What is the PID effect on solar modules

PID can be understood as a sign of ageing.


The so-called PID (Potential Induced Degradation) of photovoltaic panels is an effect that affects the potential of the modules with respect to the ground and that affects the power of the module by reducing it consistently over time.


The main cause of PID is considered to be the high voltage between the encapsulated solar cells and the front glass surface, which is grounded through the frame or substructure.


This can lead to an unwanted migration of the charge carriers (ions / electrons), that reduces the performance of the cell. In case of high voltages due to long string connections, the PID effect can also occur more heavily. High humidity and temperature accelerate this process.


PID is a highly critical concern, because it generally only develops months after the installation of the photovoltaic system. And in addition to that, unlike other module defects (such as delamination or yellowing of EVA parts), the PID is not distinguishable with the naked eye.


What is the most important reference standard for the detection of PID-free modules?


The reference standard for modules is the IEC TS 62804-1: 2015 “Photovoltaic (PV) Modules – Test Methods for Detecting Potential Induced Degradation (PID)”.

In order to obtain “PID-free” certification in accordance with this standard, manufacturers must carefully select module components and optimize their production processes.


In PID tests, solar cells are exposed to exactly the conditions under which this phenomenon occurs: high temperatures and a high electrical potential between the glass surface and the solar cell. The test conditions are 60 °C (140 °F) ambient temperature and 85% humidity, with a negative potential of 1000 V for a duration of 96 hours. The cells must not show a power decrease of more than 5%.


For this purpose, aleo carries out extensive internal tests with even stricter criteria. For the approval of new module components, aleo is only permitted to degrade significantly less than specified in the standard. These internal quality controls have proved to be effective in external test laboratories, and aleo modules, which have passed the tests for years with a result of less than 1% performance degradation, have continued to improve.


PID-Free high-performance PV modules from aleo solar


In a series of PID tests conducted by Fraunhofer ISE in December 2019, no aleo module achieved a PID percentage greater than 0,68%.


aleo solar high-efficiency photovoltaic modules – PID Free


During the PID tests last December, the new aleo X63 panel even achieved an astonishing degradation rate of 0.37% of the output power.


From the Fraunhofer ISE report Dec. 2019 (FUE19700 V1):
Deviation of PMAX after the PID test with -1000V from the initial measurement.

Find our PID Certificate here: https://www.aleo-solar.com/app/uploads/sites/2/2020/01/COTR-2019-40636_20200114.pdf