{"id":34449,"date":"2026-02-19T09:53:46","date_gmt":"2026-02-19T08:53:46","guid":{"rendered":"https:\/\/biblus.accasoftware.com\/en\/?p=34449"},"modified":"2026-02-19T09:53:50","modified_gmt":"2026-02-19T08:53:50","slug":"pid-fotovoltaico-potential-induced-degradation","status":"publish","type":"post","link":"https:\/\/biblus.accasoftware.com\/en\/pid-fotovoltaico-potential-induced-degradation\/","title":{"rendered":"PID Potential Induced Degradation: Photovoltaic Degradation"},"content":{"rendered":"

PID photovoltaic is a potential degradation phenomenon of photovoltaic modules caused by the difference in voltage. Discover the causes and how to prevent it<\/p>\n

<\/p>\n

PID photovoltaic (potential induced degradation<\/strong>) is an electrical phenomenon that causes a loss of power in photovoltaic modules<\/strong>. This phenomenon manifests itself over the course of several months or even years: in fact, it is often overlooked at the beginning of the plant’s life, while it becomes more burdensome in the later stages of operation, especially because it is not always easy to trace the causes.<\/p>\n

The effects of PID can be reversible and irreversible. These performance degradation effects on the module and system can result in significant changes to the plant’s business plan. In particular, cases of PID have been reported that led to a power reduction of up to 70% in less than a year.<\/p>\n

It is, therefore, essential to constantly monitor the photovoltaic system in order to identify the first signs of performance degradation present in the system. To this end, in order to obtain economic analyses regarding the actual profitability of the plant, you can use the photovoltaic software<\/a>.<\/p>\n

Let us analyze in detail what causes PID photovoltaic, its effects, and the strategies to identify and prevent it.<\/p>\n

\"photovoltaic

What is potential induced degradation (PID) in photovoltaic panels?<\/h2>\n

Potential induced degradation, known by the acronym PID (Potential Induced Degradation)<\/strong>, is a phenomenon that can affect photovoltaic modules when they are subjected to significant differences in electric potential relative to the ground or the support structure of the system. This phenomenon leads to a reduction in the photovoltaic effect<\/strong>, resulting in a decrease in the power of photovoltaic cells<\/a>. Advanced systems with bifacial photovoltaic panels<\/a> can be particularly sensitive to PID due to their dual-sided structure, which requires careful design and monitoring.<\/p>\n

PID occurs when a high difference in electric potential<\/strong> develops between the cell, which constitutes the active semiconductor material, and other parts of the module, such as the glass, support, or aluminum frame. This condition is typical of photovoltaic systems connected in high-voltage strings.<\/p>\n

The potential difference generates a leakage current<\/strong> within the module, which facilitates the migration of ions. Negative ions tend to disperse towards the aluminum frame, while positive ions, particularly sodium ions present in the glass, migrate towards the surface of the cell. The accumulation of these ions alters the electrical properties of the cell, compromising the proper functioning of the photovoltaic effect and causing power losses.<\/p>\n

The degradation is progressive over time and can manifest even in the first few months of the system\u2019s operation, especially in unfavorable environmental conditions, such as high humidity and high temperatures.<\/p>\n

The phenomenon of PID can affect the various types of photovoltaic panels<\/a> and is not related to an isolated manufacturing defect, but to the overall behavior of the photovoltaic system<\/strong>, which involves modules, inverters, grounding schemes, and operating conditions. For this reason, it represents a significant issue both at the design stage of the system and during operation and maintenance.<\/p>\n

Types of PID: reversible and irreversible<\/h2>\n

Potential induced degradation can manifest in different forms depending on the intensity of the phenomenon, the duration of exposure, and the construction characteristics of the photovoltaic module. Based on the effects produced on the cells and the possibility of recovering performance, PID is generally distinguished into reversible<\/strong> and irreversible<\/strong>.<\/p>\n

Reversible PID (polarization)<\/h3>\n

This is the less severe form of potential induced degradation. The performance loss is mainly due to the temporary accumulation of charges<\/strong> or ions<\/strong> on the surface of the cells and the presence of leakage currents through the encapsulation material, the frame, and the front glass.<\/p>\n

This type of PID is particularly evident in the modules positioned at the bottom of the photovoltaic strings, i.e., those closest to the negative pole, where power loss can reach up to 70% in a few years.<\/p>\n

If the cause of the phenomenon is removed, for example by reducing the potential difference or intervening on the system configuration, the module can recover<\/strong> all or part of the original power. Reversible PID is more frequent in the initial operating phases of the system and is often counterable with appropriate technical solutions.<\/p>\n

Irreversible PID (electrocorrosion of the TCO layer)<\/h3>\n

This form of PID results in a deeper<\/strong> and permanent degradation of photovoltaic cells<\/strong>. Ionic migration and leakage currents cause structural or chemical damage, particularly to the TCO (Transparent Conductive Oxide) layer, which stably compromises the electrical properties of the cell.<\/p>\n

The phenomenon manifests especially when the frame comes into contact with moisture, triggering an electrochemical reaction that causes corrosion of the materials. In these cases, even if the cause of PID is eliminated, the performance of the module cannot be restored, making panel replacement<\/strong> or a significant reduction in performance expectations over time<\/strong> necessary.<\/p>\n

To limit or prevent irreversible PID, one can intervene on the choice of frame materials or use inverters with galvanic separation, reducing the potential differences responsible for the phenomenon.<\/p>\n

\"Types

Main Causes of PID in Photovoltaic Modules<\/h2>\n

The causes that lead to the onset of potential induced degradation (PID) in photovoltaic modules are numerous and depend both on the constructive characteristics of the module<\/strong> and the electrical operating conditions of the system<\/strong>. In particular, the main factors influencing PID are:<\/p>\n