Nankai University model: silver from China's retired PV modules peaks at 739 t/yr in 2044

Researchers led by Nankai University in Tianjin modelled silver flows in photovoltaic modules installed in China in 2000–2025 and projected them to 2060, according to a study in Sustainability. Under the baseline lifetime scenario, silver from retired modules peaks at 739.34 t per year in 2044, nine years before retired capacity peaks in 2053 mdpi.comSustainabilitymdpi.comOpen source ↗. Retired capacity at that peak is 70.77 GW. The authors describe the model as a cohort-based dynamic material flow analysis.

Silver intensity and in-use stock

Pure-silver intensity was reconstructed from cell dimensions and efficiency, paste consumption, metallization composition and technology shares. Technology-weighted intensity fell by 62.0% from 2018 to 2025, from 23.33 to 8.86 mg/W. Over the same period, annual silver inflow with new installations rose by 170.4%, from 1,149.66 to 3,108.88 t. At the end of 2025 the in-use stock was 17,784.12 t, equal to 99.5% of cumulative installation inflow.

The peaks do not coincide because early cohorts were smaller but carried more silver per watt. Early-generation crystalline silicon modules account for 88.4% of retired silver in 2025. At the 2044 peak their share falls to 48.6%, with PERC modules at 31.1% and TOPCon at 16.6%. By 2060, PERC and TOPCon together make up 91%.

Lifetime and recovery scenarios

Weibull lifetime distributions were used to compare four module-lifetime scenarios. Module lifetime mainly determines release timing, while silver intensity affects the magnitude mdpi.comSustainabilitymdpi.comOpen source ↗. Across the scenarios the peak falls between 2042 and 2052, at 566 to 1,425 t per year. In Monte Carlo runs of the baseline, 80% put the peak between 2039 and 2048.

Four recovery-rate pathways were also compared. Cumulative potentially recoverable silver in 2025–2060 ranges from 3,606.94 to 15,335.65 t. A constant 21% rate gives about 3,607 t. Linear growth to 90% gives 15,336 t if reached by 2030, 13,682 t by 2045 and 10,612 t by 2060. The authors state that these are scenario-based aggregate multipliers, leave out collection, pretreatment and refining losses, and do not represent actual secondary-silver production.

The model covers only modules installed in China through 2025, so silver in future installations is not included, and imports, exports and inventory changes are not modelled. The authors say recycling facilities should be planned around the technology mix and silver intensity of retiring cohorts, not only retired capacity.