November 21, 2018 Source: OFweek Solar Photovoltaic Network

As the photovoltaics enter a new era of upgrading and efficiency, the trend of high efficiency in the industry is becoming more and more obvious. On November 18th, Tongwei Solar's 3.2GW high-efficiency crystalline silicon battery production line was put into production. At the same time, a 1GW ultra-efficient heterojunction battery project was held.

From P-type to N-type, from PERC to heterojunction, from IBC to tiling... Unconsciously, all kinds of high-efficiency batteries have become the focus of the photovoltaic industry. Among them, the promotion and rise of PERC battery technology is especially amazing. Since entering the line of sight in the front-runner project in 2015, PERC technology has developed rapidly. At present, PERC components have occupied the mainstream market.

After the PERC, the heterojunction seems to be the next technology.

What is a heterojunction high efficiency battery?

Heterogeneous solar cells are the HIT batteries commonly used in the industry. They were first introduced and commercialized by Sanyo in Japan in 1997. Unlike conventional battery p-n junctions, which consist of crystalline silicon of the same material with opposite conductivity types, the p-n junction of a heterojunction cell consists of two different semiconductor materials, amorphous silicon/crystalline silicon. Compared with traditional monocrystalline silicon solar cells, it has higher conversion efficiency; and it does not require high-temperature furnace tube preparation, which can reduce production energy consumption and shorten preparation time. It has the advantages of generating electricity after the light is applied to the front and back, low temperature manufacturing process to protect the carrier life, high open circuit voltage, and good temperature characteristics.

At present, the highest efficiency record of heterojunction batteries has reached 26%, and theoretically there is a higher efficiency improvement potential than other battery technologies. In addition, the double-sided power generation characteristics of the heterojunction battery are also in line with the current trend of double-sided power generation.

Previously, due to the high initial investment in equipment and strict requirements on process technology, most domestic manufacturers are still waiting to see the heterojunction battery technology. However, with the continuous promotion of PERC technology, high-efficiency batteries have become the mainstream of the market. The market is increasingly demanding for battery efficiency, and heterojunction solar cells are beginning to be favored by companies.

Enterprise vying for layout

In fact, Tongwei Solar's layout of heterojunction batteries has long been in action. In May this year, Tongwei Solar signed a strategic cooperation agreement with Shanghai Microsystems and the Three Gorges Capital for the industrialization of heterojunction solar cells. It is understood that the purpose of the combination of the three strong is to accelerate the industrialization of heterojunction batteries. It is expected that the mass conversion efficiency of the mass-produced heterojunction solar cell will exceed 23%, and the component power produced by the battery is expected to reach 500W, which is more than 40% of the current high-efficiency components. At present, this plan has been put on the agenda in the near future, and the project has started construction.

Tongwei Solar is not the first company to layout heterojunction battery technology, nor will it be the last one. In July 2018, Zhejiang Aikang Technology Heterojunction Solar Cell Project started smoothly. It is expected that the battery efficiency will reach more than 23% and the production capacity will reach 5GW.

In October 2018, Zhongzhi (Taixing) Power Technology Co., Ltd., Hekou District of Dongying City, Shandong Province and Shandong Jiade Engineering Consulting Group Co., Ltd. signed a strategic cooperation framework agreement. The three parties will set up a manufacturing enterprise with heterojunction solar cells as the core. The company will build 8 high-efficiency heterojunction solar cell module production lines in three phases within three years, and complete 1GW production capacity; among them, the first phase of two 150MW production lines Construction started during the year and was completed in October 2019.

 

In general, heterojunction solar cells have attracted much attention in the global photovoltaic field due to their low preparation temperature, double-sided power generation, and low temperature coefficient, and have become one of the hot spots in the industry. Domestic enterprises such as Jinneng, Zhongzhi Power, Hanergy, and Fujian Lanshi have achieved mass production of heterojunction batteries, and new enterprises such as Aikang and Rainbow are also laying out new capacity for heterojunction batteries.

However, on the whole, the domestic heterojunction battery production line has not yet formed a large-scale production capacity, and Japan Sanyo Co., Ltd., the originator of the heterojunction battery, already has a 1GW production line, and the mass production efficiency is 23%. In this regard, Chinese companies still have a long way to go.

summary

At present, whether it is a component or a battery, "high efficiency + double-sided power generation" is the current hot spot. The heterojunction battery technology not only has higher efficiency and potential for improvement, but also has the characteristics of double-sided power generation, which fully conforms to the current trend of industry development. However, it is worth mentioning that the power generation cost of heterojunction batteries is still higher than that of ordinary crystalline silicon cells, and the key to achieving low-cost mass production is localization of equipment, improvement of yield and productivity, and reduction of silicon wafers and low-temperature silver. Costs such as pulp, TCO target and cleaning and texturing chemicals.

Therefore, it is the process cost problem that restricts the future development of heterojunction cells. Only when the cost is reduced can the market be gradually occupied. However, similar to the PERC technology of the previous two years, heterojunction battery technology has attracted the attention of many PV companies, which will accelerate the process of localization of equipment, thinning of silicon wafers, and consumption of low-temperature silver paste. It is expected to be greatly reduced, and the future will be greatly developed!