158.75mm, 166mm, and 210mm, Which Is More Favored by the Market?

PVTIME - Against the background of the global trend towards grid parity, the upgrading of solar wafer size from 156.78mm to larger sizes --- including 158.75mm, 166mm, or even 210mm --- has become a controversial topic in the PV industry. Top module and cell suppliers, including Jinko, JA Solar, Trina Solar and Aiko Solar, have retrofitted their in-house cell production lines to be compatible with the full square mono 158.75mm wafers, while LONGi and Zhonghuan Semiconductor have been promoting the 166mm and 210mm wafers respectively. As the solar industry moves towards adopting larger wafers, no consensus has yet been reached between producers on wafer size.

PVInfoLink predicts that “158.75
modules” (modules with full square mono 158.75mm cells) will dominate the
market in the first half of 2020, and the market is expected to see an increase
of “166 modules” (modules with 166mm cells) in the second half of 2020 when LONGi,
Canadian Solar, and Risen Energy put their 166mm products into mass production.
However, it is still unclear whether or not more producers will follow suit.  Industry experts estimate that, by 2020, the
market share of “158.75 modules” could reach 60%, and the M2 (156.75mm) series will
become obsolete .

Source: PVInfoLink

Source: PVInfoLink

Why full square
mono 158.75mm cells will dominate the market in 2020

According to Zhiyu
Zhang, an analyst from Solarwit, “modules with full square mono 158.75mm cells are
bound to dominate the market with the constant cost decline of crystal growth
techniques, making the benefits outweigh costs while shifting pseudo-square
wafers to full square wafers. Full square wafers fit onto PV modules in an
optimal way and raises the conversion efficiency significantly.” Zhang added
that, “the 158.75mm square wafer is 3.14% larger than M2, and increases the
power of the same-size cell by around 0.15W. In other words, with little change
to the size of modules, the 158.75mm wafers raise the power output of conventional 60-cell modules from
310W to 320W, and enables 72-cell modules to reach 410W.”

In summary, module with full square
mono 158.75mm cells have a larger light receiving area and higher power output with
very little incremental cost.

Industry experts concur that the increase of wafer size is an inevitable trend,
but an excessive increase would exert great pressure on manufacturers. Retrofitting
current production lines to be compatible with 166mm and 210mm is considerably
more costly than retrofitting to 158.75mm. For 158.75mm cell production, automation
equipment and fixtures need to be adjusted, and the cost of which is rather low
when shared equally into the cost per watt; for module production, all changes are
made in the production line’s carrier and welding segments, and the sizes of
auxiliary materials including EVA, back sheet and glass will increase.

In contrast, retrofitting the production line to be compatible with 166mm
is much more costly. Cell production requires updating current automation
equipment, and purchasing of new tubular PECVD and auxiliary equipment. For the
production of 166 modules, series welding, stitch welding, laminating, and framing machinery will need to be
replaced, and the assembly line has to be upgraded and retrofitted. Data from
PVInfoLink shows that the retrofitting cost to 166mm cells and modules is 2-3
times higher than that of retrofitting to 158.75mm. This explains
why LONGi and its downstream cell factories are currently the only producers of 166mm products .

Additionally, during the mass production of 166mm and 210mm wafers and cells, solar
manufacturers will face more challenges including, (i) higher breakage rate
during the wafer slicing process; (ii) higher risk of wafer distortion; (iii) wafer
cohesion in neighboring quartz boats in the diffusion process; and (iv) lower
cell efficiency caused by uneven surfaces during the texturing and coating
processes. Although the yield of 166mm production lines can be improved through
retrofitting, it would result in a 20% loss if it’s upgraded from a 156.75mm production

Currently, through analyzing the pros and cons of each size, the market seems to be moving forward with 158.75mm as the mainstream choice. Given its advantages of low retrofitting costs, lower cost per watt, and higher power output through shifting pseudo-square wafers to full square wafers, the 158.75mm products represent the best choice for investors pursuing solar modules with higher efficiency, power output, and cost to performance.