Hot spots and delamination are frequently discussed as separate solar failure modes, but in practice they feed each other — a hot spot can accelerate delamination, and delamination frequently creates the resistance conditions that produce a hot spot in the first place.

What a Hot Spot Actually Is

A hot spot forms when one cell or a section of a cell produces significantly less current than its neighbors, often because of shading, a micro-crack, or a manufacturing defect. Because cells in a string are wired in series, the underperforming cell is forced to dissipate the excess current from the rest of the string as heat rather than passing it through, sometimes reaching temperatures well above the surrounding panel surface. Sustained hot spots degrade the encapsulant and can, in severe cases, damage the backsheet or create a fire risk.

What Delamination Is and Why It Matters Here

Delamination is the failure of the adhesive bond between a panel’s laminated layers — glass, EVA encapsulant, silicon cells, and backsheet — creating air voids where a solid bond used to hold the assembly together. It typically originates from moisture ingress through a weak edge seal, thermal-cycling stress on mismatched-expansion materials, UV degradation of the encapsulant, or inconsistent lamination during manufacturing.

How the Two Failures Interact

Delamination raises the resistance of the electrical contacts it exposes to moisture and corrosion. That elevated resistance is itself a hot-spot-generating condition, since current forced through a higher-resistance path dissipates more energy as heat right at that location. The reverse is also true: a hot spot’s sustained elevated temperature accelerates the thermal-cycling and UV-driven degradation mechanisms that cause delamination, weakening the surrounding bond faster than ambient conditions alone would. Once this feedback loop starts, the two failure modes tend to progress together rather than independently, making an isolated diagnosis of either one incomplete without checking for the other.

Detecting the Combined Failure

Infrared thermography is the primary tool for finding hot spots, since the elevated temperature difference from surrounding cells is directly visible on a thermal camera. The same imaging pass often reveals whether the hot spot correlates with a delaminated area, since both produce a similar thermal signature from resistance-driven heat dissipation. Electroluminescence imaging goes further, distinguishing a hot spot caused by a micro-crack from one caused by delamination-driven corrosion, which matters for deciding on a repair versus replacement approach. Visual inspection alongside I-V curve tracing rounds out a complete diagnostic pass, since the current-voltage dip from a hot spot and from general delamination-driven resistance can look similar without more targeted imaging. Email Us if your team needs help interpreting combined thermal and electroluminescence results.

Preventing the Feedback Loop

High-quality manufacturing and component selection make the biggest difference before installation — panels validated through damp-heat and thermal-cycling qualification testing are measurably less likely to develop either failure mode in isolation, let alone in combination. Professional installation matters too: correct mounting technique and avoiding mechanical stress on the modules prevents the micro-cracks that seed early hot spots. Regular operations and maintenance, including scheduled thermal imaging passes, catches the earliest stage of either failure before the feedback loop has a chance to compound.

A Practical Inspection Sequence

For a technician working through an array, a practical sequence is to run a full thermal imaging pass first to flag any cell or panel running hotter than its neighbors, then cross-reference each flagged location against the panel’s visual condition for bubbling, cloudiness, or browning consistent with delamination. Panels with a thermal anomaly but no visible delamination warrant closer inspection for a micro-crack or shading cause instead, while panels showing both a thermal anomaly and visible bond failure should be prioritized for electroluminescence testing and warranty documentation, since these are the cases most likely to be progressing quickly.

The Economic Stakes

A combined hot-spot-and-delamination failure degrades faster than either issue would alone, meaning the panel reaches a replacement-worthy condition sooner than a standard degradation curve would predict. That accelerated timeline directly undermines the return-on-investment assumptions behind a solar project, and the added safety exposure from a persistent hot spot raises liability and insurance considerations well beyond the lost energy value alone.

Materials That Break the Cycle

Because the feedback loop depends on resistance and heat compounding at a weak bond, the encapsulant and edge-sealing materials used at manufacturing time determine how resistant a module is to the whole interaction, not just to delamination in isolation. Incure’s UV-curable adhesive and encapsulation systems are formulated to resist the moisture ingress and thermal-cycling stress that start this cycle, the same durability principle behind why CTE mismatch drives adhesive bond failure and selecting adhesives built for heavy-duty, long-service applications.

Treating hot spots and delamination as connected rather than separate diagnostic questions gives a more accurate picture of a panel’s actual condition — and catches the compounding risk before it accelerates past the point where monitoring alone is still a reasonable response. Contact Our Team to discuss adhesive and encapsulant solutions for improving module reliability.

Visit www.incurelab.com for more information.