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GBP K.K. outlines when solar modules need replacement or further assessment

GBP K.K.

Key Facts:

• GBP K.K. has outlined a framework to help solar asset owners and maintenance teams assess suspect photovoltaic modules, categorising required actions into four types: isolate, replace, investigate, or monitor, based on safety risk, performance impact, and whether a defect is deteriorating.
• Continued electricity generation does not confirm a module is safe, as defects such as broken glass or cell cracks can compromise mechanical protection or electrical insulation whilst output is maintained.
• Visual appearance alone is insufficient for decision-making, as discolouration, cell cracks, and thermal anomalies each carry different implications, and there is no universal colour or temperature threshold that determines when replacement is necessary.
• A combination of diagnostic methods is recommended, including visual inspection, infrared thermography, current-voltage testing, electroluminescence imaging, and insulation testing, as no single method identifies all defects or safety risks.
• When replacement is required, matching nominal wattage alone is insufficient; electrical characteristics, dimensions, connector type, mounting requirements, and mechanical loading must all be reviewed against the existing string, inverter, and installation.

A practical framework helps solar asset owners and maintenance teams distinguish immediate safety risks from defects requiring investigation or monitoring.

GBP K.K. outlines a framework for assessing suspect photovoltaic (PV) modules, helping solar asset owners and maintenance teams decide when to isolate, replace, investigate or monitor affected equipment.

The framework considers three factors: whether a module presents a safety risk, how the defect affects performance, and whether its condition is deteriorating. It explains why continued electricity generation does not establish that a module is safe, and why visible defects require assessment before a replacement decision is made.

Broken glass illustrates the distinction. A module may continue producing power even when its mechanical protection or electrical insulation is compromised. A crack within a silicon cell requires a different assessment: it may have little immediate effect, but can contribute to power loss or hot spots if it isolates active cell area or propagates.

The framework sets out four possible actions:

• Isolate: Where a credible immediate electrical, fire, mechanical or personnel-safety risk exists, qualified personnel should follow site isolation and access-control procedures and assess the affected equipment.

• Replace: Where a confirmed defect breaches safety or operating requirements, or replacement is the approved decision over the remaining service life, preserve evidence and confirm replacement compatibility.

• Investigate: Where the cause, extent or consequence is uncertain, select tests that resolve the remaining questions and compare results against a valid reference.

• Monitor: Where a defect is understood, stable and accepted below a documented project-specific risk threshold, assign responsibility, set review dates and define escalation triggers.

Assess the consequence, not appearance alone

Discolouration, cell cracks and thermal anomalies do not provide the same information. Discolouration may be cosmetic or indicate degradation. Unusual heating may result from shading, reflections, bypass-diode operation, mismatch, poor connections or a hot cell.

There is no universal colour or temperature-difference threshold for replacement. Findings should be assessed against measurement conditions, module design, manufacturer requirements and site risk controls.

Low output also requires checks beyond the module. Soiling, shading, sensor errors, weather conditions, inverter clipping, wiring and fuses can affect measured performance.

 

Use targeted inspection and testing

No single diagnostic method identifies every defect or establishes every safety risk.

Visual inspection can identify broken glass, frame or backsheet damage, junction-box problems, discolouration and delamination. Infrared thermography can locate unusual heating, although irradiance, wind, viewing angle and operating conditions influence the result.

Current-voltage testing assesses electrical performance and curve shape, with appropriate temperature and irradiance corrections. Electroluminescence can reveal cell cracks and inactive areas. Insulation and safety testing helps assess electrical safety and suitability for return to service.

After hail, intact-looking glass does not rule out cell microcracks. Where storm damage is visible, the affected system should remain shut down pending qualified visual and electrical inspection, with electrical faults checked before repowering.

Record decisions and check replacement compatibility

Assessment records should identify the module, observations, test conditions, comparison baseline, excluded causes and reasons for the decision. Monitoring plans should specify who is responsible, when inspections will occur and which changes require escalation.

Where replacement is necessary, matching nominal wattage alone is insufficient. Electrical characteristics, dimensions, connector type, mounting requirements and mechanical loading must be reviewed against the existing string, inverter and installation.

GBP K.K. can support this review using existing module datasheets, string and inverter configurations, site conditions, dimensional constraints and defect records. Proposed replacements remain subject to project approval and recommissioning under applicable safety and technical procedures.

About us:

Based in Japan, GBP K.K. offers end-to-end renewable energy solutions — from solar component manufacturing and system design to construction and O&M. Feel free to reach out to us for anything renewable energy related!