Photovoltaic Glass, What is photovoltaic glass
Photovoltaic glass speaks to what is photovoltaic glass and why use photovoltaic glass.
It is that which is coated with a thin film of amorphous silicon that generates electricity from sunlight. It allows a building with a large glazed area to create at least some of its electrical energy that it uses for lights and its building mechanical and other systems.
Photovoltaic glass is a special glass
with integrated solar cells that convert solar energy into electricity. This
means that the power for an entire building can be produced within the roof and
façade areas. The solar cells are embedded between two glass panes and a
special resin is filled between the panes, securely wrapping the solar cells on
all sides. Each individual cell has two electrical connections, which are
linked to other cells in the module, to form a system which generates a direct
electrical current.
Apart from providing privacy and protection from noise and rain, other features
such as thermal insulation and shading are becoming increasingly desirable. All
of these functionalities can be obtained simply by installing photovoltaic
glass to the shell of a building.
Theory of Operation
As seen in the science behind PV, a photovoltaic cell is created when a positively charged (P-type) layer of silicon is placed against a negatively charged (N-type) layer of silicon to create a diode and this diode is connected in a circuit via metal conductors on the top and bottom of the silicon sandwich. Though different types of photovoltaics vary in their structure, they generally include the following elements:
The cell or multiple cells are the core of the photovoltaic panel.
A glass cover is placed over the photovoltaic cell to protect it from the elements while allowing sunlight to pass through to the cell.
An additional plastic anti-reflective sheet is often used to enhance the effect of the glass cover and anti-reflective coating of the cell to block reflection.
A panel backing (typically plastic) and frame complete the photovoltaic panel, holding all the pieces together and protecting it from damage during installation.
Manufacture
The solar cells are embedded
between two glass panes, and a special resin fills between the panes, securely
wrapping the solar cells on all sides. Each individual cell has two electrical
photovoltaic modules (PVs).
A photovoltaic module or photovoltaic panel is a packaged interconnected
assembly of photovoltaic cells, also known as solar cells. The photovoltaic
module, known more commonly as the solar panel, is then used as a component in
a larger photovoltaic system to offer electricity for commercial and
residential applications.
Photovoltaic modules enable the active use of solar radiation by turning it
into electrical energy; in addition, they can also represent a form of passive
solar protection. The most well known PV products are silicon solar cells,
available in three types:
Monocrystalline
The monocrystalline solar cells
are opaque, blue, or dark grey to black, and they have a high efficiency (14%
to 16%). They are expensive because they are made from silicon crystals in a
complicated manufacturing process.
Poly- or multicrystaffine
The polycrystalline solar cells are mostly blue or opaque. These are cheaper
because they are made from poured silicon blocks, but they have a lower
efficiency (14%). Crystalline solar cells are produced as 0.4mm thick discs in
sizes from 10 x 10cm to 15 x 15cm. These discs are then put together to form
modules and embedded with resin in the cavity in a laminated glass unit.
According to composition, the result can be either a transparent, translucent
or a non-transparent module.
Light transmission through transparent and translucent modules can be set from
4% to 30% according to the choice of spacing. Special light-scattering and insulating
glass elements have been developed to meet both the needs in terms of
lighting and insulation as well as the desire to maintain and exploit the
corporate image as protected through the façade. In the exterior
laminated glass, PV cells have a 5mm gap between them. On the inside, a
laminated glass with an opaque interlayer is used.
Amorphous
Amorphous is a non-crystalline solar cells. Amorphous modules are transparent,
can be used as windowglazing
in usual windows, sunspaces, they can be integrated into roofs etc. Transparent
modules can be also part of energy
efficient glazing, where they are used instead of usual glass.
Optimized exploitation of solar energy can be achieved by combining several
thin film layers with different spectral responses. So-called tandem cells have
reached up to 12% efficiency under laboratory conditions, slightly higher
values seem possible. Further possibilities are offered by triple cells which
consist of a succession of three thin film layers Efficiencies of 10% in
production quantities are becoming realistic.
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