In Lenght

This is the basic organization of all historical PV modules.

The old modules of 36 cells had 2 submodules "In length", and therefore 2 by-pass diodes.

The usual modules have now 60 or 72 cells  (rarely 48, 54 or 96), with 3 by-pass diodes, i.e. 3 submodules "In Length".

With cells of 156 to 166 mm, the gives module widths of the order of 0.99 to 1.05 m in width. The length depends on the number of cells. Modules of 60 cells are about 1.62 to 1.72 m, when modules of 72 cells have 1.93 to 2.04 m length.  

In these modules, the connexion of the by-pass diodes in a junction box requires a bus in the width of the module.

In Width

Normally the modules of 96 cells should have 4 by-pass diodes.

These could have 4 sub-modules of 24 cells each, i.e. groups of 6 x 4 cell organized in width within the modules.

We don't know whether the modules of 96 cells are really constructed like that.

Twin half-cut cells .

More and more modern modules are now organized in this configuration.

This uses series of half-cutted cells. Each submodule is made of a series of 20 or 24 cells, and 2 submodules are connected in parallel, with one common by-pass diode. The advantage is that when some cells are shaded in the bottom part, the upper part of the module is still active, minimizing the electrical shading loss. Therefore in a row arrangement, these modules should be used in portrait.  

Each sub-module has 20 (or 24) cells in series. Therefore  NCells in series = 60 (or 72), i.e half the total number of cells specified on the datasheets. And the number of cells in parallel is 2.

The global sizes of these modules are comparable to the equivalent modules "in length".  

There are other technological advantages: this minimize the series resistance, and  diminishes the risk of cracks.

This technology seems to favor the efficiency: modules of a same manufacturing processes get slightly better efficiencies.

Twin third-cut cells, 5 rows .

With the increase of the cell sizes  (182 and now 210 mm), some manufacturers try to keep the PV modules close to usual sizes.

They diminish the number of rows (5 * 210 mm lead for about 1.1 m width) and use 1/3 of cells for limiting the lenght - and also the current.

The number of cells in series may be  22 + 11 + 22  (i.e. 55 cells) or 24 + 12 + 24 (60 cells), etc. It should be divisible by 5.  

This configuration requires that for the central submodule, a copper connexion strip leading the half-current of the module has to be deployed along the sub-module.  

Twin third-cut cells, 6 rows

There are also modules with big cells and 6 rows (6 * 210 mm leads to a module width of 1.32 m), with cells cut as thirds.

NB: We can also find in the database some modules with cut cells which are neither halves nor thirds cells (182 x 70 mm).  

Twin half-cut cells, 4 rows

There are also some few narrow modules with 4 rows of cells, and therefore 2 by-pass diodes.

These seem to be especially designed for grid integration.

Shingled cells

Some modules are made of shingled cells, i.e. narrow cells (1/4, 1/5, or less) which are interconnected by superposition in the same way as tiles. There is a variety of possible layouts: sometimes all the cells in series are on one row in the module length, and these rows are connected in parallel. In other cases the rows are distributed in the width of the module, with a round trip layout.

In any case, there is no information about the by-pass diodes protections.

Exotic

Some modules have still other strange configurations, which we name "exotic" in this classification.

For these special modules, where the submodules are not well defined (Shingle or exotic), the module layout model cannot be applied.

Strips in length

Strips in width

In the thin film modules  (CIGS, CdTe, amorphous)  the cells are strips of  about 10 mm width, on the full length of the module.

In some cases, the strips may also be in the width of the module.  

This means that the number of cells in series is closely related to the modules size (width or length).

Some Thin film modules have a very high number of cells  (for example first Solar CdTe: 270 cells in series for a Vmpp around 185V).    

Most of the thin film modules have one only by-pass protection diode for the whole module. This is because the connection from cell to cell is indeed distributed on the whole length of the cells, so that it is not possible to get a middle point connection. This is not a problem because a single cell is unlikely to be shaded.

When installed in a row-like system, the strips should always be disposed perpendicularly to the possible shades. In this way all cells will be partially shaded in the same way. Therefore the thin film modules are not suffering of electrical shading losses.