV curve tracing on a statistically representative sample — typically 5% to 10% of panels on a C&I installation — establishes the true production baseline at commissioning. It quantifies the Light-Induced Degradation that has already occurred in the first weeks of operation. And it provides the measurement that makes warranty claims defensible: if the panels are already producing measurably below their flash-test specification at commissioning, that deviation is a manufacturer’s responsibility, not an operational one.

In MENA conditions, where LID stabilizes faster due to higher irradiance intensity, the IV curve test should be conducted after a minimum two-week light soak period — not on the day of installation, when LID has not yet fully manifested.

Test 4 — Protection relay parameter verification and simulation

Field analysis documented across multiple industrial solar installations in MENA shows that protection relay parameters — including the residual voltage threshold and timing that determines how quickly the plant trips on an earth fault — are frequently set to default values that are not optimized for the specific installation’s electrical characteristics.

A protection relay parameter verification at commissioning — including a simulated earth fault test that confirms the relay responds correctly to the specific fault conditions of this installation — is not a standard commissioning requirement. It should be, on any installation where the protection scheme includes a residual voltage function connected to medium-voltage infrastructure.

The cost of a nuisance trip caused by an incorrectly parameterized relay — in lost production, inverter restart time, and potential equipment stress — compounds every time the fault condition is present. The cost of verifying the parameters correctly at commissioning is a few hours of an experienced protection engineer’s time.

Test 5 — Performance Ratio baseline with full temperature and irradiance correction

The standard commissioning PR test produces a single performance ratio value that serves as the contractual acceptance criterion. What this test does not produce is a baseline that is comparable across different irradiance and temperature conditions — unless both are corrected to a common reference condition using the panel’s temperature coefficient and the irradiance correction factor.

A properly corrected PR baseline — documented at commissioning with full measurement conditions recorded — is the reference against which every subsequent monthly PR calculation should be compared. Without it, performance drift is measured against a moving target.

With it, a 2% decline in corrected PR over 18 months is a precise, defensible, quantifiable finding — not an impression that something might be underperforming.

“For engineers and project managers responsible for specifying or supervising the commissioning of industrial solar installations in MENA — and who want to build a rigorous technical foundation covering commissioning standards, acceptance testing methodologies, and handover documentation requirements — Solar PV Engineering and Installation by Sean White provides one of the most practically oriented treatments available of the commissioning process from design through to operational handover. It is particularly useful for anyone negotiating EPC contract commissioning clauses or reviewing a handover pack for completeness.

The Industrial Solar PV Commissioning Process: A Complete Sequence

The following diagram shows the complete commissioning sequence for an industrial solar installation — including where the mandatory tests occur and where the most financially consequential optional tests should be inserted:

flowchart TD
    A[Construction Complete] --> B[DC Circuit Testing\nVoc and Isc per string]
    B --> C[Insulation Resistance Testing\nAll strings and subarrays]
    C --> D[AC System Testing\nInverter configuration\nGrid connection]
    D --> E{PR within\ncontractual\nacceptance range?}
    E -->|Yes| F[PAC Issued\nCommercial Operation]
    E -->|No| G[Investigation\nand Correction]
    G --> D
    F --> H[EL Imaging\nFull array\n⚠ Optional — should be mandatory]
    F --> I[Thermal Imaging\nUnder operating load\n⚠ Optional — should be mandatory]
    F --> J[IV Curve Tracing\nStatistical sample\n⚠ Optional — should be mandatory]
    F --> K[Protection Relay\nParameter verification\n⚠ Optional — should be mandatory]
    H --> L{Defects\nidentified?}
    I --> L
    J --> L
    K --> L
    L -->|Yes — present in majority\nof installations| M[Correction Before\nFull Operation]
    L -->|No| N[Baseline Documentation\nComplete]
    M --> N
    N --> O[Operational Baseline\nEstablished — Day 1]
    style H fill:#ff6b6b,color:#fff
    style I fill:#ff6b6b,color:#fff
    style J fill:#ff6b6b,color:#fff
    style K fill:#ff6b6b,color:#fff
    style L fill:#ffd93d,color:#000
    style O fill:#51cf66,color:#fff

Legend: 🔴 Red = optional tests that should be systematic on every MENA industrial installation | 🟡 Yellow = critical decision point | 🟢 Green = operational baseline established

The Financial Case for Extended Commissioning Testing

The argument against extended commissioning testing is always the same: cost and time. The EPC contractor has a handover deadline. The project owner wants commercial operation to begin. Adding tests that are not contractually required delays handover and adds cost.

The five extended commissioning tests documented in this article have a combined cost of approximately 15,000 to 40,000 USD on a typical multi-megawatt C&I installation. Against a commissioning performance deficit of 4.46% that compounds across a 25-year project lifetime into over 200,000 USD per MWp in avoidable losses — the return on this investment is not a financial argument. It is arithmetic.

A defect detected at commissioning costs the price of correction — typically a panel replacement, a connector re-termination, or a relay parameter adjustment. The same defect detected six months after commercial operation costs the correction plus six months of production loss. The same defect undetected for three years costs three years of production loss plus a correction whose cause may no longer be attributable under the original EPC warranty.

The EL imaging test that finds a cross-mated connector at commissioning costs approximately 2,000 to 5,000 USD on a typical C&I industrial installation. The production loss from a cross-mated connector that develops into a resistance fault over two years of operation affects one or more strings for the full duration — with the fire risk in a MENA summer adding a safety dimension that no financial calculation fully captures.

What the Handover Documentation Should Include — And Usually Does Not

The handover pack is the document set transferred from the EPC contractor to the project owner at commercial operation. Field experience across industrial solar installations confirms that handover packs are frequently incomplete — missing documents that are critical for effective maintenance over the project lifetime and that cannot be reconstructed after the EPC team has demobilized.

Any item in this table that is missing from the handover pack at commercial operation represents information that will be needed at some point during the 25-year operational life of the installation — and that will be significantly harder and more expensive to reconstruct after the EPC contractor has demobilized.

What to Specify in the EPC Contract — Before Commissioning Begins

The most effective intervention in the commissioning process happens before construction starts — in the EPC contract. These clauses must be included before the tender process closes — not negotiated after contractor selection, when the leverage to add scope is significantly reduced. The appropriate representative to negotiate these clauses is the independent engineer or technical advisor, if one has been appointed, or the technical director of the project owner directly.

Clause 1 — EL imaging as a commissioning acceptance criterion

“Full-array electroluminescence imaging shall be conducted following a minimum light soak period of fourteen days after mechanical completion. The EL imaging results shall be provided to the owner as part of the handover documentation. Any module showing defects classified as critical per IEC 60904 shall be replaced prior to final acceptance.”

Clause 2 — Thermal imaging under load as a commissioning acceptance criterion

“Thermal imaging of the full array shall be conducted under stable irradiance conditions of not less than 600 W/m² at an incidence angle of less than 45°. Results shall be documented with GPS-referenced panel locations and provided to the owner as part of the handover documentation.”

Clause 3 — IV curve tracing baseline

“IV curve tracing shall be conducted on a minimum of 5% of installed panels, selected as a statistically representative sample. Results shall be compared against flash test data and documented as the commissioning performance baseline.”

Clause 4 — Protection relay parameter verification

“Protection relay settings shall be verified against the protection coordination study at commissioning. A simulated earth fault test shall confirm correct relay response under the specific electrical conditions of the installation. The verified settings sheet shall be included in the handover documentation.”

Clause 5 — Corrected PR baseline documentation

“The commissioning Performance Ratio measurement shall be corrected to Standard Test Conditions using the panel temperature coefficient and measured irradiance values. The corrected PR, with all measurement conditions documented, shall form the contractual performance baseline for the operational period.”

Each clause has an associated cost implication for the contractor that should be reflected in the tender price — not absorbed as an afterthought during mobilization.

The handover certificate marks the beginning of 25 years of operational responsibility — not the end of the EPC contractor’s accountability. The defects that are present at commissioning but undetected by the mandatory test suite do not disappear when the certificate is signed. They begin their compounding work on day one of commercial operation — silently, in the production data that looks acceptable until it is compared against a baseline that was never properly established.

Aerial thermographic data across nearly 400 GW of installed solar capacity shows that the average power loss at commissioning is 4.46% — before soiling, before thermal derating, before any operational degradation has had time to develop. That loss is baked in before the first invoice.

The five extended commissioning tests documented in this article — EL imaging, thermal imaging under load, IV curve tracing, protection relay verification, and corrected PR baseline documentation — would find and allow the correction of most of this baked-in performance loss before commercial operation begins. Their combined cost of 15,000 to 40,000 USD is a fraction of one percent of any meaningful C&I installation value. Their combined benefit is a 25-year project that starts from a true, verified, contractually defensible baseline rather than an optimistic assumption certified by a process that was never designed to find the most expensive defects.

The commissioning week is the last opportunity to correct what the construction phase introduced. It is also the moment when the operational team’s leverage over the EPC contractor is at its maximum — and when the cost of finding and fixing defects is at its lowest.

That combination of maximum leverage and minimum correction cost will not return. The handover certificate closes it permanently.

The Performance Ratio baseline methodology, protection relay field observations, and commissioning gap analysis referenced in this article reflect field experience on industrial solar installations in MENA. The operational dataset — including two years of monthly PR measurements from commissioning baseline through sustained operation — is documented in the MENA Industrial Solar Data Guide.

For anyone specifying or reviewing an industrial solar commissioning program in MENA, the guide provides the measured performance trajectory that makes the commissioning baseline argument concrete: the difference between a plant that starts from a verified baseline and one that starts from an assumption is visible in the data from month one.

Get the Free Preview

The first 8 pages of the MENA Industrial Solar Data Guide — real Performance Ratio data, soiling measurements, and thermal derating figures from an industrial installation— No spam, just real data.

Email Name

Name *

Email *

Submit

Disclosure: This article contains affiliate links. If you purchase through these links, I may earn a small commission at no extra cost to you. I only recommend technical resources that I consider genuinely useful for industrial solar professionals working in Africa and the MENA region.

Publié par :

Solar PV MENA Expert