Life Cycle Assessment of High-Efficiency Si Solar Modules

Abstract

A Life Cycle Assessment (LCA) is an analytical framework that quantifies the environmental impacts associated with the lifecycle stages of a product. This LCA compares the impacts of 1 kWh of electricity (functional unit) produced by two different hypothetical solar modules: a standard PERC crystalline silicon module and a luminescent solar concentrator (LSC)/PERC tandem module. An LSC-PERC tandem device contains luminescent materials that absorb incoming light with a wide frequency range and re-emits the energy as light in a narrow wavelength range that can be absorbed by silicon, increasing the module power conversion efficiency from 20% to 24%. This ‘cradle to grave’ LCA includes the following life stages: materials acquisition and module fabrication in China, transport to the hypothetical installation site in New Jersey, installation, use, electricity generated, maintenance, disassembly, and end of life. The results indicate that the tandem module will have less overall environmental impacts per unit of electricity generated than the PERC module. The carbon footprint calculated for the PERC module is 31.3 g CO2 eq/kWh, compared with 18.0 g CO2 eq/kWh for the Tandem module. Other impact categories analyzed include ozone depletion, smog, acidification, eutrophication, and human health effects. Several Sustainable Product Innovation (SPI) improvements were proposed and evaluated, including a reduction in the thickness of the silicon cells, replacement of virgin aluminum with recycled aluminum in the frames, removal of antimony in the formulation of the LSC device, and transfer of manufacturing from China to the USA. These SPIs further reduced the environmental impacts in the tandem modules and are reported on in this paper.