Photovoltaic Panel Structure
The most important part of a photovoltaic module is the set of photovoltaic cells that are responsible for the transformation of solar radiation into electrical energy. The rest of the elements that are part of a solar panel have the function of protecting and giving firmness and functionality to the whole.
The photovoltaic cells are encapsulated with reinforced glass and several layers of plastic material. Subsequently, all this set is reinforced by forming an outer frame with aluminum metal profiles.
The photovoltaic solar panels that are used at present are formed of the following structure:
- Front cover
- Encapsulated layers
- Support framework
- Subsequent protection
- Electrical connection box
- Photovoltaic cells
The front cover of the photovoltaic panel has a mainly protective function since it suffers the action of atmospheric agents. Tempered glass with low iron content is used, since it presents a good protection against impacts and is a very good transmitter of solar radiation.
The encapsades layers are responsible for protecting the solar cells and their contacts. The materials used (ethyl-vinyl-acetylene or EVA) provide excellent transmission to solar radiation, as well as zero degradation against ultraviolet radiation.
The EVA is a thermoplastic copolymer of ethylene and vinyl acetate, which acts as a thermal and transparent insulator to let the solar rays pass through to the photovoltaic cells. Provides cohesion to the panel as a whole by filling the existing volume between the front and rear covers, thus dampening the vibrations and impacts that may occur.
The most important problems presented by copolymers such as EVA are their excessive plasticity (when they stretch, do not recover their original position), great adherence to dust, which causes a decrease in transmissivity to solar radiation, and its low life useful, which usually affects the lifespan of the entire module.
Other features of these copolymers are:
- Good resistance to weather and chemical agents.
- Low water absorption
- Easy to paste
- Easy to cut
- Not toxic-recyclable
The support frame is the part that gives the whole mechanical robustness. The support frame of a solar panel allows its insertion in structures that will group modules.
The frame is usually made of aluminum, although it can also be made of other materials. In any case, it is important that it be constructed with a material resistant to different weather conditions.
Its mission of the posterior protection of the photovoltaic panel consists, fundamentally, of protecting against atmospheric agents, exerting an insurmountable barrier against humidity. Normally, 24 acrylic, Tedlar or EVA materials are used. They are often white, as this favors the performance of the panel due to the reflection it produces in the cells.
Tedlar, also known as PVF, Polyvinyl fluorid, or (CH2CHF) n. Tedlar or PVF is a thermoplastic polymer, structurally similar to PVC (polyvinyl chloride). It has a low flammability, low vapor permeability and excellent wear resistance due to atmospheric conditions.
Electrical connection box
Two wires come out of the electrical connection box, one positive and the other negative. It is the place where there is continuity in the electric circuit.
Some photovoltaic modules have a ground connection, which should be used in high power installations.
In the process of manufacturing the photovoltaic panel, once the electrical connections are assembled, a very strict quality control is passed, since we can not forget that they are exposed for many years to the weather in conditions from extreme heat to cold glaciers, wind, humidity, etc.
Last review: February 15, 2018