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7 September 2022

China catching up on CdTe and other niche photovoltaics

Chinese manufacturer Advanced Solar Power has reached a module efficiency rating of 17.19% on a Cadmium Telluride (CdTe) module, not far behind the 18.7% claimed by the CdTe industry leader, US-based First Solar.

China’s technological gap has narrowed to almost nothing for mainstream silicon photovoltaics. But until now, the niche semiconductor technologies of Copper-Indium Gallium Selenide (CIGS) and CdTe have remained dominated by Western players, even as they shrank to a few percentage points of the total market. Chinese companies have been pursuing these alternatives too, but without the scale that enabled the national industry to catch up as swiftly as with Si-based photovoltaics.

Advanced Solar’s first production line was brought online in 2011, sent its first module for commercial tests three years later, and spent some further time producing panels without yet selling them. In this period the company had to place a high emphasis on quality research. Any hint of excessive degradation of its modules would hurt its reputation and sales. Measured at the cell level Advanced Solar Power weighs in at 20.61% – compare again to First Solar’s rating, which for cells has reached 22.01% – with an aspiration towards 24%.

The appeal of these technologies is their low weight. This makes them suitable for Building Integrated Photovoltaic (BIPV) installations – solar modules which are thin, light and sturdy enough to double as floor tiles and exterior wall surfaces. According to Zheshang Securities, the global BIPV market will roughly double every year from now until 2025, at which point it will weigh in at $18 billion. While we expect utility-scale solar to stage a comeback as module prices decline for the rest of this decade, in the long term through to 2050 distributed photovoltaics are the future.

Right now, distributed solar is being massively boosted by Europe’s energy woes and China’s municipally-administrated rooftop solar incentive schemes. Even crowded metropolises such as Shanghai are pursuing photovoltaic installations – Advanced Solar says it can install 4.2 kW on a 30 meter square skylight, and that it is looking into a photovoltaic sunroof offering for EVs.

Besides China’s own BIPV demand, non-silicon technologies such as CdTe will become more competitive for export to the West if more countries use carbon emissions as a metric by which to tariff Chinese modules, as South Korea already does – silicon photovoltaics rely on coal-generated electricity to purify their polysilicon, while other technologies are not so energy-intensive.

Another alternative photovoltaic semiconductor, perovskites, also saw progress of late in China, with the very first delivery of perovskites having occurred back in July – with 5,000 pilot modules installed at commercial and industrial sites across Zhejiang Province, courtesy of start-up Microquanta. So, China is only one year behind the West, which saw Saule Tech make its first delivery of perovskite solar in August 2021.

In related news, the 2022 HJT & Tandem Photovoltaic Technology Summit was held in Shanghai on September 2nd. At the event, Huasun New Energy presented itself as holding a strong position in heterojunction (HJT), a type of silicon photovoltaic being invested in across the industry. According to Huasun and other sources, 120-micrometer wafer thickness and 100 milligram silver paste usage per cell will both be achieved by the end of this year, which will overturn HJT’s cost disadvantage compared to Mono PERC.

From that point, Huasun wants to be the first to reach a heterojunction-perovskite tandem, saying it targets 30% module efficiency by 2025, with a single solar panel weighing in at 840 Watts or more. In January of this year perovskite investment in China had already been tracked at over $1 billion, with multiple 100-MW pilot lines – though the distance to commercialization remains indeterminate and these pilot lines are in the hands of start-ups, not the industry giants.