From Throughput To Advanced Process Optimization

Historically, the primary evaluation point for production equipment has been throughput, followed by mechanical yield and material consumption. These are no longer the key points of optimization for major equipment vendors. The majority of production equipment platforms achieve very high throughput. Today, there are single tools available for certain processes with production capacities exceeding GW-scale. It would be no exaggeration to say that this segment has evolved far beyond its fundamental requirements.

We can also see this reflected in the current survey on Solar Cell Production Equipment 2025. Starting with the wet-chemical benches used for surface preparation, throughputs have increased by 15% to 25% over the levels described in our previous survey in 2023. Among the most notable developments in the wet-chemical systems is the focus on the management of water and waste, which have become an essential feature for 2 companies – RENA and SCHMID. The former even presented a roadmap to reduce water usage by 70% in the coming years.

Moving to the core of the process, a pyramid size of about 1 μm was characterized as optimum in our previous survey. Today, companies are able to extract even better performance with pyramids of about 5 μm. This speaks to the importance of the developments in the additives segment in texturing, which has not changed, however. What’s also new over the previous survey is that all leading suppliers are capable of supporting BC, which, while sharing the same fundamentals, are often ‘critical’ and ‘complex’.

A key observation in the area of emitter formation in the previous survey was that the industry was moving towards selective emitters. A lot has changed during the last year and a half. Not only were laser-doped selective emitters adopted as the standard, but they have also been pushed into obsolescence since, courtesy of laser-assisted metallization. This approach has simply decoupled the dynamics of emitter formation from metallization requirements. As a result, a few cell makers are evaluating emitters with ultrahigh sheet resistance of up to 300 Ω/sq, while the survey also has a reference to an even higher 500 Ω/sq. And thus, selective emitters have lost their relevance in the industry.

The reference technology for this survey is TOPCon, the core of which is passivation. There has been a constant race between LPCVD and PECVD for this critical step of TOPCon processing. LPCVD was the predominant technology during its days of inception, but with 2 shortcomings – external doping and wraparound. To address the latter, the industry adopted single-wafer-per-slot loading, which adversely affects the throughput. PECVD, with the ability to accomplish all the processes – application of tunneling oxide and polysilicon, and in-situ doping – addresses both these challenges. As a result, more and more cell makers started turning to PECVD, as elaborated in our previous report.

LPCVD has since staged a comeback, with updates that enabled the technology to process 2 wafers per slot and keep the wraparound within acceptable limits. As a result, now both technologies have nearly the same market share. While PVD was also known to support the core TOPCon process, it was mainly proprietary, with no tools available in the open market. A mainstream equipment supplier has recently started offering the technology commercially. Edge passivation is another development that can be classified as a passivation trend. Typically, ALD tools are used to deposit aluminum oxide here.

The most notable development not only in the field of metallization, but all along TOPCon processing, is laser-assisted metallization. This process uses a laser to form the front contacts of TOPCon solar cells. In addition to emitter optimization, as mentioned above, it also enables the optimization of metallization pastes used on the front as well as the rear. Reducing or eliminating aluminum content from the front pastes and lowering the silver loading of rear pastes are 2 examples of the positive outcomes of laser-based metallization. As for the developments associated with the tools to apply these pastes, their throughput has also increased between 15% and 25%.

Another notable development here is that stencil printing is gradually replacing the mesh screens, enabling fine-line printing. The survey includes one citation to screen openings of a mere 10 μm. As with the equipment for other process stations, the metallization segment is also running full steam on the optimization of hardware as well as the printing media for BC technology.

One process station that has remained unexcited about BC, but already thinking beyond it – read, tandem technology – is IV characterization. This segment has long been ready with the tweaks for BC. However, the hot topic in this segment is the characterization of tandem cells with sophisticated light source engineering, where each sub-cell absorbs different parts of the spectrum. LED-based light engines are enjoying a monopoly here, and their suppliers are currently making tools in high volumes for labs. No wonder then that ‘tandem’ is the buzzword in the research community.

Another notable overall improvement in the equipment segment is the increasing application of lasers. Today, lasers play a key role both in mainstream TOPCon and in BC. While lasers were used in emitter engineering for TOPCon, their role is now more relevant to establishing the contacts. In BC processing, however, lasers play a bigger role, where they accomplish the patterning. In fact, the development of lasers for patterning is the key enabler for the rollout of multi-GW production capacities built on BC cell technology.

Overall, PV is becoming increasingly progressive. While PERC was an integral part of our previous survey, published in 2023, most production equipment makers were eager to showcase their solutions for TOPCon. In the current survey, TOPCon is the mainstay, even as BC and tandem continue to grab attention. Perhaps TOPCon will become the point of reference in our next survey, like PERC 2 years ago.

This is the conclusion part of TaiyangNews latest report on Solar Cell Production Equipment 2025, which can be downloaded for free here.

We will release the subject-wise parts of the survey in our upcoming articles, published under the Technology category on our website.

TaiyangNews hosts 2 upcoming conferences in September: the Cell & Module Production Equipment & Processing Materials Conference on September 2, 2025, free registration here, and Solar Made in the USA on September 8, 2025 in Las Vegas: register via RE+ here.