News
What Is PID (Potential-Induced Degradation)? Why Does It Greatly Impact Solar PV Efficiency?
- November 19, 2025
Potential-Induced Degradation (PID) is one of the most critical degradation mechanisms affecting photovoltaic (PV) systems. It can significantly reduce a solar panel’s power output—sometimes by 20–80%—if not properly addressed. As solar systems become larger and more widespread, understanding PID is essential for ensuring long-term performance and investment stability.
This article explains what PID is, why it happens, and how it affects solar efficiency, along with solutions used in modern PV and energy storage systems to prevent it.
What Is PID (Potential-Induced Degradation)?
PID is a degradation effect that occurs when high voltage differences exist between PV cells and the grounded frame of the module. These voltage stresses cause leakage currents, leading to ion migration (usually sodium ions) from the glass into the solar cells.
This migration damages the cell structure and reduces its ability to convert sunlight into electricity.
In simple terms:
PID happens because voltage stress forces unwanted electrical currents to flow where they should not, weakening the solar panel over time.
What Causes PID?
PID is triggered by a combination of electrical, environmental, and material factors. The most common causes include:
1. High System Voltage
Large PV systems (1000V or 1500V) are more prone to PID because the potential difference between the solar cells and the grounded frame increases ion movement.
2. Humidity and Moisture
Moist environments accelerate ion migration, especially in poorly encapsulated panels.
3. High Temperature
PID becomes more severe at higher temperatures, making hot climates more vulnerable.
4. Material Vulnerability
Lower-quality encapsulants, glass, or cell materials are more sensitive to PID.
5. Negative Polarity to Ground
PID is most common when the PV module operates at a negative potential relative to the ground.
How Does PID Affect Solar Efficiency?
PID has a direct and severe impact on solar performance:
● Significant Power Loss
PID can reduce module power output by 20% in months, and in extreme cases more than 50–80%.
● Lower Cell Voltage and Current
Ion contamination changes the cell’s electrical properties, reducing:
open-circuit voltage (Voc)
short-circuit current (Isc)
● Reduced Energy Yield
PID-stricken panels underperform daily, lowering the overall system energy yield and ROI.
● Accelerated Aging
Panels with PID degrade faster and have a shorter effective lifespan.
● Hot Spots and Reliability Issues
PID increases the risk of:
cell mismatch
thermal stress
long-term reliability failures
For commercial and utility-scale solar farms, PID is one of the biggest hidden threats to long-term profitability.
How to Detect PID?
PID can be identified through:
Infrared (IR) thermography (detecting hot spots)
Electroluminescence (EL) imaging
I-V curve analysis
Daily energy performance monitoring
Modern AI-based monitoring systems can also detect early PID patterns before severe damage occurs.
How to Prevent or Mitigate PID
PV system designers and operators use several methods to prevent PID:
1. Use PID-Resistant Modules
Tier-1 manufacturers now use PID-resistant:
glass
EVA encapsulants
cell structures
2. Maintain Proper System Grounding
Correct grounding reduces voltage stress between the cell and the frame.
3. Install a PID Recovery or Anti-PID Device
These devices apply a reverse voltage at night to:
stop PID progression
partially recover lost performance
4. Improve Environmental Protection
Better sealing, proper installation, and avoiding high-humidity environments help reduce PID risk.
5. Smart Monitoring with EMS + AI
Advanced EMS systems—like those integrated with energy storage—can:
detect PID early
adjust system polarity
limit operational conditions that accelerate PID
Why PID Matters for Solar + Energy Storage Systems
For hybrid PV + ESS systems, PID has a direct effect on:
● Overall Energy Production
Less solar generation means less energy for storage.
● Battery Utilization
More frequent charging cycles may be needed to meet load demand, increasing battery wear.
● Project ROI
Lower solar output directly reduces the economic performance of the entire system.
Ensuring PID-free operation is therefore essential for maximizing long-term savings and system efficiency.
Conclusion
PID is a major degradation issue that can severely impact the performance and financial return of solar PV systems. By understanding its causes and adopting PID-resistant technologies, proper grounding, and smart system monitoring, PV operators can ensure long-term reliability and efficiency.
As the solar industry moves toward higher voltages and larger installations, effectively managing PID becomes more important than ever.