3260
Major Barriers and Recent Progress in
Silicon Solar Module Recycling
Meng Tao, Theresa Chen, Natalie Click, and Randall Adcock
School of Electrical, Computer, and Energy Engineering, Arizona State University, Tempe, AZ, USA
ABSTRACT: Current state-of-the-art recycling technologies for silicon solar modules employ only physical
methods to recover aluminum frame, junction box (for copper wires), and glass. With glass recovered for new
glass products, about 90% of the materials in silicon modules by weight (wt%) are recovered for reuse. However,
the recovered aluminum, copper, and glass generate only about $4/module in revenue, while the remaining
10 wt% of the module contains about $6/module in additional revenue, which includes silver, lead, silicon,
tin, and more copper in silicon solar cells. Their recovery requires chemical methods. Major technical barriers
to chemical recycling of silicon cells include: 1) removal of the fluoropolymer back sheet 2) removal of the
encapsulant on silicon cells and 3) minimization of the quantity and hazard of the chemicals along with
high material recovery rates. Noticeable progress in silicon cell recycling includes: 1) laser debonding of the
encapsulant from silicon cells 2) dissolution of the encapsulant with a base 3) mild chemicals for silver and lead
recovery and 4) regenerative chemistry to reuse some of the chemicals in silicon cell recycling.
INTRODUCTION
The amount of end-of-life solar modules can be estimated
from the historical data on annual installation of solar
modules. In 2022, the global annual installation of solar
modules reached 239 gigawatts peak or GWp (SolarPower
Europe, 2023). Most module manufacturers guarantee a
lifetime of 25 years for their modules, so we could expect
239 GWp of end-of-life solar modules in 2047. As a typical
300 Wp solar module weighs about 18 kg, the 239 GWp
of solar modules amount to 14 megatonnes (Mt) of solar
waste in 2047. This number exceeds the projection of 8–10
Mt/year by the International Renewable Energy Agency
(International Renewable Energy Agency, 2016).
The actual amount of end-of-life solar modules could
be even higher than 14 Mt/year in 2047. Although the
rated lifetime of solar modules is 25 years, the actual life-
time of a solar module could be significantly shortened in
multiple scenarios such as damage during shipping and
installation, weather conditions such as storms and floods,
rapid component degradation and failures, or simply the
economic incentive of replacing older modules with newer
higher-efficiency ones. Manufacturers’ warranties cover
only component degradation and failures. There is mount-
ing anecdotal evidence for significant early decommission-
ing, e.g., from a study in Australia (Florin et al., 2020) and
through conversations with the Solar Energy Industries
Association and owners of utility-scale solar farms. The
average annual growth of the solar industry in the last 20
years is over 30%. If the industry maintains a 30% annual
growth rate over the next few years, end-of-life solar mod-
ules could add up to 30 Mt/year in 2050.
Silicon solar modules have been the dominant technol-
ogy in the solar industry for decades, with a market share
of 97% in 2022 (International Energy Agency, 2023a). To
achieve a circular economy in the solar industry, a 90–95%
circularity by weight (wt%) for silicon modules is required.
That is, 90–95 wt% of the materials contained in silicon
modules are recovered for reuse in new modules. This paper
Major Barriers and Recent Progress in
Silicon Solar Module Recycling
Meng Tao, Theresa Chen, Natalie Click, and Randall Adcock
School of Electrical, Computer, and Energy Engineering, Arizona State University, Tempe, AZ, USA
ABSTRACT: Current state-of-the-art recycling technologies for silicon solar modules employ only physical
methods to recover aluminum frame, junction box (for copper wires), and glass. With glass recovered for new
glass products, about 90% of the materials in silicon modules by weight (wt%) are recovered for reuse. However,
the recovered aluminum, copper, and glass generate only about $4/module in revenue, while the remaining
10 wt% of the module contains about $6/module in additional revenue, which includes silver, lead, silicon,
tin, and more copper in silicon solar cells. Their recovery requires chemical methods. Major technical barriers
to chemical recycling of silicon cells include: 1) removal of the fluoropolymer back sheet 2) removal of the
encapsulant on silicon cells and 3) minimization of the quantity and hazard of the chemicals along with
high material recovery rates. Noticeable progress in silicon cell recycling includes: 1) laser debonding of the
encapsulant from silicon cells 2) dissolution of the encapsulant with a base 3) mild chemicals for silver and lead
recovery and 4) regenerative chemistry to reuse some of the chemicals in silicon cell recycling.
INTRODUCTION
The amount of end-of-life solar modules can be estimated
from the historical data on annual installation of solar
modules. In 2022, the global annual installation of solar
modules reached 239 gigawatts peak or GWp (SolarPower
Europe, 2023). Most module manufacturers guarantee a
lifetime of 25 years for their modules, so we could expect
239 GWp of end-of-life solar modules in 2047. As a typical
300 Wp solar module weighs about 18 kg, the 239 GWp
of solar modules amount to 14 megatonnes (Mt) of solar
waste in 2047. This number exceeds the projection of 8–10
Mt/year by the International Renewable Energy Agency
(International Renewable Energy Agency, 2016).
The actual amount of end-of-life solar modules could
be even higher than 14 Mt/year in 2047. Although the
rated lifetime of solar modules is 25 years, the actual life-
time of a solar module could be significantly shortened in
multiple scenarios such as damage during shipping and
installation, weather conditions such as storms and floods,
rapid component degradation and failures, or simply the
economic incentive of replacing older modules with newer
higher-efficiency ones. Manufacturers’ warranties cover
only component degradation and failures. There is mount-
ing anecdotal evidence for significant early decommission-
ing, e.g., from a study in Australia (Florin et al., 2020) and
through conversations with the Solar Energy Industries
Association and owners of utility-scale solar farms. The
average annual growth of the solar industry in the last 20
years is over 30%. If the industry maintains a 30% annual
growth rate over the next few years, end-of-life solar mod-
ules could add up to 30 Mt/year in 2050.
Silicon solar modules have been the dominant technol-
ogy in the solar industry for decades, with a market share
of 97% in 2022 (International Energy Agency, 2023a). To
achieve a circular economy in the solar industry, a 90–95%
circularity by weight (wt%) for silicon modules is required.
That is, 90–95 wt% of the materials contained in silicon
modules are recovered for reuse in new modules. This paper