solarfassade.info - portal for building integrated photovoltaics

Electrical components

In terms of handling, a photovoltaic module for building integration is no different to architectural glass, with the exception of the additional wiring. PV modules can be connected via a junction box on the back or side.
Figure 1: Back-mounted and side-mounted junction box

Source: WM Baden-Württemberg

When individual solar cells are shaded, the bypass diodes integrated into the junction box bypass the particular string (row of solar cells) so as to protect the shaded cells from being irreparably damage by the voltage generated by the adjacent cells and also to minimise the loss of the affected module. Otherwise, shaded cells would consume power and could be destroyed by excessive heat build-up (hot spot effect). The bypass diode also bypasses a string if one of its solar cells is damaged in order to prevent damage to the encapsulation medium.
Figure 2: Diagram of a junction box with bypass diodes

Source: Solarpraxis 2009

All modules series-connected positive-wire to negative wire of the next module form a string. The aggregate of all modules is called a solar or PV generator.

Module wiring with each other may be housed vertically or horizontally in the substructure. The leads are routed into the building at any entry point, where the inverter connected to the mains converts their direct current into grid-ready alternating current.

Last page update: 07.02.2011