How Does Light-Induced Degradation Reduce Efficiency of Silicon Solar Cells? Scientists Explore This Problem

Scientists from the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) and Colorado School of Mines are applying a novel technique to probe light-induced degradation (LID) in silicon solar cells.

Several research groups have already studied (LID) in solar cells before, but no one has been able to describe the exact microscopic nature of what causes the degradation. Scientists said that studying the mechanism behind LID in silicon solar cells could lead to improvements to strengthen their products and improve efficiency.

LID Shaves Off Efficiency of Silicon Solar Cells

According to NREL, LID decreases the efficiency of silicon solar cells by about 2% that makes it drop power output after 30 to 40 years of being deployed in the field.

Currently, silicon solar cells make up over 96% of the global market. PV Magazine reported that the semiconductor used in manufacturing them is mostly made up of boron-doped silicon. However, boron-doped silicon is susceptible to LID, which means that manufacturers have developed a technology to stabilize the solar cells to avoid damage.

Study lead author Abigal Meyer, a Ph.D. candidate at Mines and an NREL researcher, said that some of the modules are completely stabilized, but some are only half-stabilized. Understanding LID at the atomic levels could help scientists to predict the stability of solar modules created to avoid LID.

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Microscopic Examination Revealed Defect Signature in Solar Cells

Scientists from NREL and Colorado School of Mines collaborated to conduct the study titled "Light-induced Degradation of Silicon Solar Cells with Aluminiumoxide Passivated Rear Side," published in the journal Energy & Environmental Science.

The study involves using electron paramagnetic resonance (EPR) to identify the defects responsible for LID. Through microscopic examination, they were able to detect the distinct defect signature in a sample of silicon solar cells that became degraded the longer it is exposed to light.

The team observed that the defect signature disappeared when they applied the empirical "regeneration" process to cure LID. This is a similar process that the industry of making solar cells have been using.

They found that light exposure affected EPR signature, which involves many dopant atoms than there are defects caused by LID. Researchers hypothesize that LID might not cause all atomic changes.

Moreover, the team noted that their technology in studying LID could be extended to also look for other types of degrading defects in silicon solar cells and semiconductor materials used in manufacturing solar cells and photovoltaic, such as cadmium telluride and perovskites.

In conclusion, researchers said that indirect experimentation and their theory showed that the problem with LID in solar cells decreases when less boron is used and less oxygen is present in the silicon.

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