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blocking I
diode

Figure 5.16. Use of a blocking diode to ensure one-way current flow in a module.

5.6 MODULE STRUCTURE

Solar arrays are often used in harsh and remote environments, where supplying power
by central grid or fuel-dependent systems is not feasible. Hence, modules must be
capable of extended, maintenance-free operation. Module lifetimes of around 20
years are normally quoted by manufacturers, although the industry is seeking 30-year
lifetimes. Encapsulation is the main factor affecting solar cell life expectancy (King et
al., 2000). A typical encapsulation scheme is shown in Fig. 5.17.

glass

EVA
cells
EVA
Tedlar

Figure 5.17. A typical laminated module structure.

The Australian Standard for Installation of Photovoltaic (PV) Arrays (Standards
Australia, 2005) makes reference to IEC Standard 61215 (IEC, 1993) which is widely
used by module manufacturers to ensure that modules continue to perform under
extreme, but not unlikely, environments. The IEC 61215 tests require eight modules

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