232
A. Virtuani
trackers. Glass/glass modules, having a more rigid structure, can be made unframed.
Clamps are then used to fix the modules to the mounting structures. Alternatively,
modules may use back-rails as fixation systems.
Junction box
A junction box is generally attached at the back (or edge) of the module. Inside
the junction box, the internal module circuit is bonded to the wires that are used
to connect—through special connectors—the module in series with other modules.
Junction boxes generally accommodate one or more by-pass diodes as described in
Sect. 9.1.4.
9.2.3 Advanced Module Concepts
Advanced modules concepts generally target (i) increased module performance
by reducing Cell-to-Module (CTM) losses, (ii) increased energy-yield and/or (iii)
increased reliability.
9.2.3.1 Increased Module Performance
A concept that is slowly becoming popular is using cells cut in half (half-cell modules) to reduce cell interconnection losses. In this way, the current of each module
is reduced by a factor of two and the power losses due to resistive losses and interconnections (proportional to I
2 ·R, where I stands for current and R for resistance) is
reduced by a factor of four. Assembling smaller cells with series and parallel connections has the additional advantage of making modules more tolerant to partial
shading.
Similarly, a novel concept that is gaining the interest of the industry is that of
modules made with shingled solar cells, shown in Fig. 9.8. With this approach, the
cells are overlapping, i.e. one edge of a given solar cell is stacked below that of the
next solar cell. The cells are connected by using a conductive paste (they are not
soldered); the latter is also needed to hold the cells in place. In this way, no ribbons
(and no busbars) are needed to contact the cells. The main advantage of this structure
is that it reduces nearly to zero the inactive spacing between neighbouring cells,
thereby maximizing space utilization and efficiency of a given surface.
According to a recent publication [12], using shingled solar cells could lead to
gains in terms of efficiency between 5 and 12%, depending on the electrical layout
of the cells.
For more conventional cell/module architectures some manufacturers make use
of light capturing ribbons, which are not flat, but “structured”. In this way, the light
impinging over the ribbons is reflected and scattered at different angles, increasing
the chances of total internal reflection in the sandwich structure, and the collection
of light by the neighbouring cells. With this approach, shading losses due to the
A. Virtuani
trackers. Glass/glass modules, having a more rigid structure, can be made unframed.
Clamps are then used to fix the modules to the mounting structures. Alternatively,
modules may use back-rails as fixation systems.
Junction box
A junction box is generally attached at the back (or edge) of the module. Inside
the junction box, the internal module circuit is bonded to the wires that are used
to connect—through special connectors—the module in series with other modules.
Junction boxes generally accommodate one or more by-pass diodes as described in
Sect. 9.1.4.
9.2.3 Advanced Module Concepts
Advanced modules concepts generally target (i) increased module performance
by reducing Cell-to-Module (CTM) losses, (ii) increased energy-yield and/or (iii)
increased reliability.
9.2.3.1 Increased Module Performance
A concept that is slowly becoming popular is using cells cut in half (half-cell modules) to reduce cell interconnection losses. In this way, the current of each module
is reduced by a factor of two and the power losses due to resistive losses and interconnections (proportional to I
2 ·R, where I stands for current and R for resistance) is
reduced by a factor of four. Assembling smaller cells with series and parallel connections has the additional advantage of making modules more tolerant to partial
shading.
Similarly, a novel concept that is gaining the interest of the industry is that of
modules made with shingled solar cells, shown in Fig. 9.8. With this approach, the
cells are overlapping, i.e. one edge of a given solar cell is stacked below that of the
next solar cell. The cells are connected by using a conductive paste (they are not
soldered); the latter is also needed to hold the cells in place. In this way, no ribbons
(and no busbars) are needed to contact the cells. The main advantage of this structure
is that it reduces nearly to zero the inactive spacing between neighbouring cells,
thereby maximizing space utilization and efficiency of a given surface.
According to a recent publication [12], using shingled solar cells could lead to
gains in terms of efficiency between 5 and 12%, depending on the electrical layout
of the cells.
For more conventional cell/module architectures some manufacturers make use
of light capturing ribbons, which are not flat, but “structured”. In this way, the light
impinging over the ribbons is reflected and scattered at different angles, increasing
the chances of total internal reflection in the sandwich structure, and the collection
of light by the neighbouring cells. With this approach, shading losses due to the