|
|
| Line 45: |
Line 45: |
| | <br> | | <br> |
| | | | |
| − | '''⇒ '''[[Solar Main Page|'''Back to Solar Section''']]
| + | [[Solar Main Page|⇒ Back to Solar Section]] |
| | | | |
| | [[Category:Solar]] | | [[Category:Solar]] |
Revision as of 09:10, 22 July 2009
Solar Cells
A solar cell or photovoltaic cell is a semiconductor device that converts light directly into electricity by the photovoltaic effect.
There are different types of photovoltaic cells:
Single crystal silicon PV cells are manufactured using a single-crystal growth method and have commercial efficiencies between 15 % and 18 %.
Multicrystalline silicon cells, usually manufactured from a melting and solidification process, are less expensive to produce but are marginally less efficient, with conversion efficiencies around 14 %.
PV cells made from silicon ribbons demonstrate an average efficiency around 14 %.
Thin film cells, constructed by depositing extremely thin layers of photovoltaic semi-conductor materials onto a backing material such as glass, stainless steel or plastic, show stable efficiencies in the range of 7 % to 13 %. Thin film materials commercially used are amorphous silicon (a-Si), cadmium telluride (CdTe), and copper-indium-gallium-diselenide (CIGS).
Commercially available thin film modules:
- Are potentially cheaper to manufacture than crystalline cells
- Have a wider customer appeal as design elements due to their homogeneous appearance
- Present disadvantages, such as low-conversion efficiencies and requiring larger areas of PV arrays and more material (cables, support structures) to produce the same amount of electricity
Source: IEA PVPS
Solar Modules
A solar or photovoltaic module or panel is a packaged interconnected assembly of solar cells.
In order to use solar cells in practical applications they must be:
- connected electrically to one another and to the rest of the system,
- protected from mechanical damage during manufacture, transport and installation and use (in particular against hail impact, wind, sand and snow loads). This is especially important for wafer-based silicon cells which are brittle.
- protected from moisture, which corrodes metal contacts and interconnects, (and for thin-film cells the transparent conductive oxide layer) thus decreasing performance and lifetime.
The peak power output of a solar module depends on the number of cells connected and their size. Module performance is generally rated under Standard Test Conditions (STC) : irradiance of 1,000 W/m², solar spectrum of AM 1.5 and module temperature at 25°C. Solar modules are rated in peak watts [Wp] according to their output under STC. Thus, a 50 Wp module can be expected to supply 50 W of power in full sunshine. The performance is reduced by high temperatures.
Modules can be connected in series and/or in parallel depending on the system requirements. A serial connection increases the voltage, a parallel connection increases the current.
⇒ Back to Solar Section
