UNSW says “gallium doping” generates cheaper, more stable solar panels


Gallium-doped silicon heterojunction solar cell. Image credit: UNSW

Research from the University of New South Wales’ (UNSW) School of Photovoltaics and Renewable Energy Engineering has shown that adding gallium to a solar cell’s silicon can produce more stable solar panels. 

The research was conducted by UNSW postdoctoral researcher in Photovoltaic Engineering, Matthew Wright; Scientia and DECRA fellow, Brett Hallam; and PhD candidate, Bruno Vicari Stefani. 

In the two million Australian rooftops that have solar panels, silicon is the main material used in their manufacture to convert sunlight into power. Two types of silicon are joined together to create electricity – otherwise known as “doping” – by forming a “p-n junction” to allow the solar cell to operate. 

Traditionally boron is used as one of the silicones. However, shining light on boron-filled silicon can degrade the quality of the silicon, which damages the solar panels over time. This reduces the amount of power generated by the solar panel. 

Enter gallium. The process of manufacturing gallium-doped solar panels was under a patent until May 2020, when the manufacturing industry shifted to using gallium as an alternative to boron. 

Since then, leading photovoltaic manufacturer Hanwha Q Cells has estimated that around 80 per cent of all solar panels manufactured in 2021 used gallium doping rather than boron. 

The UNSW researchers then studied whether gallium really did boost solar panel stability. 

“To find out, we made solar cells using a ‘silicon heterojunction’ design, which is the approach that has led to the highest efficiency silicon solar cells to date. This work was done in collaboration with Hevel Solar in Russia,” the researchers said. 

“We measured the voltage of both boron-doped and gallium-doped solar cells during a light-soaking test for 300,000 seconds. The boron-doped solar cell underwent significant degradation due to the boron bonding with oxygen. 

“Meanwhile, the gallium-doped solar cell had a much higher voltage. Our result also demonstrated that p-type silicon made using gallium is very stable and could help unlock savings for this type of solar cell.” 

Manufacturing solar cells with gallium at scale can produce more stable and potentially cheaper solar panels, creating a brighter future for the planet. 

For more detailed information about how gallium works and how it is being used to manufacture improved solar panels, click here.

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