What's Hot in the Seat : ToPCoN or HJT?

??????Under the general trend of lowering the manufacturing costs and increasing efficiency of the solar module, the iterative upgrade of technology shift is happening has been going on.

This time, it's between ToPCoN and HJT. Following the huge success in the year 2020, after the P-Mono-PERC technology has completed the replacement of polycrystalline capacity, the N-type solar cells are in the next race to compete. For the moment, both ToPCoN and HJT are the most popular contenders in the rat race.?

Both, Topcon and heterojunction are the current mainstream N-type cell technology routes, and the laboratory efficiency of the two is constantly being broken, and some companies have built small-scale or even GW-level production lines.

?A clear cut comparison between the efficiency and performance, the advantages of heterojunction cells are slightly significant. ??According to technical calculations (theoretical limits), the conversion efficiency of the ToPCoN Cells is about 28% to 28.7%. The conversion efficiency of the heterojunction cells in combination with perovskite technology can reach about 29%, and the ultimate efficiency will be about 0.5% higher than that of the Topcon cells. In addition, in terms of degradation rate and temperature coefficient, the performance of the heterojunction cells is slightly better than that of the Topcon cells.

From the perspective of production line comparison between the two, the Topcon production line can be transformed from Mono-PERC production line with ease, which has a quite a high cost advantage in terms of capital investment. ?At present, the investment in ToPCoN's single GW production line is about 200 to 300 million yuan. If it is upgraded from the original production line, the cost is only between 50 million and 100 million.

In contrast, for HJT, since many equipments of heterojunction cells has not yet reached full localization, the investment of single GW typically needs 400 to 500 million yuan. ??Unless, the cost of procuring the heterojunction cell line equipment can be significantly reduced in the future, it will not be promising at all. This is a huge disadvantage and this is by-far the primary reason for the manufacturers to go ahead with ToPCoN cell technology.

It's already predicted that by the end of the year, both Heterojunction and Topcon can basically reach the pilot test line above GW, and the mass production efficiency can reach more than 24.7-25%. The top contender in ToPCoN technology like Jollywood has recently announced a huge expansion plan of 16GW in one shot which boosts the confidence of all the fellow manufacturers in China as well. Although many Tier1 companies adopt a dual line (ToPCoN & HJT) strategy in their expansion plans, when it comes to scaling, most Tier 1 choose to go for multi-GW scale for ToPCoN and for HJT, they typically restrict less than a GW pilot line.

Process wise, although HJT claims to have lesser number of steps, when it comes to the costing, ToPCoN is a clear winner, both in terms of CAPEX and OPEX. HJT CAPEX is almost 3 times higher and OPEX is 2.5 times higher compared with ToPCoN technology. Unless HJT CAPEX and OPEX costs, especially the overall silver laydown, replacement of Indium Tin Oxide with Aluminium doped Zinc Oxide, it's going to be difficult, as from the past, the solar manufacturing is always dictated and driven by the costing. Apart from this, the BOM required for HJT is extremely different from the traditional technologies, so the supply chain is not matured and competitive cost advantages is not likely to happen anytime soon.

The confidence level of Jollywood has mainly increased from the fact that from the transition from ToPCoN-1.0 to J-ToPCoN-2.0, the number of steps is precisely nine, which is very equivalent to PERC technology. Going forward, they are also working towards, J-ToPCoN-3.0, where they intend to reduce the total number of steps to seven, equalizing with HJT.

While there are huge advantages in terms of costing, maturity towards supply chain, ToPCoN yield issues are not completely addressed especially when it comes to B-doping (with both BBr3 & BCl3) due to inherent high temperature process causing too much breakages and B grades. Many scientists are working towards to solve this. Ion implantation can be a solution, but unfortunately it mayn’t be a cost-effective alternative.

In any case, the success of a technology clearly lies in the overall performance, efficiency, reliability with lowest cost $/Wp, which is what we learnt from Multi to Mono transition and same is likely to happen from P-Mono to N-Mono as well.

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