L R AS Published on Sunday 6 September 2020 - n° 330 - Categories:cells, panels

Large cells and panels (1st part): offering large formats

The announcement by manufacturers of panels of more than 500 Wp has generated widespread enthusiasm, but also scepticism among experts and those involved in the photovoltaic sector. They are now asking themselves many questions. What is behind all this?

Are more powerful panels really more advantageous? Why are they coming now?

China is betting on the architecture of ny-Perc type cells, which can achieve a high yield of 22 to 23% in production, but this is not the highest yield on the market. New technologies such as TOP-Con or the older technologies known as heterojunction, exceed these yields. PERC dominates the market. No one wants to venture outside of this well-known technology. Banks support it by financing almost exclusively PERC projects. Widespread use of PERC reduces costs.

This year at SNEC no one has shown new technologies. It seems that no one dares to innovate. It seems easier to follow the market standard, i.e. PERC, by combining it with increased power, as advocated by the major manufacturers.

The panels owe their increased power to the following factors:

- The increase in cell surface area. The power of the cell is directly proportional to the cell surface area, which is not the case for efficiency. The 800 W JA Solar panel uses 210 mm cells; each one is cut in three. The panel owes its power to its size (2.2 m by 1.7 m).

- The increase in efficiency is related to the increased size of the cells.

- The cells are often cut in two or three and then welded together. There is then a reduction in series resistance by halving the intensity of the cells (in half of the surface, there is half the current and double the voltage due to the double number of cells). This panel technology is already commonplace and is set to continue.

- Each manufacturer has a two-sided technology. It is simple to apply to a cell and saves on metals, but this leads to increased costs due to the rear window.

Thus, it appears that the increase in power comes mainly from the larger size of the panel, which is not exactly a technological breakthrough. This implies that we have no advantage in terms of efficiency.

https://www.pv-magazine.com/2020/08/31/lights-and-shadows-of-500-w-plus-solar-panels-part-i/

PV magazine of 31 August

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