Why is HJT getting so popular among manufacturers and suppliers?

Undoubtedly, heterojunction (HJT) solar panels are highly promising. This technology is quite sophisticated and can attain more than 23% efficiency in solar cells. It’s adequate for application on both sides and performs well across various temperatures.  HJT requires fewer processing steps than other efficient techniques and is four steps shorter than PERC. It employs low-temperature operation, making thinner and more compact wafers practical.

Cell producers should select HJT technology, considering performance and production aspects. However, several businesses have hesitated to utilize HJT technology, making the wait for its broader adoption feel prolonged for the suppliers providing essential equipment for critical manufacturing processes.

A brief flashback about HJT?

The technology known as Heterojunction with intrinsic thin-layer cells, abbreviated as HIT, was initially introduced by the Japanese company Sanyo two decades ago. Their research on solar cells began in the 1970s. In 2011, Panasonic acquired Sanyo and continued to focus on the HIT projects. The technology is referred to as HIT by the Japanese company, which holds its trademark. The cell structure features the addition of a pair of very thin amorphous silicon (a-Si) layers to either side of a crystalline silicon (c-Si) wafer. One consists of a pristine layer and a second layer modified to enhance its properties. The initial layer of pure a-Si plays a crucial role in safeguarding the c-Si layer, ensuring its optimal functionality. The additional layers form the structure of the p-n device. A transparent conductive oxide (TCO), commonly indium tin oxide, is deposited over the a-Si layer.

Over about 13 years, Sanyo and later Panasonic manufactured HIT cells and modules with energy efficiency, protected through patents. Throughout that period, there has been a significant increase in efficiency. In 1997, the production of HIT cells achieved an efficiency rate of 16.4%. That number went up to 19. 3% in 2007 and is now 22—2%. In early 2017, Panasonic revealed that it had produced 18 million HIT solar panels in the previous two decades. As of now, they have extended their warranty in Europe to 25 years. It shows that the temperature affects the performance by -0. 258% for every degree Celsius, indicating that it performs more effectively in hotter climates than standard solar panels.

The new marketplace for HJT

In 2010, the intellectual property rights for Panasonic’s HIT technology ended. This enabled additional companies to adopt the technology and introduce new products to the marketplace. The patent’s expiration sparked significant enthusiasm and engagement among manufacturers of solar panel equipment and technology providers in related industries, such as semiconductor and flat panel production. This was remarkably accurate for crucial stages in the HJT process, such as PECVD, PVD, and wet chemistry. Yet, the number of significant HJT manufacturing endeavors has appeared to be more like a slow drip than a swift influx. 

According to independent solar specialist Corrine Lin, there’s a lack of significant interest in how Chinese cell manufacturers implement HJT technology. She states that only a few prominent Chinese solar cell manufacturers are working with HJT. A key example is Jinergy, which announced in April that it began producing a significant quantity of its double-sided HJT panels.  Jinergy announced that it is achieving cell efficiencies of 23% along with a temperature coefficient of -0.28% per degree Celsius.

The turning point in the HJT manufacturing and supply

Numerous technology firms believe that if a significant Chinese solar cell manufacturer begins utilizing HJT technology, it will probably encourage other companies to follow suit. The timeline remains uncertain, posing a substantial question within the solar industry: When will this occur?

Frank Jürgens, the sales and marketing director at Indeotec, a Swiss firm specializing in PECVD systems, remarked that industry adoption of HJT technology would begin once early testing reveals efficiency rates exceeding 23% for all clients. He states that this should be demonstrated on production lines capable of generating a minimum of 100 MW, utilizing specific tools to manage this output level. “However, Omid Shojaei, the CEO of Investec, emphasizes that our focus extends beyond merely the pilot phase.” s

Indeotec, founded in 2011,  has supplied five Octopus II PECVD/PVD systems to research facilities worldwide. The technology startup is based in Oerlikon and specializes in manufacturing a-Si equipment. They believe their “mirror” deposition technology prevents blending pure and modified a-Si layers. This edge enhances their effectiveness compared to existing solutions. Indeotec’s ‘mirror’ PECVD reactor technology enables coating both faces of a silicon wafer without the need to flip it or expose it to air. When integrating the TCO layer, Von Ardenne can perform a comparable action.

Asian technology equipment vendors are advancing HJT technology. At the same time, Taiwan’s Archers has a record of providing equipment to NSP, another Taiwanese company, as it pivots to manufacture high-efficiency solar cells. China’s Ideal Energy Equipment has partnered with Von Ardenne to collaborate. Ideal Energy revealed in July that they secured new equipment orders to facilitate mass production on an HJT line, but additional specifics are still pending.

The collaborations between equipment suppliers and their initiatives to enhance HJT technology demonstrate significant promise for reducing production costs. Singulus said the Hevel HJT project utilized ozone for wafer processing, resulting in substantial cost reductions. The Singulus team clarifies that producing HJT is more akin to semiconductor fabrication than solar panel manufacturing. They believe that practices from the expansive semiconductor field can be implemented, likely leading to considerable cost efficiencies.