High-density modules compete with large-size photovoltaic technology

Reducing costs and increasing efficiency is an eternal theme in the photovoltaic industry. How to achieve greater power and higher power generation? Some companies are pushing for high-density component technology, while others are seeking breakthroughs in large-size.

Under the pressure of reducing photovoltaic costs, competition on the manufacturing side has escalated again. In order to achieve higher power and maximize power generation, most photovoltaic companies have chosen the same path - large size. However, due to the limitations of component weight and supporting auxiliary materials, it is not realistic to "blindly pursue larger" sizes of cells and components. For this reason, companies in the industry have turned their attention to a new component technology - stack welding, and called it the next important process after PERC.

According to Guo Zhiqiu, R&D Director of JinkoSolar Co., Ltd., "As the name suggests, stack welding refers to partially overlapping adjacent cells and connecting the cells using traditional ribbon welding to form a series circuit. This technology eliminates the cell spacing generated by traditional welding, maximizes the use of battery area, and achieves high energy density."

The reporter learned that this type of technology is called high-density module technology in the industry, which is to reduce the distance between cells and place more cells in the same module area, thereby improving the power and conversion efficiency of the module. Stack welding, shingling, splicing, and plate interconnection technologies all use this principle. It can be said that high-density module technology has already shown a flourishing situation.

Taking the tiling technology as an example, Longi Green Energy Technology Co., Ltd., JinkoSolar Energy Co., Ltd., and Trina Solar Co., Ltd. have all launched products with this technology. In 2019, a total of 11 photovoltaic companies, including Tongwei Co., Ltd., GCL-Poly Solar Inc., Jolywood Group Co., Ltd., and Canadian Solar Inc., launched new high-density modules, involving technologies such as shingling, splicing, and interconnection of panels.

According to industry insiders, cost reduction and efficiency improvement are the eternal themes of the photovoltaic industry. In this context, the design of high-power modules has become the most concerned direction in the industry. However, high-density modules are not "sit firmly on the throne". In parallel, there is another way to increase module power - large size.

Wang Yan, director of the photovoltaic module division of the Solar Energy Research Institute of Singapore, told reporters that since 2018, more and more photovoltaic companies have begun to "make a fuss" about the size of silicon wafers, expanding the size of silicon wafers from 156.75 mm to 166 mm. So far, some companies have launched 210 mm silicon wafers.

Which is better, high-density components or large-size components?

First of all, in terms of production compatibility, high-density components have a slight advantage. At present, the specifications of high-density components are 158.75 mm and 166 mm. According to data from the China Photovoltaic Industry Association, in 2019, 156.75 mm silicon wafers are still the mainstream of the market, accounting for more than "half of the market". Several corporate executives said that based on the equipment on the current silicon wafer production line, only some fine-tuning is needed to transform from 156.75 mm to 158.75 mm or 166 mm. At the same time, the battery cell production line is also compatible. This will largely maximize the utilization of equipment transformation, making the economy prominent.

Secondly, from the perspective of technical maturity, the design of 210mm modules has not yet been fully finalized. Xu Tao, head of module research and development at Canadian Solar, said that although the area of ​​210mm silicon wafers has increased significantly compared to 166mm, its weight should not be underestimated, which leads to an increase in load risk. At the same time, auxiliary materials such as glass and frames cannot meet the supply, and the current of the modules exceeds the input current requirements of the inverter. High-density modules are upgraded from traditional modules, and some physical properties such as attenuation, hot spot risk, anti-shadowing, and load-bearing have been improved accordingly.

In addition, in terms of cost, compared with traditional components, high-density components have advantages in construction cost and total EPC cost. Guo Zhiqiu told reporters that compared with traditional 430W components, high-density components can reduce construction costs by 6.5% and total EPC costs by 1.1%. At the same time, it saves land and is particularly suitable for distributed rooftop applications.

With a series of advantages, some companies believe that high-density components will be the technical direction for increasing the power of components per unit area for a long time in the future.

The forecast of the China Photovoltaic Industry Association may confirm the above judgment. According to the forecast, the proportion of 156.75mm silicon wafers will decline significantly this year, while the proportion of 158.75mm and 166mm silicon wafers will increase significantly; in 2021, the proportion of 166mm silicon wafers will exceed 60%; in the next five years, the proportion of 210mm silicon wafers will gradually increase, but the growth rate will be slow.

However, in the view of most industry insiders, each technical route has its own advantages and disadvantages, and the ultimate choice will be left to the market.