Silicon PV: Traditional and PI Energy’s Process Comparison

Traditional silicon PV energy intensity:

About 96% of solar PV modules use silicon, and this traditional manufacturing process is dominated by fabrication facilities in East Asia, many of which are located near coal mines to meet power and supply requirements.

Traditional Silicon PV Supply Chain (partial & simplified, image and data sources: NREL, 2018; and NATO, 2021)

Silicon makes up about 25% of the earth’s crust, but traditional solar-grade silicon has to be extremely pure, often over 99.9999% pure, which currently entails long, complex, and very energy intensive steps. Coal and charcoal are also used to refine silicon precursors to make polysilicon, further contributing to overall emissions of the traditional PV. The current solar industry uses the Siemens Process and Fluidized Bed Reactors, followed by the Czochralski Process, to refine and purify, producing monosilicon (single crystal) ingots, with process temperatures over 2,500° F. The ultra-pure monosilicon ingot is then sliced, creating the wafers upon which traditional solar cells are built, and further assembled into modules.

Czochralski crystal growth: from polysilicon meltdown to monosilicon ingot (“Silicon Crystal Growth and Wafer Technologies”, Fisher et al, 2012)

 PI Energy’s solution:

Instead of sawing crystal ingots, PI Energy's technology uses deposition processes, allowing us to use flexible substrates, resulting in a silicon PV layer that is extremely thin and lightweight - with less than 2% of the silicon contained in traditional PV. Our proprietary technology utilizes low-temperature fabrication, entirely avoiding traditional energy-intensive Siemens Process, Fluidized Bed Reactors, and Czochralski Process. This further decreases the energy intensity and provides a far more efficient path to solar PV manufacturing. 

Lowering the energy intensity of solar PV fabrication is critical to making solar energy far more profitable, competitive, sustainable and globally scalable.