Brief Analysis Of The Development Of Photovoltaic Stacking Technology

Stacked Gate Is a Platform Technology That Can Save Money And Improve Efficiency

The electrode structure of a traditional battery is auxiliary grid + main grid + welding ribbon. The stacked grid eliminates the main, auxiliary grid and welding ribbon, and uses triangular conductive wires and seed layers for conduction. The stacked grid has the characteristics of low resistance, silver saving, efficiency improvement, and platformization. and other advantages.

(1) Current does not need to be transmitted horizontally, but only needs to be transmitted longitudinally. The movement path becomes shorter and the resistance becomes smaller, thereby increasing component power and reducing silver paste consumption.

(2) Ultra-fine triangular conductive wires with ultra-high surface reflectivity can reduce the equivalent light-shielding area of the battery surface to less than 1%. We expect that the power of stacked grid + TOPCon components can be increased from the current 630W to 655W (2382mm*1134mm version type component), which can increase efficiency by 25-30W.

Gate stacking is a platform technology, which can be used by TOPCon, HJT, and BC, but TOPCon and BC require gate stacking more. According to our calculations, BCTOPCon gate stacking has the most significant silver reduction effect of about 5 minutes/WHJT utilizes 0BB+ 30% silver-coated copper can basically achieve the expected goal, and the stacked gate can also solve the shading problem of TOPCon double poly.

Conductive Wire Alignment Is a Difficult Process, And Grid Stacking Equipment Is The Key. The Process Flow Of Grid Stacking Is To Prepare The Seed Layer, Prepare The Triangular Conductive Wire, And Weld The Triangular Conductive Wire And The Seed Layer.

(1) Seed layer printing: The requirements of grid stacking on the electrode pattern of the battery cell are lower than those of conventional batteries, and the grid line morphology (silver paste) screen and equipment can all be reflected.

(2) Triangular conductive wire: Shichuang's triangular conductive wire has a better reflectivity by designing a better shape and surface material. The triangle angle is 59-61 degrees, and the three R angles are controlled within the range of <15um. The arc transition area accounts for a small proportion and the reflective efficiency is high. Silver aluminum is used as the reflective coating. In the visible light range, metal Ag and AI are the two metals with the highest reflectivity. At the same time, low-temperature welding can also reduce the risk of hidden cracks.

(3) Welding: How to quickly and accurately "stack" the conductive wire onto the seed layer is a technical difficulty. The width of conventional solder strips is generally above 0.2mm, and the width of conductive wires is generally below 0.15mm, so the consistency of welding direction is more difficult to control. At the same time, finer specifications will also increase the curvature of the tin layer at the bottom of the conductive wire. The bottom tin surface is an arc, which is easy to tilt and flip left and right, increasing the difficulty of welding.

In The 0-1 Stage Of The Industry, Materials And Equipment Need To Be Further Reduced In Cost.

(1) Economic efficiency: We believe that the cost of materials and equipment is relatively high in the current small-scale production of stacked grids. In the future, mass production is expected to reduce the cost per watt by 2-4 cents compared with SMBB and 0BB.

(2)Application scenarios: At present, the incense grid can theoretically increase the power of the module by 25-30W. The key is that the ingenious structural design of the triangular conductive wire can increase the secondary reflectivity of the incident sunlight.

However, in the vertical installation scenario, the incident sunlight is mostly at an inclined angle, and the power increase of the stacked grid module is based on the premise that the tilted installed sunlight is incident at a vertical angle. Therefore, in the actual application scenario, the power increase effect of the stacked grid module may be discounted to a certain extent.

(3)Industrialization progress: The tripartite cooperation among Tongwei Co., Ltd., Jingsheng Electromechanical Co., Ltd., and Shichuang Energy is expected to accelerate the industrialization of stacked grid. We believe that stacked grid is more critical to TOPCon because it is more difficult for TOPCon to use copper-containing slurries to reduce metallization costs, while HJT can achieve extremely low metallization costs through 0BB+silver-clad copper technology.

From the current progress, the biggest bottleneck in the industrialization of stacked grid lies in equipment and materials (triangular conductive wires), such as process run-through, product yield, and economy. Shichuang currently has 1GW of dual Polo+stacked grid TOPCon modules in operation.

In the future, as stacked grid modules are mass-produced and run-through + equipment costs are continuously optimized, related equipment and material suppliers are expected to benefit from the expansion of stacked grid production. We estimate that the average annual market space for equipment is about RMB 13 billion and the average annual market space for materials is about RMB 7 billion.