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Last updated: 4 April 2002

Photovoltaic (PV) module, the basic building block of PV systems

A PV module is composed of interconnected cells that are encapsulated between a glass cover and weatherproof backing. The modules are typically framed in aluminium frames suitable for mounting. The PV module is the basic building block of any PV power system. The term "solar panel" is often used to refer to a PV module. However, the same expression is also used in reference to solar water heating systems, so to avoid confusion, "photovoltaic module" is preferred.

The performance of a module depends on the cell material. The conversion efficiency of amorphous silicon modules varies from 6 to 8%. This means that at an irradiation of 1 000 W/m2, an amorphous module will produce 60 to 80 W/m2. Modules of multicrystalline silicon cells have a conversion efficiency of about 15%. Monocrystalline silicon modules are the most efficient; their conversion efficiency is about 16%. Typical sizes of modules are 0,5 x 1 m2 and 0,33 x 1,33 m2, made up of about 36 cells. However, modules of any desired size can be produced. The modules have a transparent front sheet, which is glass or plastic. The back can be opaque. Glass and Tedlar, a plastic that is available in both transparent and opaque, are frequently used. Because of the aforementioned properties of amorphous silicon, modules of this material can have various forms and sizes, though most of the commercially available modules are rectangular and composed like the crystalline ones. Furthermore, amorphous silicon can be deposited on, e.g., windows, metal sheets, plastics and roof tiles.

Standard rectangular modules can be delivered with or without frame. Frameless modules, or laminates, can essentially be processed as normal glass panes. Special attention has to be paid to water tightness, cabling, and shading of the module surface. The thickness of glass-Tedlar laminates is generally 8 mm. Glass-glass laminates are generally at least 10 mm thick.
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Set-up of a small grid-connected PV systems

Photovoltaic (PV) systems

PV modules are connected in series and parallel to form an array, thus increasing total available power output to the needed voltage and current for a particular application. For connecting the PV modules either in series or parallel, most PV modules are equipped with a junction box at the rear side. These boxes are, in general, 5 to 7 cm deep. In larger PV power systems PV arrays are connected either in series or parallel again, depending on the required input power of the selected inverter.

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