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There are two components that comprise grid-connected SPI:

• Photovoltaic module or solar panel


• Inverter

SOLAR CELL

But before describing each component of an ISF, it is necessary to better understand how a solar cell works.

Photovoltaic cells are the basic part of solar panels, usually made of silicon. As mentioned above, they are responsible for transforming photon energy into electricity by means of the photovoltaic effect.

This happens because they have two layers of semiconductors, which is where the electron current is created. These behave like a diode, so that the electric current flows in only one direction.

The uppermost semiconductor layer is the cathode, or N-type semiconductor, which is comb-shaped to allow solar radiation to pass through to the semiconductor. Meanwhile, the lower layer is the P-type or anode, which is completely metallized and does not allow light to pass through. This is how an electric field is generated, and when sunlight hits the cell, electrons are released and can be trapped by the electric field, thus generating electric current. It is for this reason that solar cells are made of semiconductors, so that they act as conductors when the energy increases, and as insulators at low temperatures.

SOLAR PANEL

Once the anatomy of the solar cell is known, it is time to describe the solar panel.

A solar panel, also known as a photovoltaic module, is a set of electrically connected photovoltaic cells, encapsulated, and mounted on a support. More specifically, the parts that make up these modules are as follows:

• Support: Structure on which the photovoltaic cells are installed.


• Connection cables: Located at the back of the panel.


• Panel frame


• Wiring: The electrical connection between the solar cells, which serves to provide an adequate level of voltage and current. They can be connected in series (to increase the final voltage) or in parallel (to increase the current).


• Encapsulation: Very important to protect the panel from the weather: humidity, abrasion, UV rays, among others.

TYPES OF CELLS THAT MAKE UP PHOTOVOLTAIC MODULES

So far, three types of photovoltaic cells are known, with different electrical performances:

• Monocrystalline: Monocrystalline cells are made from pure molten silicon and doped with boron to improve properties and make it a semiconductor material. It is the one that offers the highest yield, reaching between 15-18%, although they can reach 21%.


• Polycrystalline: They are manufactured in the same way as monocrystalline, but the crystallization phases are reduced. They have a lower yield than monocrystalline, being around 12-14%.


• Amorphous: Despite operating in periods where there is low diffuse light, they offer the lowest efficiency (less than 10%).

INVERTER

As already mentioned, the type of electricity generated by photovoltaic cells, as well as the generators of solar thermal plants, is direct current. However, it is already known that the electrical grid works by alternating current, which requires a transformer, or inverter.

Not only that, the inverter is also in charge of synchronizing the generated electric wave with that of the grid.