How will manufacturing capacity additions in China and North America affect the carbon footprint of silicon photovoltaics?

Global annual PV installation is expected to increase from 150 GW in 2021 to 820 GW in 2030 to reach net zero emissions by 2050. Electricity production from PV generates almost zero carbon emissions, but the emissions from the manufacturing phase are nonnegligible. While most installed PV modules in the US are imported from China, manufacturers are expanding the manufacturing capacity in North America to reduce reliance on Chinese PV modules. Although it has been commonly perceived that the North American modules would have a lower environmental footprint than Chinese ones, the effect of capacity expansions and regional impact considering where each component is produced has yet to be fully understood. This study aims to compare the carbon footprint and cumulative energy demand of PERC modules manufactured in China and North America based on the expected 2024 manufacturing capacity additions. We develop PV manufacturing scenarios to perform life cycle assessment (LCA) for the first time considering the regional manufacturing capacity, partnerships between suppliers and manufacturers, and regional electricity grids, while previous PV LCA studies evaluated the national average production. The carbon footprint of China's PERC modules for monofacial and bifacial designs, when using the national average grid, is 517 and 412 kg CO2eq/kWp, respectively. In comparison, the GWP of modules produced in North America is 22.0–22.2 % lower than in China, a difference attributed to the lower carbon footprint of electricity grids. When considering where each component is made, the GWP increases by 1.5 % in China compared to the national average. This difference arises because most of China's solar manufacturing facilities are in regions with higher carbon intensity grids than the national average. Solar manufacturers can reduce the carbon footprint of their products by changing manufacturing locations or increasing the share of renewable sources for manufacturing. We find that both China- and North America-made PERC modules meet the Electronic Product Environmental Assessment Tool (EPEAT) low carbon solar criteria (630 kg CO2eq/kWp). However, to meet the ultra-low carbon solar criteria (400 kg CO2eq/kWp), a significant share, approximately 60 % for China and 15 % for North America, of the total electricity supply must be sourced from renewable energy in addition to the existing grid. This study identifies the significant impact of manufacturing locations on the overall carbon footprint of PV modules. It is important to consider production locations by stage and the regional electricity supply when developing the carbon assessment methodology of PV modules. Otherwise, manufacturers may take advantage of assessing carbon footprint using the country's average grid while producing products in dirty grid regions.