This data-file is our LONGi technology review, based on recent patent filings. The work helps us to de-risk increasingly efficient solar modules, a growing focus on perovskite-tandem cells, and low-cost solar modules, with simple manufacturing techniques that may ultimately displace bottlenecked silver from electrical contacts. Key conclusions within.
LONGi is the largest solar module producer in the world, on a trailing 5-year basis, producing 60GW of PV modules in 2023, founded in 2000, headquartered in Xi’an with shares publicly listed in Shanghai. The company features in our screen of solar module manufacturers.
LONGi aims to continue driving efficiency gains through the solar industry, especially via HJT cells and perovskite tandem cells. In November-2023, LONGi set a new world record of 33.9% cell-level efficiency for a silicon-perovskite tandem cell, which is the first ever cell to surpass the Shockley-Queisser (S-Q) theoretical efficiency limit.
Hence in this LONGi technology review, we have evaluated twenty recent patent families, mainly those filed from 2022 and 2023. Our conclusions, and key learnings from this exercise, are in the data-file.
Manufacturing details were the highlight. One patent covers the nineteen step process from silicon wafer to finished cell, step by step. What surprised us is the high reliance on simple processes (e.g., polymer adhesive tapes, lasering, vapor deposition) and away from more complex semiconductor manufacturing techniques.
Increasing efficiency was the underlying focus in 80% of LONGi’s patents (chart below). Increasing efficiency historically explains 40% of solar cost deflation and is very likely set to continue.
The breadth of options being explored strongly suggests that solar module efficiency will continue improving by at least 0.5%+ per year (absolute terms), and likely higher as perovskite/tandem cells reach commerciality (details in the data-file).
Silver bottlenecks in the solar industry have been a major feature in our recent research, and across our work into silver. 30% of the patents in our sample focused on ways to displace silver out of PV modules. Updated conclusions on silver are in the data-file.
Key challenges for perovskite/tandem solar cells are also described in LONGi’s patents, and summarized in our LONGi technology review. But how much can we de-risk the solutions intended to overcome these challenges, and how much running room lies ahead?