How did we get here?
The manufacturing process based on the wafer sizes of 156mm by 156mm (M1) and 156.75mm by 156.75mm (M2), which became standard in 2017, barely changed until about 2018 and traditional manufacturers have invested many resources in production lines based on this manufacturing process over the past years.
By contrast, new entrants in the solar manufacturing business may benefit from the “late-mover advantage”, which means they can acquire new production lines that result in more efficient modules without having to wait to amortize other older lines.
To address this competitive advantage, one of the traditional manufacturers, Jinko, introduced a module with larger cells (158.75mm by 158.75mm) with a relatively small investment in the second half of 2018. As the cell size increased, the resulting power increased proportionally, without implying an improvement in the module technology itself.
Other manufacturers decided to follow Jinko's strategy until Canadian Solar made a master move by releasing, at Intersolar 2018, a module with 166mm by 166mm cells, incompatible with the old lines, and thus distancing itself again from the rest of the solar producers. This forced competitors to invest a notable capex in order to launch the same module on the market. More capex, higher price, less competitiveness. Monocrytalline specialist Longi began producing products with cells of the same size in 2019.
At that point, a world leader in wafer production for the semiconductor industry came into play, Zhonghuan Semiconductor, which, in September 2019, launched an even larger cell, the M12, measuring 210mm by 210mm and based on 12-inch wafers, more typical of the aforementioned semiconductor industry.
It was this innovation that most consistently introduced the concept of “half-cut” and “third-cut cells”, two concepts that respond to the need to reduce cell currents due to the wafers' large site. Why? Asier Ukar, from PI Berlin, explained: “More surface, more current. More current, more losses as long as the busbar section must be kept constant (which is what would be done to avoid increasing costs). So what can be done to cut losses without investing in higher section busbars? Well, split the cells in two or three so that the current per busbar is reduced (the series losses increase and decrease exponentially with the current). In this way, larger modules can be manufactured without the higher series losses reducing the efficiency of the module. And yet the currents are greater than they were.”
A company that does not wish to be mentioned added another reason: “Manufacturers are not very clear about what can happen to the module if very high currents flow, possible degradation or disruptive phenomena are not ruled out, therefore they reduce them as a precaution.”
But it doesn't end here: Longi, Jinko and JA Solar have launched modules with 182mm by 182mm cells on the market this year to compete against the M12. The advantage of these modules is that they conform well to the standard layout of the 60-cell module (or 120 if they are split) and therefore do not introduce unusual dimensions that generate headaches for manufacturers of mounting structures or trackers.
We have asked several manufacturers, IPPs, distributors, developers and EPCs if these modules are really more interesting than the standard ones.
Representatives from Chinese panel manufacturer Trina told pv magazine that “these modules, in addition to having a high energy production capacity, provide advantages to the user due to their electrical characteristics. 210mm half-cut cells result in low Voc for a single module, allowing more modules to be installed in strings than conventional panels. Depending on the climatic conditions of a region, we can reach up to 40 modules in a string for 550 W modules and this is reflected in economic advantages for photovoltaic plants, in the optimization of system equipment, in the reduction of capex and in the consequent reduction of the LCOE for a greater return on investment of the project.”
According to Spanish inverter maker Ingeteam, traditional competition for module efficiency has been transferred to the variable of power. “These modules are more powerful, improve energy density and optimize costs. The trend in the market is precisely that, increasing power to reduce manufacturing costs (frames, glass), integration (structure, number of trackers, anchors and wiring).”
Spanish infrastructure project developer Diverxiatells stated that “relatively recently the conventional module was 260 Wp, today we are implementing 400-450 Wp modules in our projects. Therefore, the move to ultra-powerful modules seems to us a natural evolution of technology and its implementation would allow us to reduce the size of the strings, consequently reducing wiring and the number of solar trackers in photovoltaic plants. This reduction will also mean a smaller surface area and a lower rental cost, thus increasing the IRR of the project.”
So, analyzing the responses of all the companies that have responded to pv magazine, we have come to the conclusion that there are two points that motivate manufacturers to launch these ultra-powerful modules:
- Long live marketing!
A high power module sells more. It is like a car that goes faster. Many developers think so, because they see a higher power module as more modern. But it turns out that these advances are not seen either in efficiency or in other indicators. The only thing that manufacturers do is increase the surface of the wafer, that is to say: more surface, more power, but not necessarily more efficiency, industry representatives point out. In case any reader still has doubts, here is an apt comparison: Which animal is stronger, the ant (it is capable of lifting up to 50 times its weight) or the elephant (which can carry up to 9,000 kg)? Clearly the ant, right? Conclusion: having more power does not mean a better module.
- Increasing production capacity
The largest and most powerful module manufacturers can announce loudly that their production capacity in MW or GW is increasing. Manufacturing a 600 W module costs you the same time as manufacturing a 420 W one, with which you can get much more power in the same time and thus reduce specific operating costs in $/Wp, respondents explained. In other words, it represents a saving for the manufacturer which, by the way, is not reflected in the cost of the module. “Very smart,” they agreed.
In the next article we will see the doubts that these types of modules generate among experts.
*The article was amended on Sep. 2, 2020, to reflect that Canadian Solar launched a product based on 166 mm wafer a year before Longi.
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