Coming up as a worthy successor to the current solar PV workhorse Passivated Emitter and Rear Contact (PERC), the Tunnel Oxide Passivated Contact (TOPCon) is carving its own place in the world of solar PV technology. While higher efficiency than PERC is definitely its highlight, manufacturers cite lower costs and greater durability as other benefits.
To discuss the various facets of this solar cell technology, on October 16, 2023, TaiyangNews organized a Special Focus Webinar on TOPCon, The New State of the Art; The Versatile Technology Platform Serving Different Applications. We had speakers from leading Chinese solar PV manufacturer JA Solar discussing the latest advances in TOPCon technology, its potential for various applications along with reliability aspects from TÜV SÜD.
Presenting the company's next generation n-type TOPCon DeepBlue 4.0 Pro series, Senior Technical Sales Engineer at JA Solar, Francesco Liuzza, said the core technology that differentiates its TOPCon modules from the others is its SMBB technology with 16 busbars (BB) that improves the use of light, and high-density encapsulation technology to avoid micro-crack issues at cell interconnection.
Based on the new-generation rectangular silicon wafer, Liuzza said these kind of silicon wafers can meet requirements of different products and applications as floating solar, hybrid solar, rooftop solar and the like. It can reach the highest power output of 630 W and highest efficiency of up to 22.5%, with a cell efficiency of 25.6%.
Compared to the original n-type module, Liuzza said the DeepBlue 4.0 Pro offers 1.4% to 2.8% lower BOS and 0.7% to 1.6% lower LCOE.
As it works on improving efficiencies for TOPCon as well as heterojunction (HJT) along with progress in the encapsulation technology, the Chinese manufacturer plans to bring out monofacial n-type products in H1/2024. All of these will use rectangular wafer and half-cut cells.
Having started as a cell producer, the company has today expanded vertically to ingots, wafers, and modules as well. JA Solar's Director Sales, DACH, Spain and Portugal PV Power Plants, Wolfgang Löhnert shared that it is now aiming for 85 GW annual production capacity for ingots, wafers and cells each by the end of 2023, while module capacity is targeted to grow to 95 GW. The module expansion plans include the 2 GW fab in Arizona, US (see JA Solar Takes US Solar Module Manufacturing Steps).
According to Liuzza, the share of its DeepBlue 4.0 series of TOPCon modules in the overall module production capacity of the company at the end of 2023 will be 60%, and grow to account for 70% of all module capacity by 2024-end.
With such a significant presence in the vertical integration of the solar PV supply chain, Löhnert believes it is easy for the company to have a strict control over the quality and reliability of PV products being sent into the market. In fact, it uses this argument as its strength to stay ahead in the market.
Yet it remains dependent on external suppliers for raw material and other components which is where the focus on reliability and quality needs to increase. With sustainability on mind, Löhnert said the company is actively addressing climate change concerns by ensuring green raw material supplies from vendors, green packaging and low carbon logistics in its supply chain. Recycling of its solar modules at the end of their working life is also on the agenda for the manufacturer, stated Löhnert.
Like JA Solar, sustainability is now the buzzword for solar PV manufacturers across the spectrum, according to the Senior Technical Expert of TÜV SÜD Certification and Testing (China) Co., Ltd. Yunzhe Yan.
Listing the key technical points of PV module reliability tests and eco-design, Yan stated reliability as the basis and prerequisite of safety and eco-design of modules. These can be designed according to existing standards of the IEC. Currently, the most standard tests used in the industry are the basic ones including IEC 61215/61730, and those related to PID, LETID, salt, sand, snow, UV radiation, among others.
The standards, explained Yan, that haven't been used widely so far but need to be are related to PID delamination, high temperature and temperature change, since modules face a high risk from material failure, hot spot and fire risk. These can critically impact the reliability and performance of modules, along with the environment.
While reliability is about quality, eco-design is related to sustainability. As the term suggests, eco-design considers the impact of modules on the environment at the product design phase itself. Yan said approximately 80% of all product-related environmental impacts can be addressed at the design stage of modules, interest in which has been increasing of late, especially in Europe.
One of the biggest markets for solar PV modules, Europe has been making efforts in environmentally sustainable module products since the 1960s. The European Union (EU) already has the Ecodesign Directive for energy-using products launched in 2005, and amended in 2009.
As more such directives come into force, manufacturers will be forced to rethink their product design with an eye on sustainability, she added.
Executive Panel
During the panel discussion moderated by TaiyangNews Head of Technology Shravan Chunduri, the speakers deliberated on the status quo of TOPCon with a focus on technology, availability and quality.
JA Solar's Francesco Liuzza said even though TOPCon is proliferating, the company still produces p-type modules to cater to the demand. His colleague Wolfgang Löhnert explained that switching over entirely from p-type to n-type is a cost-intensive process. Also, in the short-term future, TOPCon is to lead the industry but its time will be short-lived as newer technologies such as HJT, IBC and tandem become more mature. Hence, JA's strategy is to not switch over to TOPCon completely at present.
The company's cell efficiency roadmap, as shared by Liuzza, shows the manufacturer is working on n-type HJT, XBC and perovskite-silicon tandem cells, aiming to achieve 26.5%, 27% and 29% efficiency by 2025, respectively.
TÜV SÜD's Yunzhe Yan once again stressed that while regulations for eco-design help, it is seeing growing interest from manufacturers for the same as they believe it not only improves the product reliability but also fulfills their responsibility towards the environment.
Answering Chunduri's query about the cost impacts of going sustainable, Löhnert admitted to the cost implications, but emphatically added that it will all eventually pay off at the end—both for the renewable energy source that solar PV represents as well as for Planet Earth—it will be worth it.
TaiyangNews will take forward the discussion on reliability on October 26, 2023 during our Reliable PV Module Design Conference—How to Ensure a Solar Panel's High Performance for Decades. Register free for the event here.