Choosing the right solar module is about more than a datasheet; it’s a 25-year financial commitment where even a tiny, unforeseen performance decline can have massive consequences.
Underperforming PV equipment already costs operators an estimated $5,720 per MW in lost revenue annually, contributing to a staggering $5.7 billion in global losses.
The crucial question isn’t whether a module passes a baseline test today, but how it will perform in the real world a decade from now. A proactive approach to long-term degradation is therefore essential. While standard tests confirm a module works, our advanced analysis ensures it’s built to endure.
This guide moves beyond simple failure observation. We’ll explore the three primary degradation mechanisms—PID, LID, and LeTID—and detail the testing protocols that transform uncertainty into bankable, long-term asset performance.
The Degradation Gauntlet: PID, LID, and LeTID Explained
While all three can compromise energy yield, they are triggered by different stress factors and require distinct mitigation strategies. Understanding the difference is the first step toward building a truly resilient solar asset.
PID (Potential-Induced Degradation)
Primary Cause: High Voltage Stress
Affected Cell Tech: All, especially older p-type
Key Stress Condition: Voltage, Humidity, Temperature
LID (Light-Induced Degradation)
Primary Cause: Initial Light Exposure
Affected Cell Tech: p-type (B-doped)
Key Stress Condition: Light Soaking
LeTID (Light & Elevated Temperature Induced Degradation)
Primary Cause: Carrier Injection at High Temperature
Affected Cell Tech: PERC, TOPCon, HJT
Key Stress Condition: Light & High Temperature
Standard certification is a starting point, but it often fails to replicate the cumulative stress a module faces over its lifetime. To protect your investment, you need to go further.
Beyond the Standard: The PVTestLab Proactive Protocol
Standard IEC tests confirm that a module meets minimum safety and design thresholds, but they don’t reveal whether it will survive twenty years in a harsh climate. That gap between passing and surviving is where financial risk accumulates.
At PVTestLab, we focus on applied reliability. We use a full-scale, climate-controlled production line to simulate real-world conditions through extended, beyond-standard test sequences. This approach uncovers failure modes that baseline tests miss and provides the data needed for robust financial modeling and proactive material selection.
Decoding & Defeating Potential-Induced Degradation (PID)
PID occurs when a high voltage potential between the cells and the grounded module frame creates leakage currents, leading to a rapid and severe drop in power output. It’s particularly aggressive in hot, humid environments.
PVTestLab Test Protocol: Our protocol goes beyond the IEC 62804 standard, stressing modules for 192 hours at 85°C and 85% relative humidity with full system voltage—double the duration of the standard test. This extended duration mimics years of harsh operational stress, revealing vulnerabilities in module materials and construction.
![Side-by-side electroluminescence (EL) images, one showing a healthy module and one showing the dark, inactive cells characteristic of severe PID.]
Measurable Results & Mitigation: Our testing precisely quantifies power loss. We’ve seen modules lose over 30% of their power from PID effects that only became apparent after the standard 96-hour mark. This data allows developers to validate mitigation strategies, such as selecting modules with PID-resistant encapsulants (like Polyolefin Elastomer, POE) or using anti-PID cell technology. The result is a validated design that delivers stable performance.
Unmasking & Mitigating Light-Induced Degradation (LID)
LID is an initial power drop that occurs within the first hours of a module’s exposure to sunlight, primarily affecting p-type cells with boron doping. While often accounted for in performance models, incomplete characterization can lead to inaccurate estimates of a project’s initial yield.
PVTestLab Test Protocol: We perform advanced LID characterization to precisely measure a module’s stabilization curve. By controlling light intensity and temperature, we can isolate LID from other effects and provide an accurate degradation factor, enabling a deeper analysis of how different cell technologies and materials behave.
Validated Improvement Actions: Our analysis helps manufacturers validate LID-resistant technologies. For example, our tests can confirm the superior stability of Gallium-doped silicon wafers over traditional Boron-doped ones. For asset owners, this means having confidence that the 0.5% degradation rate in their financial model is accurate, not a hopeful guess. When you need certainty about material performance, our material testing and lamination trials (https://www.pvtestlab.com/services/material-testing) provide the definitive data.
Mastering the LeTID Challenge: The Unaddressed Threat
Light and Elevated Temperature Induced Degradation (LeTID) is a more recent and insidious threat, primarily affecting high-efficiency cells like PERC and TOPCon. It can cause significant power loss—sometimes over 10%—that appears after hundreds of hours of operation and can even recover and reappear later. Standard LID tests miss it completely.
PVTestLab Test Protocol: For LeTID, beyond-standard testing is non-negotiable. Our protocol is designed to reveal this complex mechanism by subjecting modules to extended thermal cycling at 75°C with current injection for over 486 hours. This sequence is specifically engineered to trigger the degradation and regeneration cycles characteristic of LeTID, providing a true picture of a module’s long-term stability in hot climates.
![A line graph comparing the power degradation of two modules under LeTID testing. One module with a standard encapsulant shows a steep drop, while a module with a validated POE encapsulant remains stable.]
Validated Improvement Actions: Our LeTID testing provides the crucial data needed to make informed decisions about module components. We can definitively validate how well different encapsulants or cell passivation techniques suppress LeTID. This empowers developers to specify modules with proven resistance, de-risking projects in high-temperature regions and ensuring today’s high-efficiency gains don’t become tomorrow’s performance liability.
From Data to Decisions: Your Bankability Blueprint
Ultimately, degradation testing isn’t an academic exercise—it’s a financial necessity. The insights gained from advanced reliability testing form the foundation of a bankable solar project.
For Module Developers: Our data provides a clear roadmap for material selection and process optimization, enabling you to build more robust products with a competitive edge.
For Asset Owners & Financiers: Our reports deliver precise, accurate degradation data that reduces uncertainty in energy yield models, satisfying the stringent due diligence requirements of financial institutions.
By partnering with PVTestLab, you move from observing failures to proactively engineering resilience.
Frequently Asked Questions
Isn’t standard IEC certification enough to guarantee quality?
IEC certification is an essential baseline for safety and fundamental design, but it is not a predictor of long-term performance or reliability. The tests are often too short and not stressful enough to reveal degradation mechanisms like LeTID that manifest over thousands of hours in real-world conditions. Our beyond-standard protocols are designed to fill this critical gap.
How is your testing different from other labs?
Our key differentiator is our applied research environment. Unlike purely academic labs or high-volume certification houses, we conduct our tests on a full-scale industrial production line with integrated support from German process engineers. This unique setup allows us to not only identify a failure but also help you understand its root cause in the manufacturing process and test potential solutions in a real-world setting. We bridge the gap between laboratory data and factory-floor reality.
Can you test specific new materials we are considering, like a new encapsulant?
Absolutely. Material validation is a core part of our service. Our prototyping and module development (https://www.pvtestlab.com/services/prototyping) capabilities allow you to build test modules with your specified materials and then subject them to our rigorous degradation protocols. The result is empirical, comparative data showing how different materials perform under identical, controlled stress conditions.
How does this level of testing impact my project’s financial model?
It replaces assumptions with certainty. Instead of using generic degradation rates (e.g., 0.5% per year), our testing provides a specific, data-backed degradation profile for your chosen module. This reduces uncertainty in your energy yield predictions, making your financial model more robust and attractive to investors. This helps you avoid the $5,720 per MW annual loss that comes from unexpected underperformance.
De-Risk Your Next Project with Applied Reliability Testing
Don’t let hidden degradation mechanisms compromise your long-term returns. Gain the confidence that your technology will perform as promised, year after year.
Schedule a technical consultation with one of our process specialists to discuss your project’s specific reliability and bankability requirements.