Frontline of Photovoltaic Technology Iteration: Unveiling the Future Battlefield of HJT, TOPCo, and BC

TOPCon batteries enter a promotion dividend period, with multiple routes coexisting to accelerate differentiated competition

In the past few decades, crystalline silicon cells have been the dominant technology in the photovoltaic market, favored for their

mature production processes, high energy efficiency ratios, and relatively long service lives. Crystalline silicon cells mainly

include two types: monocrystalline silicon and polycrystalline silicon, among which monocrystalline silicon cells occupy the

technological high ground with their higher efficiency and stability.

In 2023, a new round of capacity expansion cycle will be launched around N-type battery technology in all links of the

photovoltaic industry chain. The TOPCon technology route, due to its excellent cost-effectiveness and mature production

technology, has taken the lead in achieving large-scale production and entered a period of promotion dividends. According

to statistics, TOPCon battery modules have already accounted for 70% of the current bidding share and will gradually replace

P-type PERC modules.

At the same time, emerging photovoltaic technologies such as heterojunction (HJT), back contact (BC), and perovskite solar cells

are also rapidly developing. HJT cells improve efficiency by adding an amorphous silicon layer on top of traditional silicon cells,

while BC cells reduce frontal obstruction by placing all electrodes on the back of the cell, thereby improving photoelectric

conversion efficiency. Perovskite solar cells have become a research hotspot due to their potential for low cost and high

efficiency, although their stability and environmental impact remain challenges that need to be overcome. According to

statistics, by the end of 2023, the nominal production capacity of TOPCon/HJT/BC batteries will reach 684/51/58GW, while the

planned production capacity of perovskite batteries in 2023 is 5.5GW.

Except for perovskite cells, the photoelectric conversion efficiency of the new cells is higher than that of traditional PERC cells. Among them, BC batteries currently have the highest mass production efficiency, reaching 26.5%, and the theoretical efficiency is the highest, with a large room for improvement.

   

2. HJT batteries are limited by incompatible production lines, and the process of scaling up is relatively slow

Core principle:

The core principle of HJT battery lies in its adoption of heterostructure, which is based on traditional crystalline silicon (c-Si),

with a layer of n-type and p-type amorphous silicon (a-Si: H) plated on both sides. The key to this structure is that the

amorphous silicon layer can effectively passivate defects on the surface of crystalline silicon, reduce electron hole

recombination, improve the open circuit voltage and fill factor of the battery, thereby achieving high-efficiency photoelectric

conversion. The introduction of amorphous silicon layer not only improves the performance of the battery, but also allows for

production at lower temperatures, helping to protect the silicon wafer from high-temperature damage. However, it also brings

higher manufacturing costs and technical difficulties.

Main features:

(1) High photoelectric conversion efficiency: According to Longi's latest theoretical update in May 2023, the theoretical limit

efficiency of HJT based on nanocrystallization process can reach 29.2%, which is higher than the 28.7% based on the

double-sided Poly route TOPCon;

(2) More stable in high temperature environments: The temperature coefficient of HJT cells is better than that of PERC cells and

TOPCon cells. Currently, the temperature coefficient of conventional PERC cells is -0.45%~-0.3%/℃, TOPCon cells is generally

-0.29%~-0.28%/℃, and HJT cells is -0.25%~-0.2%/℃. In high temperature environments, HJT batteries generate more electricity

and have better power generation performance;

(3) Less process technology: The HJT battery process mainly includes four steps: velvet making, amorphous silicon deposition,

TCO deposition, and screen printing, which is much less than the process technology of PERC (10) and TOPCON (12-13), with a

large cost reduction space and high product yield.

(4) Incompatibility between the production line and the original P-type battery: The incompatibility of the production line is the

core reason why the current HJT battery market share is far lower than TOPCon, and cannot be directly converted from the PERC

production line like TOPCon batteries;

(5) The cost of silver paste is relatively high: According to Solarzoom's calculations, as of September 2023, the non silicon cost of

HJT has reached 0.22 yuan/W, which is about 0.09 yuan/W higher than PERC cells, and the silicon cost is about 0.025 yuan/W

lower than PERC cells. The comprehensive cost per watt is only 0.07 yuan/W. Low temperature silver paste is the majority of non

silicon costs, accounting for approximately 35%.

Current situation:

De silvering is an important breakthrough for HJT to reduce costs, including the use of new composite materials such as silver

coated copper or the use of electroplated copper instead of low-temperature silver paste. At the end of January 2024, Dongfang

Risheng announced that it had successfully reduced the amount of pure silver used in heterojunction Fuxi modules, reaching a

leading level of less than 7mg per watt, significantly better than PERC (about 7.82mg/w) and TOPCona (about 10.24mg/w).

The pain point of HJT's high production cost also lies in the incompatibility between the production line and the original PERC

cells. The performance requirements of the equipment are much higher than those of TOPCon cells, and the investment amount

is large, resulting in high depreciation costs for HJT cell production.

In addition, as the two major competitors of N-type batteries, the differentiation between HJT batteries and TOPCon batteries is

not obvious, and there is a certain degree of homogenization competition. It also requires additional investment and exploring

cost reduction paths. Due to various reasons, the current nominal production capacity of HJT batteries is much lower than

TOPCon batteries and lower than BC batteries.

Summary

TOPCon、HJT、BC、 Although perovskite cells have received significant attention in the current era, they cannot be compared

on the same stage due to their different stages of development and positioning properties.

From their respective perspectives, PERC, TOPCon, and HJT all aim to improve the passivation process and reduce electrical losses

to enhance the maximum conversion efficiency of the battery, and are competitive substitutes. At present, the replacement of

traditional PERC cells with TOPCon and HJT cells is the trend, while HJT cells have a relatively small market share due to their lack

of differentiation but require additional investment and cost reduction processes. It is expected that TOPCon batteries will

become the core mainstream of the photovoltaic market in 24-25 years, while HJT batteries will still occupy around 10% of the

market share.

BC batteries improve their ultimate conversion efficiency by increasing the illuminated area and reducing the angle of optical

loss, and there is no substitute relationship between them and other batteries. At present, led by Aixu Co., Ltd., it has entered the

actual delivery and use stage. Its core competitiveness lies in efficiency and aesthetics, with obvious differentiation, and is

favored by overseas high-end distributed markets.

In short, "cost reduction" and "efficiency enhancement" are the eternal themes of solar photovoltaic cell technology. TOPCon

batteries, as a new generation of compromise and seamless integration, reached their peak in the process of N/P conversion in

the second half of 2023. In the future, the technological iteration of photovoltaic modules will still exist, and we will always pay

attention to new types of photovoltaic modules.

Zhongbu Qingtian New Energy (Hubei) Co., Ltd. is a high-tech company in the new energy industry, located in the beautiful city

of Wuhan. The company relies on technical and talent support from institutions such as Wuhan University and Hubei University

of Technology, focusing on the research and development, production, and sales of photovoltaic module equipment, as well as

investment, construction, and operation of distributed photovoltaic power stations. The company team has been deeply involved

in the photovoltaic industry for more than ten years, with a production base of 10000 square meters in Wuhan, Hubei and

Changzhou, Jiangsu, and a complete sales and service network in China and overseas. We can provide global customers with

specialized services such as targeted research and development customization of photovoltaic module equipment, turnkey

projects for photovoltaic module production lines, and investment, construction, and operation of photovoltaic power stations.

The company adheres to the corporate spirit of "Chinese standards, steady and honest steps, pioneering technology, and hard

work rewarded by heaven", helps achieve the country's "dual carbon goals", and injects green technology momentum into the

global development of new energy.