What is photovoltaic energy?
It is the energy produced thanks to the sun.
Solar irradiance is the measure of the amount of solar radiation that reaches the Earth’s surface
and it is measured in watts per square meter, with a total value of about 1367 W/m2, called the solar constant.
Solar photovoltaic power plant - How does energy production take place?
To convert the radiation into electricity, the panel’s solar cells leverage the photoelectric effect:
When the light hits the photovoltaic module, the photons stimulate the electrons present in the silicon of the cell,
producing a current thanks to the physical phenomenon known as the "photovoltaic effect".
Solar photovoltaic power plant-Let's go into more detail
The cells connected to each other in series form a module.
The panel is a set of modules assembled in a common structure.
The strings are linked to each other in parallel
and together form the photovoltaic generator.
What are support structures?
The panels are housed in support structures
that guarantee the correct inclination and the right orientation with respect to the sunlight.
How many types of support structures are there?
There are two types: fixed and tracker
-monoaxial: they move to follow the sun exposure every day on a horizontal rotation axis
-biaxial: they move in all directions
How many types of photovoltaic modules are there?
The three most common are:
Monocrystalline silicon
Polycrystalline silicon
Thin film
Panel efficiency can vary from 15% to 21%.
Monocrystalline silicon Uniform dark blue colored modules
with the cell’s crystals all oriented in the same direction
and arranged in an orderly manner as to form a single crystal.
Polycrystalline silicon Almost iridescent blue modules
whose cells are made of silicon crystals oriented in a non-uniform way.
They are less efficient than monocrystalline
because they attract less power for the same module surface area.
Thin film Modules that adapt to work well with diffused light or at high temperatures.
This type of module is often called amorphous silicon.
Solar panels are also divided into:
Monofacial- They capture sunlight only from the front side.
Bifacial - They capture sunlight from the front side
using direct light but also that reflected and diffused from the backside of the panel.
The latter also includes HJT panels
that leverage innovative heterojunction technology that uses amorphous crystalline silicon,
setting the world efficiency record of 24,63% in 2020.
How is electricity produced?
Junction Box On the back of the panel we find the Junction Box,
inside which the connections between the electrical metallizations of the panel
and the external cables that allow the connection between multiple panels take place.
Let's look in more detail
The panels, joined in strings, are connected to the inverter which transforms direct current into alternating current.
The inverter is a system consisting of an IGBT stack, also known as IGBT bridge (Insulated-Gate Bipolar Transistor):
a device used as an electronic switch.
It is equipped with MPPT (Maximum Power Point Tracker) algorithms:
control instruments that fix the operating voltage of the panels
in order to reach the panel’s maximum power point.
Once transformed, the alternating current is ready to be distributed through the grid.
How does the storage system work?
Energy can also be kept in a storage system that releases energy as needed:
when there is a high demand, it is able to start delivering the accumulated energy within a few seconds
during the hours when there is no sunlight it allows a continuous supply of energy
when there is a drop in demand, it is able to store excess energy in order to avoid waste.
This ensures a constant supply of energy produced by the photovoltaic system.
We are now ready to distribute energy
Through a transformer, the intensity of the current is lowered and the voltage is raised.
In this way, the current generated is fed directly into the distribution network
that will power homes and businesses.
Thanks to solar photovoltaic power plants,
we can count on an inexhaustible reservoir of renewable energy with zero emissions to power the planet.