Back contact BC route drives the laser and component industry chain

     BC back contact structure development efficiency upper limit

     BC&HJT: The advantage of differentiated layout is significant, and the implementation of multiple cost reduction and

efficiency improvement technologies is accelerating.

     The BC back contact structure opens up the upper limit of efficiency and has a wide space for improvement. BC batteries

have great potential for future development in N-type technology. According to TaiyangNews data, as of September 2023, four

out of the top five high-efficiency photovoltaic modules in the industry are IBC technology battery products, led by Aixu/Longi,

with efficiencies of 24%/23.2% respectively, forming a card advantage compared to the highest module efficiency level of

23.02%/22.65% of HJT/TOPCON.

     BC: Recognized Efficient Photovoltaic Cell Technology Route

     The xBC process has high barriers, significant changes in consumables/equipment, and a long period of technological

advantage dividends:

     The concept of Back Contact (BC) was proposed in 1975 and has since evolved and improved, becoming one of the

recognized efficient photovoltaic cell technology routes in the industry.

     From the perspective of conversion efficiency, due to the absence of grid line obstruction on the front of the BC structure,

the light receiving area increases and the utilization rate of incident light is improved. Therefore, in the nearly 50 years since its

proposal, it has always maintained an absolute advantage in conversion efficiency; From an ornamental perspective, the BC

structural components have no grid line obstruction on the front, which can balance high aesthetic value and better meet the

application of diversified architectural scenes. Therefore, they are highly favored by the distributed market; From the perspective

of process compatibility, BC process is a versatile and extensible process that can be combined with TOPCon and HJT processes

to further optimize the passivation structure while fully utilizing the positive side, continuously improving battery conversion

efficiency.

     The core process flow of N-Si-based BC involves multiple laser processes

     The company has newly launched Product No. 10 with market competitiveness, which has successfully applied for a national

patent after technical testing. The 10th product will be promoted to the market in 2021. I believe this product will definitely

create a miracle in the company's sales.

     ① The production process of BC batteries is relatively long, especially the production of back electrodes, which requires 2-3

laser slotting processes and high requirements for equipment stability/process maturity. The leakage problem caused during the

laser slotting process is an important bottleneck restricting the production yield of battery cells;

     Internal system optimization

     ② Due to the overlapping of the back electrodes, corresponding adjustments need to be made in the design/welding process

and packaging process of the solder strip. In terms of welding strips, there is a trend towards flattening, thinning, and widening;

In terms of string welding machines, the welding accuracy requirements have been greatly improved, and it is necessary to avoid

warping problems during the welding process, requiring BC structure specific string welding machines. Therefore, based on

comprehensive evaluation, most manufacturers do not have TOPCon or HJT technology and production capacity to switch to BC

structured batteries at any time. Enterprises with accumulated R&D investment and rich achievements in the BC field will be able

to maintain a relatively long period of technological advantage dividends in the mass production stage.

     The BC route drives the laser equipment and component industry chain

     Multiple laser processes have been added to the battery end, significantly increasing the importance of laser equipment

     Taking the TBC route as an example, the conventional TBC process includes three laser stages. The first stage is graphical, the

second stage isolates the N/P region, and the third stage connects with metallization. The laser technology currently used in the

xBC process belongs to the subtractive method, whether it is slotting or exposure, it is aimed at removing materials.

     Component side: A new way of interconnection, with significant changes in the serial welding process

     The back electrode arrangement of BC batteries is special, and there is no need to fully utilize the effective illumination area.

The tolerance of the welding strip shape is relatively high. The component interconnection process continues the high

requirements for fine isolation of N/P areas at the battery end, with particular emphasis on local insulation treatment. The xBC

component solutions currently available in the market can be divided into flexible interconnection and rigid interconnection.