The International Energy Agency's Photovoltaic Power Systems Programme has published a comprehensive update to its life cycle inventories, the reference database of materials, energy use, emissions and processes across the manufacture, operation and recycling of PV systems. The previous edition dates from 2020, and the gap matters: almost every assessment of solar's environmental performance in the intervening years rested on inventories describing a supply chain that no longer exists.
A data basis rebuilt from the factory floor
"The most important improvement in the 2026 report is the data basis for the monocrystalline silicon supply chain. It draws on 83 factory-level LCAs collected in the context of the French PV tender process operated by ADEME between 2022 and 2025," said Matthias Stucki of IEA-PVPS Task 12, a contributing author of Report IEA-PVPS T12-33:2026. Compared with previously available public datasets, he said, this substantially increases representativeness, so the inventories now reflect the technologies actually dominating the market, including TOPCon on n-type wafers and current wafer and module designs.
Coverage is quantified. The monocrystalline silicon dataset for TOPCon cell technology represents approximately 29% of global polysilicon, 16% of global wafer, 7% of global cell and 9% of global module production capacity. Cadmium telluride data represent more than 90% of the CdTe module market. The update also adds new country-specific PV mix figures and a new category of bottom-up simulated inventories for advanced monocrystalline silicon manufacturing, developed at Fraunhofer ISE, which model the chain from polysilicon to module with explicit mass and energy balances including factory buildings, facility infrastructure, water management and waste treatment.
Where the impact reductions come from
"What stands out most is how much the silicon supply chain has changed since the previous report, and how directly this shows up in the inventory," Stucki told pv magazine. The aggregated industry data show a clear increase in the share of internally recycled silicon in ingot production. This is a specific, well-defined loop: scrap from the cropping and squaring of monocrystalline ingots retains solar-grade purity and can be reintroduced into crystal growth, and in the inventories the closed loop is modelled as a dedicated process with its own material and energy inputs.
Sawing has improved too. According to pv magazine's report on the updated PV life cycle inventory, ever thinner diamond wires have further reduced kerf loss, so less silicon is lost per wafer in the first place. Taken together with thinner wafers and improved process efficiencies, Stucki said, the environmental impact of the module supply chain has decreased markedly, and the same is true for inverters.
The exergy view
Polysilicon is one of the most exergy-intensive materials in the energy sector: reducing and purifying silicon to solar grade concentrates an enormous quantity of work into a few grams per wafer. Two of the reported changes attack that directly. Closed-loop ingot scrap recycling retains the purity already paid for, avoiding the full exergy cost of re-purification — the cheapest possible upgrade, because it skips a separation entirely. Thinner diamond wire reduces kerf loss, which is destroyed exergy in the most literal sense: high-grade silicon converted into slurry. Measuring these gains in an inventory grounded in 83 real factories, rather than in generic averages, is what makes a credible cumulative exergy demand figure for a module possible.
