Warning: Your PV Module Might Just Lose Power Suddenly

PID Effect
Image source: EcoGeneration

You have signed up for a solar PV installation package. You are happy that the price is one of the cheapest in town. The system integrator happily tells you about your expected yield for the next 21 years. Then 2 years down the road, you notice that your FiT payment from TNB drops significantly. You ask the system integrator to examine the installation, everything looks good, yet nobody is able to determine what went wrong. Your FiT payment becomes lower and lower. Your ROI has to be extended for another 3 to 5 years. So you have no choice but to accept the defeat, accepting the fact that you are one of the unlucky ones. Isn’t that sad news? Well, actually there is a term for such inexplicable performance loss and the PV community has largely acknowledged such failure. It is called Potential Induced Degradation (PID).

So what is PID? PID in layman’s terms, is power loss as a direct result of  potential current “jumping” across the semiconductor material within the PV module to the other components and elements of the  PV module itself  namely glass, frame and mounting structure. PID is accelerated  primarily by increasing humidity and heat with reference to system voltage. That means if your module is not PID proof and there is no proper anti-polarization measures installed, you are going to suffer from progressive performance losses up to 20% or even more in a system’s yield, especially in tropical countries with high heat and humidity like Malaysia.

However, corrective and preventive measures are taken by the leading PV module and inverter manufacturers such as Solon, Advanced Energy, Q Cells and SMA, so PID can basically be prevented on:

  1. Cell level
  2. Module level
  3. System level

As one of the international testing and certification bodies, UL has also produced the latest testing for PID susceptibility.
UL PID Test Procedure
Imaged adapted from: UL

So next time make sure you ask the system integrators if their modules are PID free. If they can’t produce any proof to show that their modules are PID resistant, it is better for you to engage someone else that does rather than swallowing the risk all by yourself.

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