•
•
15.5
•
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A typical polyester is polyethylene terephthalate (PET). Polyester isolates the
module electrically and Tedlar protects polyester from wind and weather
conditions.
A frame usually made from aluminium is put around the whole module in order
to enhance the mechanical stability.
A junction box is usually placed at the back of the module. In it, the electrical
connections to the solar cell are connected with the wires that are used to connect
the module to the other components of the PV system.
One of the most important steps during module production is laminating, which we
will briefly explain for the case where EVA is used as an encapsulant [105]. For
lamination, the whole stack consisting of front glass, the encapsulants, the interconnected
solar cells, and the back layer are brought together in a laminator, which is heated above
the melting point of EVA, which is around 120 °C. This process is performed in vacuo in
order to ensure that air, moisture and other gases are removed from within the module
stack. After some minutes, when the EVA is molten, pressure is applied and the
temperature is increased to about 150 °C. During the curing process, a curing agent, which
is present in the EVA layer, starts to cross-link the EVA chains, leading to transverse bonds
between the EVA molecules being formed. As a result, EVA has elastomeric, rubberlike
properties.
The choice of the layers that light traverses before entering the solar cell is also very
important from an optical point of view. If these layers have an increasing refractive
index, they act as anti-reflective coatings and thus can enhance the amount of light that is
incoupled in the solar cell and finally absorbed, which increases the current produced by
the solar cell.
PV module lifetime testing
The typical lifetime of PV systems is about 25 years. During these years little maintenance
should be required on the system components, especially the PV modules which are
required to be maintenance-free. Manufacturers typically guarantee a power between 80%
and 90% of the initial power after 25 years. During the lifetime of 25 years or more, PV
modules are exposed to various external stresses from various sources [106]:
temperature changes between night and day as well as between winter and
summer;
mechanical stress for example from wind, snow and hail;
•
15.5
•
•
A typical polyester is polyethylene terephthalate (PET). Polyester isolates the
module electrically and Tedlar protects polyester from wind and weather
conditions.
A frame usually made from aluminium is put around the whole module in order
to enhance the mechanical stability.
A junction box is usually placed at the back of the module. In it, the electrical
connections to the solar cell are connected with the wires that are used to connect
the module to the other components of the PV system.
One of the most important steps during module production is laminating, which we
will briefly explain for the case where EVA is used as an encapsulant [105]. For
lamination, the whole stack consisting of front glass, the encapsulants, the interconnected
solar cells, and the back layer are brought together in a laminator, which is heated above
the melting point of EVA, which is around 120 °C. This process is performed in vacuo in
order to ensure that air, moisture and other gases are removed from within the module
stack. After some minutes, when the EVA is molten, pressure is applied and the
temperature is increased to about 150 °C. During the curing process, a curing agent, which
is present in the EVA layer, starts to cross-link the EVA chains, leading to transverse bonds
between the EVA molecules being formed. As a result, EVA has elastomeric, rubberlike
properties.
The choice of the layers that light traverses before entering the solar cell is also very
important from an optical point of view. If these layers have an increasing refractive
index, they act as anti-reflective coatings and thus can enhance the amount of light that is
incoupled in the solar cell and finally absorbed, which increases the current produced by
the solar cell.
PV module lifetime testing
The typical lifetime of PV systems is about 25 years. During these years little maintenance
should be required on the system components, especially the PV modules which are
required to be maintenance-free. Manufacturers typically guarantee a power between 80%
and 90% of the initial power after 25 years. During the lifetime of 25 years or more, PV
modules are exposed to various external stresses from various sources [106]:
temperature changes between night and day as well as between winter and
summer;
mechanical stress for example from wind, snow and hail;