Increasing the climate benefit of photovoltaics (PV) by up to 208% points through low-carbon manufacturing

This study applies the absolute global warming potential (AGTP) metric to quantify temperature mitigation potential of low-carbon manufacturing of PV systems. The AGTP metric reveals that the manufacturing pulse greenhouse gas (GHG) emissions occurring earlier in the 30-year lifetime of a PV system will remain longer in the atmosphere within that lifetime and, thereby, induce a greater temperature increase than an equal mass of GHG emitted later in that timeframe. The AGTP metric quantifies the additional temperature benefit generated by low-carbon PV systems over a 30-year lifetime since low-carbon PV systems have lower upfront manufacturing emissions than high-carbon PV systems. The AGTP-based analysis quantifies the temperature benefits across silicon and CdTe PV manufacturing, six manufacturing electricity sources with varying GHG intensities and eight high and low-carbon manufacturing pathways to produce multi- and mono-crystalline silicon feedstock. While all PV provides net AGTP benefits over their 30-year lifetime, shifting from high to low-carbon PV manufacturing increases the net AGTP benefit by up to 208% points under US-average grid and solar insolation conditions. While low-carbon CdTe generates 170% greater net AGTP benefit than high-carbon mono-Si PV, this benefit diminishes to just 1% when Si PV manufacturers use less GHG-intensive sources of electricity. Based on these findings, we recommend strategies for PV manufactures to most effectively decarbonize their supply chain even if they are in geographies which rely on high-carbon electricity. Additionally, we identify important gaps in the lifecycle inventory (LCI) over the PV supply chain which need to be addressed. The increased data transparency will enable lifecycle assessment (LCA) practitioners to more robustly quantify the climate benefit of different PV material and design choices and the difference in climate benefit from PV modules meeting the benchmarks defined in the ultra-low carbon PV standards.