Thermal vs. Mechanical Anomalies: Everything You Need to Know
Whoever operates and is interested in the Renewable Energy Industry knows that the lifespan of a PV panel is pretty long. We’re talking about 20-25 years of theoretical operating state and production of energy without damaging our planet. All great on paper, right? Sure, if the maintenance of the PV plant is done properly.
There are different factors that can lead PV panels to less or more significant deterioration, thus the loss of energy production. We’ve already seen last month the classification of thermal anomalies that our team uses to diagnose the panels with. Whilst some of them can’t be identified with the naked eye (i.e. Extended, Strings, Diode – all correlated to internal wiring, electrical mismatches and connectors issues), the other ones you can easily spot just by looking at the modules’ surface and adjust your maintenance activities properly to solve or avoid further problems that may arise.
Ethylene-vinyl acetate (EVA) is a copolymer commonly used as an encapsulant of the PV panels. It comes with a series of advantages in mass production. Just to name a few: it’s relatively cheap, has a good light transmittance, low processing temperature, excellent melt fluidity, and adhesive property. On the other hand, though, it has its downside too. EVA is prone to degradation and questionable resistance to ultraviolet radiation which will make EVA decompose to produce acetic acid, thereby lowering the pH and generally increasing surface corrosion rates.
This phenomenon can affect single cells, its edges and busbars, and prevent the light from penetrating properly due to yellow or brown discolouration of the surface. On a thermal camera it appears as hotspots.
Although the front glass is thought to last long, it unfortunately isn’t bulletproof. In fact, cheaper panels might be affected by cracking during the manufacturing process or even the transportation or installation practices. The weather plays a big role too: intense storms, hail or extreme cold can also create cracks.
Depending on dimension and severity, cracks can lead to significant energy losses by preventing a portion of light from reaching the cell and by exposure to weather conditions: if that is the case, the decrease of cell performance translates directly into thermal hotspots.
Even if the crack does not affect the production of the cell, its visual detection and management can prevent its degradation and, therefore, future energy losses like those mentioned above.
Debris, Soiling & Shadowing
When a PV plant is exposed to natural factors, dealing with fallen objects, dirt, dust and plants or even trees creating shadows onto the panels is inevitable. In terms of maintenance, maybe it’s the easiest way to solve potential issues translated mostly into hotspots (both single and multiple) by keeping the cleaning scheduled with regularity.
Any type of overlayed substances or objects sitting on top of the PV panels keep them from absorbing the sunlight properly. Furthermore, if there are cracks already present on the surface, they can get dust and dirt penetrating the front glass and lead to serious issues with the cells and overall performance of the panel.
Delamination is the first example of a mechanical anomaly that isn’t visible in thermal imagery (except extreme cases in which water infiltrates underneath EVA and causes a direct overheating response, easily detectable with a thermal camera).
What causes delamination, you may ask? Delamination is nothing more than the detachment of the laminated components. It often starts as a manufacturing defect or inaccurate installation within the module trim. Once the external layers, usually along the borders, start to lift, bubbling and moisture infiltration may occur. This leads to potential corrosion on the metal conducting part of the panel, thus decrease of panel’s energy production.
In conclusion, I would say you should keep an eye on your panels. Even the smallest crack that gets neglected could cause major energy losses, and lead to permanent structural damage, or even hazardous fires.
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