What is the PID (Potential Induced Degradation) effect of solar panels?

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Installing solar panels is a long-term investment. A one-time purchase can provide customers with a continuous supply of electricity. The average lifespan of crystalline silicon solar panels currently available is 25-30 years. So, what factors influence the lifespan of solar panels? The efficiency of photovoltaic cells, for example, will decrease over time; however, another factor that cannot be overlooked is the PID effect.


What is PID effect of solar panels?​

When components operate at high voltage for an extended period of time, the PID effect, also known as Potential Induced Degradation, occurs. This may result in a current leakage between the cover glass, solar panel encapsulation material, and frame. Positive ions move from the glass, frame, and installation structure to the solar photovoltaic cell due to the difference in electrical charge. When a large amount of charge accumulates on the cell's surface, it can damage the PN junction. The passivation effect on the cell's surface worsens, resulting in lower fill factor, short-circuit current, and open-circuit voltage. This reduces the component's performance below what was intended, resulting in a drop in overall performance.

PID effect of solar panels

What is the reason for PID effect in solar panels?

The quality of raw materials used for solar panels: The quality of solar panel raw materials such as glass, sealants, and solar panel encapsulation materials has a significant impact on whether the solar panel will experience the PID effect. For example, if a glass with a high sodium content is used, or if the solar panel encapsulation material used cannot prevent water vapor from entering, the PID effect in the solar panel can occur.

Solar panel installation locations: High temperature and humidity are the primary environmental factors that cause the PID effect. The impact of a solar power project on the solar panels is determined by where it is installed. Moisture will penetrate the solar panel module due to humidity, causing an increase in leakage current, a process that is accelerated at high temperatures and affects solar panel yield.

Solar panel system voltage and scale: In general, the more panels connected in series, the higher the system voltage, and the higher the stray current or leakage current generated when there is a potential difference between solar photovoltaic cells and the ground, resulting in The likelihood of the PID phenomenon is greater. In general, 1500 V systems are more vulnerable than 1000 V systems.

PID effect

How can the anti-PID performance of solar panels be tested before they leave the factory

1. Cover the surface of the module glass with aluminum foil, copper foil, or a damp cloth at a specific temperature and humidity, and apply a voltage between the module's output terminal and the surface covering for a set period of time.

2. Apply -1000V DC to the module's output terminal and the aluminum frame for 96 hours in an 85°C, 60°C, or 85°C environment with 85% humidity.

The components are tested for power, wet leakage, and EL imaging before the two methods of testing. After that, the power, wet leakage test, and EL imaging are repeated. To determine the occurrence of PID under the specified conditions, compare the results before and after the test. When the PID phenomenon occurs, the EL imaging shows that some cells are blackened.

The first method is mostly used in research institutions, whereas the latter is mostly used by solar panel manufacturers. In fact, the ultimate goal of the two test methods described above is to obtain PID resistance certification for the solar panel test module - IEC 62804.

Maysun Solar's solar panels are certified by Solar Panel Test Module PID Resistance - IEC 62804, ensuring excellent quality.

anti-PID performance
Twisun 390W--410W Double Glass Full Black PV module PERC 210mm 120cells
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How to avoid the PID effect in the use of solar panels?

Depending on what caused it, the PID effect can be reversible or irreversible. Unfortunately, PID (potential-induced degradation) is unavoidable when caused by internal electrochemical reactions. Thin film delamination or galvanic corrosion in photovoltaic panels can result from this. There are ways to avoid and solve the PID effect if it is caused by external factors.

anti  PID effect

1. Use a PID-preventing device. The anti-PID box is a device that changes the direction of the inverter's electrical current. This helps to mitigate the negative effects of voltage on PV modules. The purpose of these boxes is to keep each string from remaining on the same polarization for an extended period of time. This reduces the possibility of PID (potentially induced degradation) and allows each module to recover from any negative potential.

broken image

2. Creating a functional and logical installation system. High temperatures can be detrimental to photovoltaic power plants. This problem, however, can be solved by implementing a well-planned system installation. Ensure that components, inverters, and distribution boxes have proper ventilation and heat dissipation capabilities. Furthermore, if the inverter allows it, you can solve the problem by grounding the inverter's DC negative terminal.

solar panel encapsulation

3. Choosing an efficient solar panel encapsulation method. The PID effect can be caused by humidity. You can prevent water vapor from entering and causing a reaction that produces acetic acid in the EVA film by using proper solar panel encapsulation. This acid then reacts with alkali on the glass surface, releasing sodium ions into the air. This contributes to the effective prevention of the PID effect.

Solar panel manufacturers have their own testing systems to make sure they consistently produce high-quality solar panels. Maysun Solar has been producing solar panels for the past 15 years. They have a wealth of knowledge in this field. They offer high-quality solar panels that are certified to resist PID (Potential Induced Degradation). This means that they meet the needs of users who want to use clean energy.

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