Comparing Environmental Impacts of Single-Junction Silicon and Silicon/Perovskite Tandem Photovoltaics–A Prospective Life Cycle Assessment

Tandem photovoltaics applying perovskite on silicon are
considered
to be a possible route to sustaining continuous efficiency improvements
and price reductions. A meaningful market share for such tandems is,
however, at least a decade away. Herein, a comprehensive prospective
life cycle assessment was conducted, comparing the full life cycle
of monofacial and bifacial silicon/perovskite tandem panels with single-junction
silicon panels produced up to 2050. The end-of-life included the recovery
of silicon and silver. Climate change impacts per kilowatt hour were
projected to decrease by two-thirds over time. Tandem panels are expected
to reach impacts of 8–10 g CO2-eq/kWh in 2050, while
single-junction panels may reach 11–13 g CO2-eq/kWh
in 2050. Other midpoint impact categories with substantial contributions
to damaging human health and ecosystem quality were toxicity, particulate
matter formation, and acidification, with tandems having lower impacts
in each category. Reductions in impacts over time are mainly the result
of grid mix decarbonization and panel efficiency improvements. Balance-of-system
and recycling were found to contribute substantially to these impact
categories. To ensure that tandem panels provide environmental benefits,
annual degradation rates should not exceed 1% for monofacial or 3%
for bifacial tandems, and refurbishment of panels with advanced degradation
is crucial.