Why are photovoltaic panels "in a bad mood"? Is this a "disease"?

With the continuous expansion of photovoltaic applications, N-type high-capacitance Photovoltaic Modules have become the new favorite in the market. Users occasionally report that the power performance of the modules has "abnormal fluctuations" or "sudden attenuation" phenomena, which may raise questions about the product quality. However, such phenomena are often not defects in the modules themselves. The reasons usually come from two common but easily misunderstood phenomena - UVID (Ultra-Violet Induced Degradation) and metastable power changes, which are the normal reactions of the inherent physical properties of photovoltaic modules in actual environments.

Why are photovoltaic modules "in a bad mood"?
With the continuous expansion of photovoltaic applications, N-type high-capacitance photovoltaic modules have become the new favorite in the market. Users occasionally report that the power performance of the modules has "abnormal fluctuations" or "sudden attenuation" phenomena, which may raise questions about the product quality. However, such phenomena are often not defects in the modules themselves. The reasons usually come from two common but easily misunderstood phenomena - UVID (Ultra-Violet Induced Degradation) and metastable power changes, which are the normal reactions of the inherent physical properties of photovoltaic modules in actual environments.
But the ultraviolet rays emitted by the sun are like a group of high-energy "violent wall demolition workers" who specifically pick "wall bricks" (hydrogen-silicon bonds) and smash them, causing holes in the protective layer and reducing the efficiency of the battery. At the same time, ultraviolet rays will "drive away" the metal impurities in the battery, causing them to gather in other places and form "trouble centers". In this way, the power generation capacity of the component will deteriorate. From the appearance, some places are bright and some places are dark, just like being sick. This is the UVID phenomenon.

If the component is placed indoors at this time, problems will also occur when it is out of the light environment. Without light, it is like there is no "energy supply", the electrons become less, and the protective ability of the aluminum oxide "protective clothing" also weakens. The power generation power of the solar panel will continue to decline. This is the metastable phenomenon.

This is not a "disease"
Most of these phenomena are temporary, and their essence is the manifestation of "components adapting to the environment" rather than quality problems.
Research has found that as long as the photovoltaic components are exposed to the sun again, they can gradually restore their original performance. In layman's terms, if ultraviolet rays are "wall demolition workers", then sunlight is the "rescue team". Although ultraviolet rays are "demolishing walls", the sun's "rebuilding" speed is faster. As long as the light is maintained and the components are "charged", the electrons generated by the light will drill into the gaps in the alumina "protective coat", enhance its protective ability, stabilize the surface of the battery again, and the power generation and appearance will return to normal. Even if it is illuminated by a device that simulates sunlight, it can quickly get better.

After research, the professional organization TÜV Nord found that UVID and metastable phenomena have little effect on the actual total power generation of components outdoors. In other words, the occasional "little temper" of the components is actually a recoverable temporary attenuation. The outdoor components are "repairing while being injured" every day (UVID damage is repaired in real time by light), and the long-term power generation is almost unaffected.

How to identify and solve
More and more experts and companies are studying UVID and metastable phenomena. In 2025, the international community has begun to discuss relevant standards, requiring that before the power generation of photovoltaic components is marked, the relevant factors of these phenomena must be considered. In China, the China Photovoltaic Association is also organizing industry experts, manufacturers, and testing institutions to participate in the discussion and formulation of unified standards.

The initial fluctuations during the operation of the components are the natural process of the photovoltaic system "moving from static to dynamic". Understanding these physical phenomena will help the industry establish a more rational and scientific quality cognition, and also help the project party make more accurate operation judgments and operation and maintenance strategies. Although many friends at the terminal do not understand this kind of phenomenon, with the joint efforts of the industry, these phenomena will be studied and solved like other technical problems, making photovoltaic power generation more stable and reliable.