L R AS Published on Sunday 6 September 2020 - n° 330 - Categories:cells, panels
Large cells and panels (part 2): history and why such a format?
The cell in 2017 had a format of 156.75 mm by 156.75 mm (M2). In the second half of 2018, Jinko Solar presented a panel with larger cells (158.75 mm by 158.75 mm). The increase in cell size
resulted in an increase in the power of the panels, but without an improvement in the technology of the panel itself.
At Intersolar 2018, Canadian Solar presented a panel with 166 mm by 166 mm cells. These dimensions were incompatible with the old production lines. It stood out from other producers. Competitors had to invest considerable sums of money to bring the same panel to market. The result was more investment, a higher price, less competitiveness. Monocrystalline specialist LONGi started producing panels with cells of this size in 2019. In September 2019, Zhonghuan Semiconductor launched an even larger cell, the M12, measuring 210 mm by 210 mm, or 12 inches. This size is typical of the semiconductor industry.
This innovation introduced "half-cut cells" and "cut-in-three cells". They address the need to reduce cell currents due to the large surface area of the wafers, as more surface area creates more current. The increase in current causes more losses if the busbar cross-section is kept constant (which would be done to avoid increasing costs). So how can losses be reduced without investing in busbars with a larger cross-section? Well, it is enough to divide the cells in two or three, so as to reduce the current per busbar (according to the principle: the losses in series increase or decrease exponentially with the current). In this way it is possible to manufacture larger panels without the higher series losses reducing the efficiency of the panel. And yet the currents are higher than before. In addition, manufacturers do not know what can happen to a panel if very high currents flow through it. Cutting the cell in half reduces the current.
In August 2020, LONGi, Jinko and JA Solar launched panels with 182 mm by 182 mm cells (M10 format) to compete with the M12. The advantage of these panels is that they conform well to the standard 60 cell panel layout (or 120 if split).
Who benefits?
Trina believes that these panels have a high production capacity. "The 210mm semi-cut cells provide a low Voc for a single panel, allowing more panels to be installed in chains than conventional panels. Depending on the climatic conditions of a region, a chain of 40 panels of 550 W can be installed, which translates into economic advantages for photovoltaic power plants, optimisation of the system's equipment, reduction of capital expenditure and a consequent reduction in the LCOE for a better return on the project's investment".
According to Ingeteam, the competition has moved from panel performance to power: more powerful panels improve energy density and reduce costs, as this reduces manufacturing and integration costs.
The Spanish project developer Diverxiatells considers that the panels have gone from 260 Wp to 400 or 450 Wp. The switch to more powerful panels therefore seems logical. This reduces the size of the plant and therefore the cost of renting the land.
These very powerful panels have two advantages: marketing. A high power panel sells better. A more powerful panel looks more modern even if the panel is not more efficient.
Increase the production capacity. A 600 W panel costs the same production time as a 420 W panel. It provides more power and reduces operating costs per $/Wp. This represents a saving for the manufacturer that is not reflected in the cost of the panel.
https://www.pv-magazine.com/2020/09/01/lights-and-shadows-of-500-w-plus-solar-panels-part-ii/
PV Magazine of1st September
