Day 4 of the High-Efficiency Solar Technologies 2025 Conference focused on heterojunction (HJT) technology. The panel discussion was moderated by TaiyangNews Head of Technology Shravan Chunduri, with panelists Kaining Ding, Head of the PV-ThynC Lab at Forschungszentrum Jülich, and Huasun Energy’s Head of Business Development Europe, Christian Comes.
Here’s an edited summary of the panel discussion.
TaiyangNews: HJT seems to be at a crossroads. From both a technology and market perspective, how would you define HJT’s position today? Is it a niche technology, a premium option, or a technology in transition?
Christian Comes (Huasun Energy): In terms of market share, HJT is still a niche because production volumes are small compared to other technologies. But from a product perspective, it is very competitive.
This mismatch exists because the market has been behaving in an unusual and illogical way for several years. As an engineer, I believe market logic will eventually return. When that happens, HJT will be a strong competitor to TOPCon, as its fundamentals are solid.
Kaining Ding (Forschungszentrum Jülich): I fully agree. The market today is not normal, so it is hard to make logical conclusions. If we assume a return to a healthier market where companies can earn money again, we will likely see 3 main technologies – BC, TOPCon, and HJT – with similar costs and efficiencies.
All 3 are approaching the theoretical efficiency limit of crystalline silicon. Moving beyond that will require tandem technologies, but perovskite is not yet mature enough for large-scale deployment.
This means no technology has a clear advantage right now. Some niches may emerge, and technologies may even merge. A single breakthrough could change everything, whether for HJT, BC, or TOPCon. Because of this uncertainty, it is very difficult to predict the future.
TaiyangNews: HJT no longer shows a clear efficiency advantage in module rankings. Are there still performance factors that could improve its relevance, even though many options – like thinner wafers and advanced layers – have already been used?
Christian Comes (Huasun Energy): Some improvements are not yet public, while others will be implemented in the next 2 years. For example, Risen Energy has shown that the next generation of HJT could have a 2-cent cost advantage, which is significant.
This is partly because HJT uses less material and is less sensitive to rising silver and silicon prices. High bifaciality is another key advantage, especially for vertical installations, where HJT is often the best option.
One major weakness today is high capital expenditure. Many tools come from the semiconductor industry and are expensive. If new equipment solutions – such as advanced wire technologies – reduce CapEx, it could be a game changer.
Kaining Ding (Forschungszentrum Jülich): Comparing PV technologies today is like choosing stocks – market dynamics play a big role. Decisions are driven by people, roadmaps, and momentum.
At the moment, there is no big enough efficiency or cost gap to clearly favor one technology. This can change if a breakthrough improves efficiency or lowers cost. Efficiency remains the top priority, followed by cost. Other benefits, such as bifaciality, come after that.
TaiyangNews: There are different views on the cost gap between TOPCon and HJT – 0.5 cent, 1 cent, or even 2 cents. What is the realistic situation today?
Christian Comes (Huasun Energy): If we compare our selling prices, where we are not making losses, with market prices where many TOPCon players report losses of around 10%, then I would say there is no real cost difference today. But this assessment has some uncertainty.
TaiyangNews: HJT uses less silver and is a low-temperature process, but it uses indium and requires higher CapEx. What are the main cost drivers compared to TOPCon?
Christian Comes (Huasun Energy): Indium is not a major concern. CapEx is the main cost driver. HJT can tolerate higher oxygen and metal impurities in polysilicon because gettering works well at low temperatures. This allows us to use 100% FBR polysilicon, which is cheaper and has a lower carbon footprint.
TOPCon requires higher-purity silicon and tighter impurity control, which limits the use of FBR. In the medium to long term, these material advantages should give HJT a cost benefit.
TaiyangNews: Silver prices are rising. Since HJT uses less silver, could this become a competitive advantage?
Christian Comes (Huasun Energy): Yes and no. Copper electrodes work well with HJT because the TCO layer prevents copper diffusion. We have tested full copper electrodes, but today, silver paste is still more cost-effective when implementation costs are included.
If silver prices rise significantly, switching to copper would be easy from a technical standpoint – it would mainly be a management decision.
TaiyangNews: Most new HJT startups are outside China. Why is that, and how do you see their future?
Christian Comes (Huasun Energy): The main reason is the US market. TOPCon faces patent issues there, while mono-PERC and HJT do not. Mono-PERC is proven and simple, but HJT also makes sense due to strong performance and no patent risks.
This is why we see more manufacturing outside China to comply with trade restrictions while offering reliable, patent-free products.
TaiyangNews: What about your European joint venture in Italy?
Christian Comes (Huasun Energy): We have signed agreements and plan to establish manufacturing capacity in Italy. The goal is to supply Europe and transfer technology locally.
Reshoring production is technically easier than many think. The challenge is market overcapacity and price pressure. Still, there is a market segment for this, and we plan to serve it.
Kaining Ding (Forschungszentrum Jülich): China can supply the world with low-cost modules. Local manufacturing elsewhere only makes sense because of political frameworks like tariffs or incentives. These do not automatically favor HJT, except in specific cases like IP restrictions.
TaiyangNews: Looking ahead, will HJT grow as a standalone technology, evolve into BC, or mainly succeed as part of the perovskite tandem?
Christian Comes (Huasun Energy): If tandem does not work, we will see more back-contact HJT. However, both back-contact and tandem have lower bifaciality, so for applications like vertical installations, HJT will still be preferred.
Kaining Ding (Forschungszentrum Jülich): I like the hybrid HIBC concept. Pure HBC with HJT on both sides is challenging for mass production, but hybrid solutions solve key issues.
TaiyangNews: To close, what one or two decisive steps could put HJT on a strong growth path in the next 3 years?
Kaining Ding (Forschungszentrum Jülich): Ignore the noise and keep working. Progress will come.
Christian Comes (Huasun Energy): First, introducing CO₂ restrictions in PV value chains would favor HJT. Second, restoring normal market conditions – where companies cannot operate at losses indefinitely – would allow HJT's lower LCOE and proven reliability to stand out naturally.
TaiyangNews: Thank you.
Conference summaries for all 4 days are available here.