Why Bifaciality Matters For Back Contact Technology

TaiyangNews: You are the co-chairman of the 12th edition of the world-famous bifiPV Workshop, currently taking place at AIKO Solar’s headquarters in Zhuhai, China. What drives AIKO to host this global technology gathering?

Christian Peter: AIKO’s DNA is innovation. Until 2021, we were a pure PERC solar cell manufacturer and were known in the PV community only by experts. We then started developing our ABC back contact cell technology which we introduced to the market last year. We want to increase awareness amongst people about R&D, which is key to bringing solar to the next level. This event is also about cooperation between research institutes and the industry – and AIKO has been unique here as we are not only cooperating with institutes but we are the only ones to have established a research facility on our own abroad, in Europe.

We want to discuss the latest scientific results and case studies. As you know, utilities, for instance, are very interested in the bifaciality factor of cell technologies as there are quite a few differences. However, the question here is what this means in terms of the energy harvest, and LCOEs in the end. While back contact technology’s bifaciality factor is somewhat lower than TOPCon, this highest-efficiency technology is the superior solution for many scenarios in the rooftop and utility segments. Workshop participants also have the opportunity to see our fully operating main production line in China, which is another highlight.

TaiyangNews: AIKO is well known among installers and investors for its world-record efficiency back-contact solar cells. While BC technology has indeed been famous for record efficiencies, it hasn’t for its bifacial capabilities. What are we missing?

Christian Peter: You are right. Look at the TaiyangNews TOP SOLAR MODULES listing, where we have been ranked 1st for the last 19 consecutive months – just with front-side efficiency. On the other hand, back contact does not reach the level of bifaciality as heterojunction or TOPCon products. But what does it mean? The bifaciality factor of BC technology is a bit over 70%, while the world record for heterojunction is around 90% and TOPCon about 85%. But the key question to be answered is - what does it mean in terms of LCOE and energy harvest? And that is something we want to discuss.

In the standard scenario, you can have about 7% light coming from the backside, which you have to multiply with the difference of the bifaciality factor. The best efficiency of our commercial BC modules in the TaiyangNews ranking is 24.2%, and this is only from the front side. In the same ranking, the best heterojunction efficiency is around 23.2% and 23.0% for TOPCon. If you put this all together, you can see that even with a lower bifaciality factor, ABC still delivers the best energy yield, and this is something that escapes people’s eyes.

TaiyangNews: You are heading AIKO’s European solar technology lab in Germany. How much of your research has been going into bifacial technology, even if it has a rather low impact as you already mentioned?

Christian Peter: Bifaciality is not our main research task; we focus on cost and efficiency where we are the leader. But the utility-scale market is asking for bifacial modules, so we do have a team taking care of this. It’s about optimizing the back contacts. In the overall equation, we are quite competitive with 70%. This is what we want to show through case studies, which is a bigger research topic at the moment. We are also conducting case studies with different institutes in different climate zones from South America to Australia or China to Europe to gather data from markets with different installation scenarios. This will help us show our customers and the market that BC is the best technology in any case.

TaiyangNews: How does this whole bifacial topic fit into your business strategy now, and particularly regarding utility-scale, a segment you are now expanding into?

Christian Peter: The utility-scale market is a totally price-driven market, and the product at the end is not the solar module, but it’s electricity. While the great aesthetics of our products can help us win some projects in the residential segment, it’s not the case with utility-scale. What matters to developers of such projects is LCOE. It's a financing question, so money matters here more than everything – and that’s why bifaciality is an important factor. Our bifaciality factor of 70% has a positive impact on LCOE, adding to our leading front-side efficiency, and we couldn’t succeed in utility-scale without that. Our calculations show that you can get an energy delta of 1%. And in a market where every cent matters, this delta becomes very important. A better LCOE of AIKO modules convinced our first utility-customer in Europe, who chose us also for the second phase of project in Bosnia-Herzegovina, after our products generated 12% more power and reduced electricity costs by 3% than other brand modules used.

TaiyangNews: Thank you for the interview.

TaiyangNews is media partner of the bifiPV Zhuhai 2024 conference and responsible for moderating the executive panel with CTOs/CSOs from Aiko, Longi and Maxeon. For the conference agenda check here.