PV Magazine reports that [
LINK] Researchers from Finland’s Aalto University and the Michigan Technological University, in the US, say they have demonstrated the cost per unit of power of black-Si PERC cells could fall 10.8%, despite an increase in cell processing cost. A new study in
Energies*, conducted by scientists from Finland’s Alto University and the U.S.-based Michigan Technological University, however, intends to show production costs for black-Si PERC cells may be reduced by around 10% even using dry-etching, a process for making solar cells more efficient at capturing light.
Detailed manufacturing steps for texturized Czochralski PERC cells (left) and multicrystalline black-Si PERC cells (right). The overall processes are divided into wafer production (Steps 1 to 3) and cell processing (Steps 4 to 14). Their cost represent 85% and 15% of the total costs for the texturized Czochralski and 82% and 18% for the multicrystalline black-Si PERC, respectively. The steps highlighted in blue differ for the two cell architectures and are considered in the cost calculations. (Figure from the Energies Article released under Creative Commons Licence CC BY 4.0*)
According to the study in Energies above, ALD is used for the surface passivation steps and show yet another potential cost saving, since the black mc-Si PERC can effectively be passivated with a double-side ALD step prior to capping the rear side by SiNx, leading to both lower process costs and a lower number of necessary processing tools. The cost for the surface passivation by double-sided ALD is <50% of the cost for the corresponding steps by PECVD and CVD for the standard Cz process, which also includes an additional back surface polishingstep.
Sum of the normalized costs for the PERC process steps that are different between the reference (standard texturized Cz-Si PERC) and the black mc-Si PERC. Step costs are normalized over the total steps costs for the reference device. The numbers on the black mc-Si PERC show the multiplying factor for each step in the process compared to the reference for the given process step. (Figure from the Energies Article released under Creative Commons Licence CC BY 4.0*)
However the study concludes that the largest challenge to escape the valley of death is the capital costs associated with PV industry-scaled RIE and ALD tools, which are both on the order of several million USD for a 1 GW PV plant. Therefore study recommend that governments can utilize to effectively assist industry in this respect by providing business incentive policies.
Scanning electron microscope image of reactive ion etched (RIE) black silicon [Wikipedia].
*Economic advantages of dry-etched black silicon in passivated emitter rear cell (PERC) photovoltaic manufacturing. Energies.
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