Black technology that significantly improves conversion efficiency after PERC!

2019-11-28 11:58

The implementation of the target oriented project promotes the rapid progress and cost reduction of photovoltaic module technology in China; And the cheap and advanced photovoltaic module technology has continuously refreshed the lower bidding prices of target oriented projects, becoming a pioneering force in promoting affordable grid access!

Among the application oriented targets in 2018, the most eye-catching one, apart from low electricity prices, was the application of "a hundred flowers blooming" new technologies. 5GW winning project, all using full score components! The conversion efficiency of single and polycrystalline modules should reach 18.7% and 17.8% respectively, and the single side power of 60 modules should reach 310W and 295W. In order to achieve both "and low prices" simultaneously, almost all popular technologies have been applied:

PERC, double-sided, N-type, half piece, MBB, MWT, black silicon

It can be seen that many new technologies have accelerated from laboratories to practical applications under the promotion of guiding targets.

On the contrary, without the crazy iteration of technology, the guiding target cannot continuously demand higher conversion efficiency, nor can it generate lower electricity prices!

The guiding target has achieved new technology, and new technology has also achieved the guiding target!

However, the above technologies are relatively new. Although the total production capacity of battery cells is large, the production capacity of battery cells is still very limited due to the normal distribution of power. There is still a lot of pressure to supply 5GW of full score components within 3-4 months!

Those who have surpassed 630 know that the two key factors determining whether they can compete with electricity prices are: 1) component supply; 2) Grid connection. The 5GW application oriented benchmark project will also face these two issues if it is to be connected to the grid by the end of the year. Each base has already given a commitment letter for grid connection, will the supply of components be tight?

At present, the widely used technologies to improve conversion efficiency are mainly PERC, half chip, MBB, and black silicon (the guide marker is calculated based on the front power, so double-sided is not considered temporarily). When ordinary components are combined with these technologies, the power will be improved to a certain extent, as shown in the table below.

The component power distribution of various technical routes in 2018 is shown in Table 1.

From the above figure, it can be seen that there are only two paths to achieve full score components:

1) Adopting PERC battery technology, combined with other technologies.

PERC battery technology is a compatibility technology that can be used on both polycrystalline and monocrystalline silicon wafers. After applying PERC technology to single and polycrystalline batteries, the power will be increased by about 20W and 15W respectively. The production capacity of PERC components in 2018 was approximately 34.8GW. Among them, the production capacity of single crystal PERC components will reach 30GW; The production capacity of polycrystalline PERC components treated with black silicon technology will reach 5GW. By the end of 2018, there will be an additional 33GW of PERC production capacity, with a cumulative production capacity of 68GW!

PERC technology has become a darling among target setters due to its "low cost" characteristics. In the 2015 Targeter project, PERC components emerged as outstanding components; In the 2016 Targeter project, PERC components have become a necessary configuration for the Targeter project; Among the 2017 target players, PERC components are undoubtedly a must-have option for each company.

2) Using N-type components

In 2017, the technology and industrialization of N-type components also made significant progress. The "N-type+pert+half piece" can achieve a module power of 320W, and the production capacity is expected to be 2-3 GW in 2018; The "N-type+stacked tile" can achieve component power of over 330W, and the production capacity is expected to be within 1GW in 2018;

However, high cost has become an important limiting factor for the current development of N-type components.

Based on PERC technology, stacking half pieces and MBB is a widely adopted solution for components in the current market. However, another new technology, the "selective emitter (SE) solar cell" technology, has attracted the attention of mainstream battery panel manufacturers.

1) SE+PERC, battery efficiency effortlessly exceeds 22%

Song Zhicheng and others from State Power Investment Xi'an Solar Power Co., Ltd. once introduced in detail the "selective emitter (SE) solar cell" technology in a paper. The article believes that:

SE technology not only reduces the contact resistance between the silicon wafer and the electrode, but also reduces surface recombination and improves minority carrier lifetime by doping with high concentration at and near the contact area between the metal gate line and the silicon wafer, while also doping with low concentration in the area outside the electrode. This results in the following three obvious advantages of the battery:

(1) Reduce series resistance and increase filling factor;

(2) Reduce carrier recombination and improve surface passivation effect;

(3) Enhance the short wave spectral response of the battery, increase short circuit current and open circuit voltage.

Therefore, batteries treated with SE technology have a 0.3% improvement compared to traditional solar cells, and the combination of SE technology and PERC technology can easily exceed 22% in mass production efficiency of batteries.

2) The key is cheap!

According to the introduction of Song Zhicheng and others, upgrading from a conventional solar cell production line to a laser doped selective emitter solar cell production line requires only one step of laser doping in the process, and only adding hybrid laser equipment in the equipment, which is highly compatible with the process and equipment of conventional production lines.

Therefore, on the basis of the existing production line, SE technology can increase the existing 60 conventional components by approximately 5W with extremely low transformation costs.

3) SE technology has been adopted by multiple enterprises

It is understood that SE technology has become a hot topic of concern for battery manufacturing enterprises, and many companies have adopted this technology in battery production.

At present, frontline component enterprises such as Jingke, Longji, Jingao, Tianhe, and Aixu have all adopted this technology on a certain scale in their battery cell production, with a total production capacity of up to 12GW. Among them, Zhejiang Aixu has a larger production capacity.

It is reported that Aixu has introduced SE technology into the manufacturing of PERC batteries through the combination of "SE-PERC", using laser doping technology to form selective PN junctions. The combination of SE technology and PERC technology has enhanced the battery's absorption of ultraviolet and infrared light in sunlight, significantly improving the photovoltaic conversion efficiency of the battery. Meanwhile, all reliability tests of the SE-PERC battery meet industry standards. Since the third quarter of this year, the battery cells produced by Aixu have been able to meet the requirement of 310W full scale components.

Analysis suggests that SE, due to its low cost and significant rate improvement, is expected to become a widely adopted new technology in the industry after PERC.

From the above analysis, it can be seen that:

The introduction of guiding targets has led to rapid development of new technologies such as PERC, double-sided, N-type, half piece, MBB, MWT, and black silicon. Among them, PERC has become a widely adopted essential technology, and to achieve full score components, it is necessary to stack other technologies on top of PERC technology.

SE technology has received attention from frontline enterprises due to its low cost and significant rate improvement; The combination of "SE PERC" can easily achieve the requirement of full score components. At present, only Aixu with a large production capacity has an annual production capacity of up to 5GW. SE technology is expected to become a widely adopted new technology in the industry after PERC.

In summary, due to the production capacity of PERC reaching nearly 68GW by the end of 2018, combined with MBB, half chip, SE technology, etc., the full score component supply of 5GW by the end of the year should be very sufficient!