Image source @ Visual China
Text | Core lithium words
In 2021, when "silicon is king", the battery has become the most "inner volume" link in the entire industrial chain, and its profits are not only squeezed dry by upstream silicon enterprises, but also faces a new round of industrial iteration in the industry.
At present, PERC is the mainstream technology of photovoltaic cells, after experiencing large-size iteration of silicon wafers, only in 2021 PERC cell manufacturers plan to increase the production capacity of 143GW, the overall production capacity reached a staggering 316GW, PERC's capacity expansion has entered the end.
In particular, the efficiency of PERC batteries is gradually approaching the theoretical upper limit of 24%, coupled with the existence of ATTENI phenomena such as PID, LID, LeTID, etc., so that the industry began to look for the next generation of alternative technologies.
Crystalline silicon heterojunction solar cells (HJTs) seem to have become the third generation of mainstream cell technology recognized by the industry due to their obvious advantages in conversion efficiency (currently more than 24%), process steps and temperatures, bifaciality, and anti-attenuation.
However, although the parameters of HJT cells are excellent, due to the fact that the production equipment is not shared with the PERC production line, a large amount of upfront fixed investment costs are required, and all the low-temperature silver paste used in production needs to be imported, which leads to a significantly higher cost of HJT at this stage.
The iteration of photovoltaic technology is fundamentally to improve efficiency and reduce costs, which is ultimately a cost-effective problem. But can the efficiency improvement brought by the HJT route at this stage really fill the large amount of equipment investment in the early stage and achieve a higher cost performance than other technical routes?
01 Theoretically a "perfect" revolution
Repeating the history of photovoltaic cell iteration, the current mainstream PERC battery belongs to the second generation of technology, before 2017, the photovoltaic industry generally used aluminum backfield BSF batteries.
With the advancement of technology, the industry gradually found that after the conversion efficiency of the aluminum backfield BSF battery reached 20%, it was difficult to further improve, subject to the all-metal structure of the back, resulting in a certain amount of efficiency loss, so the industry gradually began to develop new battery types.
Compared with BSF batteries, the perc battery back side of the increase in the passivation layer, prompting the battery surface composite rate is greatly reduced, because the back side passivation layer can increase the optical internal reflection, so the battery current ISC will also be significantly improved.
The core of the photovoltaic industry is "cost reduction + efficiency improvement" and reducing the cost of electricity. At the beginning of the birth of PERC batteries, its conversion efficiency is significantly higher than that of BSF cells, and the rate of efficiency improvement is faster, so PERC cells quickly replace BSF cells as the mainstream technology in the photovoltaic industry.
From 15% in 2017 to 86% in 2020, PERC batteries have completed the counterattack of market penetration in just three years. However, when PERC batteries become the recognized technical route of the industry, this means that there are not many points for this technology to be tapped.
As in the early stage, the current PERC battery has also reached the ceiling of conversion efficiency, and the HJT battery, which is regarded as the next generation of technology, can also easily break through the theoretical efficiency limit of the PERC battery, in addition to the HJT battery can also make up for a number of deficiencies of the PERC battery, which is called the "perfect" upgrade program of the PERC battery.
First of all, the conversion efficiency is better. If HJT becomes the mainstream technology route, its potential conversion efficiency is expected to exceed 28%, far higher than the current theoretical limit of 24% for PERC batteries. From a theoretical point of view, HJT cells can help the photovoltaic industry further improve conversion efficiency.
Second, the process is simpler. Different from the cumbersome processing process of PERC batteries, the HJT battery process has only 4 steps, which greatly reduces operating costs, and at the same time adopts the low temperature process, which has significantly improved the savings in fuel costs.
Third, the photoidogenic attenuation is lower. The 10-year attenuation rate of HJT batteries is less than 3%, the 25-year power generation decline is only 8%, and the annual attenuation rate is about 0.25%, which is significantly lower than the attenuation rate of 0.45% of HJT batteries, which leads to HJT batteries may be more durable.
In addition, in terms of operational stability and double-sided rate, HJT batteries are improved compared with PERC batteries, which can make up for the defects in PERC battery operations.
If only theoretical data is considered, then the HJT battery is undoubtedly a comprehensive upgrade for PERC batteries. According to the speed at which PERC batteries replace BSF cells, it may be as short as three years or as long as five years, and HJT cells will become the mainstream technology of photovoltaic cells.
But will everything really go so smoothly?
02 HJT's Capital Paradox
HJT batteries replace PERC batteries in order to improve efficiency, but at the same time need to pay more capital investment, which puts a question mark on the final HJT battery efficiency improvement.
More capital investment is mainly concentrated in two aspects: one is the upfront equipment investment, and the other is the higher cost of consumables.
Since the production steps of HJT batteries are only 4 steps, which is very different from traditional PERC batteries, this means that if you want to produce HJT batteries, you need to build a complete production line.
Among the four major process steps of HJT cells, amorphous silicon thin film deposition (PECVD) is the most critical step, with equipment investment accounting for 50% of the total equipment investment, and fleece cleaning, TCO preparation, and electrode preparation accounting for 10%, 25% and 15% of the total cost, respectively.
Although all the production equipment of HJT batteries has been localized, the current equipment investment amount of about 500 million yuan / GW is still a large expense. Of course, there is a lot of room for cost reduction in this equipment investment, but this is based on the basis of scale, but if it is not invested and will not produce scale, this has become a problem of "chicken or egg first", and it is not easy to reduce the cost of HJT battery equipment.
On the other hand, HJT batteries also have higher cost expenditures on consumable silver paste.
In the preparation of cells, screen printing is a key step in which the silver electrode grid structure is formed on the battery sheet for collecting and conducting current on the surface of the cell, which is a key link in determining the conductivity of the cell.
As one of the most important consumables, silver paste accounts for about one-third of the non-silicon cost of the cell, and the main material in the silver paste is composed of metallic silver, which is difficult to reduce costs, so the less silver pulp material is, the more cost advantages.
At this stage, the silver pulp consumption of mass-produced double-sided PERC cells is about 100mg/piece, while the silver pulp consumption of double-sided HJT batteries is more than 220mg/piece, and the amount of silver paste is doubled.
In addition, because the amorphous silicon layer is sensitive to temperature, the manufacturing temperature of HJT cells needs to be below 200 ° C, which means that a special low-temperature silver paste is required, which needs to be stored at -40 ° C, which must be used up once after opening, and currently mainly relies on imports.
The dependence on low-temperature silver paste further raises the cost of HJT battery consumables, although the amount of silver paste can be reduced through "no main grid, multi-main grid technology" and "silver-clad copper technology", and can reduce costs through the localization of low-temperature silver paste, but these still need to go through a long period of iteration, and even need HJT batteries to be popularized before there can be further improvement.
In addition to the high investment in HJT cells, photovoltaic cells actually have another technical route TOPCon batteries.
Unlike HJT batteries, which have to be re-purchased from the production line, TOPCon batteries can be enhanced on the basis of today's PERC battery production line, and only the thin film deposition equipment (LPCVD) needs to be added to complete the production line upgrade.
PerC battery upgrade is not only the HJT battery this way, this is where this iteration differs from the first iteration.
Compared with TOPCon batteries, the core advantages of HJT batteries are not so strong. TOPCon batteries not only break through the upper limit of the conversion efficiency of PERC batteries, but also do not require a lot of equipment investment, only a simple production line upgrade.
Although the current efficiency of TOPCon batteries is lower than that of HJT batteries, if the theoretical efficiency of the limit is calculated, TOPCon batteries may even be better, so is the significance of comprehensively building HJT battery production lines really that great?
Therefore, TOPCon batteries are most likely to be the biggest variable hindering the development of HJT batteries, and even in the future, there may be a dispute over the technical route of the battery.
03 Who is in a hurry to push HJT
PERC batteries have become the mainstream technology, but in just two years, in the case of mainstream manufacturers expanding the production capacity of PERC batteries on a large scale, is it really so urgent for the comprehensive technical subversion of the cells?
The answer is clearly no. In fact, the current mainstream PERC cell technology has been able to meet the needs of the photovoltaic "parity era", and the research on HJT cells is more about laying out the future than focusing on the present.
The market believes that 2021 is the first year of investment in HJT batteries, and the expansion scale of the industry is expected to reach 10-15GW, and it is expected to increase to 30GW by 2022.
Not to mention whether such expectations are overheated, even if such a growth rate can be achieved, the penetration rate of HJT batteries will be less than 10% by 2022 compared with the current perC cell size of about 316GW. That said, even with optimistic estimates, a comprehensive replacement for HJT batteries won't be that fast, and of course there are cases here that are more than expected.
So why is HJT currently a hot topic in the capital market? In fact, it is more of an expected hype. HJT does have the potential to become the core route of the future photovoltaic industry, but it is by no means now.
From the current capacity planning of HJT batteries, it is claimed that the production capacity planning of several GW is a new company in the industry, or a "new force for batteries", they themselves do not have the existing capacity pressure of PERC batteries, so they invest in large-scale construction of HJT battery production lines, hoping to achieve curve overtaking in HJT.
Specifically, in addition to Tongwei announced the 1GW HJT capacity plan, PERC's existing production capacity is more sufficient LONGi shares, JA Technology, Canadian Solar for HJT battery planning capacity are less than 1GW, which shows that for traditional cell manufacturers still regard HJT batteries as a reserve technology, after all, the existing PERC production line has the ability to upgrade TOPCon batteries, there is no need to rush to the HJT route layout to achieve self-revolution.
In addition to the new battery manufacturers, HJT battery popularization benefits the most is the related equipment manufacturers, because the HJT industry chain has achieved a comprehensive domestic substitution, so no matter whether the HJT battery can eventually successfully replace the PERC battery, Jiejia Weichuang, Maiwei shares, Jinchen shares and other equipment manufacturers can obtain new orders through the equipment layout of some enterprises for the HJT production line.
Although HJT batteries have the potential to replace PERC batteries, traditional cell factories have sufficient PERC production and will not quickly concentrate on HJT battery research and development. Even if the HJT battery finally gains a huge advantage, traditional manufacturers can temporarily cope by upgrading the PERC production line to TOPCon, and gradually begin to lay out new technologies.
Based on this, we believe that the iteration brought by HJT may be more of a "psychological offensive" of "new battery forces" and equipment factories, and the industry has not rapidly transitioned from the "PERC era" to the "HJT era" demand.
Investors should not focus all their energy on the news of the capacity expansion of HJT batteries, but should pay more attention to the market share of this route, only when the penetration rate of HJT batteries reaches a certain order of magnitude, it will cause trend changes and trigger trend opportunities, which is by no means something that can be done in the short term.
It's like Schrödinger's cat no one knows whether it lives or dies before it is opened, and no one knows whether this route will eventually bring about cost reduction before the HJT cell is mass-produced, which is actually a capital paradox in HJT at this stage.