Perovskite cells are the next generation of solar energy tech, and China is leading their development

On Monday, we reported that CATL 宁德时代, China’s biggest battery maker, announced that it had registered a patent for a perovskite solar cell. This is a next-generation solar panel material, not yet commercially available, that promises to be easier to manufacture and cheaper than silicon. CATL’s patent includes the cell’s manufacturing method and related electrical equipment.

In fact, China’s perovskite solar cell industry is already quite advanced. This week, an all-perovskite tandem battery module (i.e., solar cells that can be either individual cells or connected in a series) developed by Renshine Solar 仁烁光能 was certified by the Japan Electrical Safety and Environment Technology Laboratories (JET) as attaining a conversion efficiency rate of 24.5%, in other words, the module can convert 24.5% of the solar energy shining on it into usable electricity.

This percentage is highly significant, because the highest certified conversion rate so far of conventional modules that use monocrystalline silicon is 24.24%. Those modules were developed by the Chinese company Trina Solar 天合光能, which, per an announcement earlier this month, has just developed modules that achieved a conversion efficiency rate of 26.1%, as certified by the China National Institute of Metrology.

Perovskite solar cells might be able to do even better: The theoretical limit of the conversion efficiency rate of crystalline silicon solar cells is only 29.3%, whereas, in theory, single-layer perovskite cells could reach a conversion efficiency rate of up to 33%. Double-layer perovskite stacks could reach up to 45%, and all-perovskite triple-layer stacks could reach up to 50%.

There is another huge advantage of perovskite: While the production of crystalline silicon requires at least four factories and up to three days, with high energy consumption, perovskite cells can be produced in one factory in 45 minutes at much reduced cost.

The rising stars of perovskite

Renshine Solar, which was established in 2021, is one of the leading Chinese companies pushing the commercialization of perovskite solar cells. Earlier this year, the company signed an agreement with an industrial zone in Changshu, Jiangsu Province, for the construction of a 150 megawatt (MW) perovskite module production line, set to be completed in the third quarter of 2023. In August, Renshine Solar announced the completion of a Pre-A round of financing of hundreds of millions of yuan, which will be used to construct the new production line in Jiangsu.

UtmoLight 极电光能, which completed Pre-A round of financing of 220 million yuan ($30.11 million) in October 2021, has researched perovskite technology from 2018, and has (like Renshine Solar) developed successive perovskite cells with steadily increasing conversion efficiency rates. UtmoLight is also currently constructing a 150 MW perovskite module trial production line, which will be put into operation in the fourth quarter of this year. The line will produce specialized solar energy products for buildings, namely photovoltaic curtain walls, facade power generation materials, and photovoltaic roof tiles. In August this year, UtmoLight signed an agreement with an industrial zone in Wuxi, Jiangsu Province, and will invest 3 billion yuan ($410.68 million) to develop the world’s first gigawatt-level perovskite photovoltaic production line. UtmoLight is currently undertaking a new round of financing that will support the costs of the new production line, and construction on the project will commence in early 2023.

The government is also providing policy support: In August this year, the Ministry of Science and Technology and eight other government departments issued a carbon peaking plan for 2022-2030 that specifically mentions perovskite cells.

Early days

In 1839, German mineralogist Gustav Rose picked up a rock on the slopes of the Ural mountains, and named it perovskite after his Russian peer Lev Perovski. Perovskite is a crystal structure that mainly consists of carbon, hydrogen, nitrogen, lead, and iodine, and is widely distributed on earth, and is very cheap. When exposed to sunlight, perovskite acquires the ability to easily absorb and release electrons. In 2009, a Japanese scientist created the world’s first perovskite solar cell, which had a conversion efficiency rate of only 3.8%.

Perovskite cells now have a wide range of industrial applications, including photovoltaic power stations, building-integrated photovoltaics (BIPV), solar roofs for new energy vehicles, and charging accessories for consumer products. Perovskite batteries are also a possibility in the future, but there are as yet no commercial battery products.

According to UtmoLight founder Yú Zhènruì 于振瑞, 2022 is the first year of perovskite industrialization, and China is leading the commercialization of perovskite solar cells. Yet he acknowledges that the technology is still in its early stage. There are also lingering doubts in the industry whether perovskite cells can last beyond 25 years: Further testing is still required to verify the durability of the technology. There are other teething problems with perovskite industrialization:

• Perovskite cells still have high lead content, and the toxicity could be a concern if perovskite cells are produced in large quantities. (This problem might be relatively easy to solve as the lead can be replaced with other elements.)
• Perovskite cells are not yet adequately stable, and are easily affected by temperature and humidity, and their efficiency decays rapidly in outdoor environments. According to one industry estimate, the current level of stability of perovskite cells is about ten years, but this period is increasing rapidly as the technology matures.
• Mass production of perovskite solar cells is now the key challenge, as the current exploratory production lines will need to make rapid progress towards an integrated supply chain and a commercialization process.

The takeaway

Although it is still early days for perovskite industrialization and commercialization, the technology might well be the future of the photovoltaic industry.

China is already the leader of the global silicon photovoltaic industry, and looks set to dominate the perovskite solar industry too: Chinese entities currently hold a total of 2,282 or 68% of all perovskite battery patents, far more than the around 300 patents held in total by the U.S., Japan, and South Korea.