Media release

From: The University of New South Wales

KEY FACTS:

• The global solar photovoltaic (PV) market has reached 1 terawatt of power output in 2022. However, to power the earth using 100% renewables by 2050, we need as high as 60 TW from PV. When we increase the capacity by this much, we need to think about material sustainability, including abundant materials.

• Crystalline silicon based PV has dominated 95% of the market in the last 5 years, with most electricity generation from solar PV coming from monocrystalline-silicon based passivated emitter and rear contact (PERC) solar cells.

• Polysilicon is a high-purity form of silicon, which is a key raw material in the crystalline silicon photovoltaic (PV) technology. To produce solar modules, polysilicon is melted at high temperatures to form ingots typically using Czochralski monocrystalline, which are then sliced into wafers and processed into solar cells and assembled into solar modules. Last year alone, about 30 billion silicon wafers were produced for 191 GW. Considering how much more will need to be produced to meet 100% renewable energy, the silicon demand will continue to increase exponentially.

• A solar cell is made up of two layers that are treated to let electricity flow through them when exposed to sunlight. One layer is positively charged, the other negatively charged. As photons enter the layers, they are absorbed and separated into electrons and holes in the absorber layer, electrons then flow through the connected wires to generate current before they are collected.

• In order to meet the increased demand for solar power across the world required to replace energy generated by fossil fuels, a huge increase in the production of solar panels will be needed, using up to 6-7 megatonnes (Mt) per year or cumulative amount of 46-87 Mt of polysilicon in 2050 under a broad electrification scenario. This in turn means that industry needs to immediately work towards a sustainable model of polysilicon production. This paper offers some pathways forward.

AUTHORS:

Brett Hallam, Moonyong Kim, Robert Underwood, Storm Drury, Li Wang, Pablo Dias.

Researchers at the School of Photovoltaic and Renewable Energy Engineering (SPREE) at UNSW, Sydney, have conducted a wide-ranging review of global consumption trends and usage predictions of the material polysilicon used in solar cells, to be published with Solar RRL. In the paper, the researchers conclude from the data that there will be supply pressures placed on global reserves of polysilicon as the manufacture and deployment of solar panels increases across the world, and that future deployment of low-cost PV will require close monitoring of silicon consumption to ensure polysilicon production can grow proportionately with demand without the supply issues that have been seen in the past. To endure this, large expansions in the production capacity of polysilicon will be required in the near future, along with other supporting materials and infrastructure. The authors also look to environmentally sustainable practices in the production of polysilicon.

“We're so pleased to be able to bring awareness to the issue of critical material sustainability within the PV industry,” said SPREE researchers Moonyong Kim and Sophie Burrage, “and as we move into this projected terawatt capacity age of solar, our hope with this is work is to bring awareness that with this significant growth we need to plan now to ensure the renewables transition will be sustainable and environmentally responsible.”