Monocrystalline Photovoltaic Panels

MONOCRYSTALLINE PHOTOVOLTAIC PANELS

ENGLISH REPORT


EDUARD SANZ RUIZ S11002458



SUMMARY
Photovoltaic panels are structures formed by multiple photovoltaic cells. Its function is to transform light energy into electricity. To accomplish this, they use the photovoltaiceffect.
PV panels produce energy without CO2 emissions, have no moving parts, require virtually no maintenance and have a long life, many manufacturers guarantee a lifetime of 20-25 years for their products, yet his life is in fact more. Although it seems paradoxical, high temperatures are a negative factor because it shortens its life.
For now, the main drawback of these systems is their high costand poor performance as become an alternative energy source by itself.

INTRODUCTION
The evolution of the global technology is closely tied to our capability to produce energy. For this reason the renewable energies and the clean methods to produce energy are nowadays a huge important topic.
One of the most popular renewable energy technologies is the photovoltaic. Inside this group,different types of photovoltaic panels with similar technologies are available but the most popular is the monocrystalline.
Despite they have some problems, is scheduled to be settled in a few years. In laboratory tests, photovoltaic cells have demonstrated almost twice the performance compared to currently marketed panels. Its estimate theoretical performance is still well above.
By the other hand,provides a rapid reduction in prices when the photovoltaic panels begin to be mass produced.
The different photovoltaic panels are classified depending on the semiconductor materials which have been made and the procedure that have been developed, as mentioned before. The PV panel’s technologies available in the market are:
Pure silicon monocrystalline, Pure silicon polycrystalline, Amorphoussilicon, Tandem panels, Cadmium telluride, Gallium-Arsenide, Copper indium diselenide and Copper indium gallium selenide


 
METHODOLOGY
For achieve an understanding of the different types of PV panels, is necessary to know basic concepts of the conversion from light radiation to Current.
A photon is a portion of light energy. If one photon strikes a material with a crystalline structure,it releases an electron from its initial position, giving it enough energy to move freely through the crystalline material.
Band gap is the property of a material that determines the minimum energy needed to allow that fixed electrons become free.
The temperature increase resulting from the impact of direct light, releases electrons by itself, however there are few electrons released becausethis effect.
The aim of PV panels is create movement between these free electrons in order to generate current.
This is achieved combining different semiconductor materials with different properties to form a junction. The most common junction is result of "n-type" and "p-type" combination.

 
ANALYSIS
The silicon, which element symbol is Si02, is the second most abundant element on theplanet earth and is generally found in the form of sand.

Fig. 3 Lump of pure silicon
The pure silicon monocrystalline cells usually have a uniform blue colour, and are obtained from pure silicon. In the process, they are heated at 1700ºC, once they have melted, cooled quickly to obtain a single piece of crystal of large dimensions and with a cylindrical shape. From this cylinder, many wafers arecut forming solar wafer. Due to this process called Czochralski, the solar wafers have a high quality and are nearly free of impurities; only a few parts per million.
As a result, panels configured with monocrystalline cells have a good relationship between sun irradiation and current produced, practically proportional as is shown in fig.4a.
By the other hand, this kind of panels, (and almost...