  Adopting thin Si wafers for PV reduces capital expenditure (capex) and
manufacturing cost, and accelerates the growth of PV manufacturing. There are
two key questions about thin Si today: (a) how much can we still benefit
economically from thinning wafers? (b) what are the technological challenges to
transition to thin wafers? In this work, we re-evaluate the benefits and
challenges of thin Si for current and future PV modules using a comprehensive
techno-economic framework that couples device simulation, bottom-up cost
modeling, and a cash-flow growth model. When adopting an advanced technology
concept that features sufficiently good surface passivation, similarly high
efficiencies are achievable for 50-um wafers as for 160-um ones. We then
quantify the economic benefits for thin Si wafers in terms of poly-Si-to-module
manufacturing capex, module cost, and levelized cost of electricity (LCOE) for
utility PV systems. Particularly, LCOE favors thinner wafers for all
investigated device architectures, and can potentially be reduced by more than
5% from the value of 160-um wafers. With further improvements in module
efficiency, an advanced thin-wafer device concept with 50-um wafers could
reduce manufacturing capex by 48%, module cost by 28%, and LCOE by 24%.
Furthermore, we apply a sustainable growth model to investigate PV deployment
scenarios in 2030. It is found that the state-of-the-art industry concept could
not achieve the climate targets even with very aggressive financial scenarios,
therefore the capex reduction benefit of thin wafers is needed to facilitate
more rapid PV growth. Lastly, we discuss the remaining technological challenges
and areas for innovation to enable high-yield manufacturing of high-efficiency
PV modules with thin Si wafers.
