Photovoltaic Solar Energy
___________________________________________________________________________________________________________________________________________Photovoltaic solar energy is a methodology for obtaining electrical energy thanks to photoelectric cells.
The photovoltaic conversion is based on the photoelectric effect, that is, the direct transformation of the light energy that comes from the Sun into electrical energy.
When a certain material is illuminated with the visible part of the solar spectrum, part of the electrons that make up its atoms absorb the energy of the photons of light, thus freeing themselves from the forces that bind them to the nucleus and acquiring freedom of movement. This space left by the electron tends to attract any other electron that is free. To convert this movement of electrons into electric current, it is necessary to direct the movement of electrons creating an electric field in the material itself.
The photovoltaic conversion is based on the photoelectric effect, that is, the direct transformation of the light energy that comes from the Sun into electrical energy.
When a certain material is illuminated with the visible part of the solar spectrum, part of the electrons that make up its atoms absorb the energy of the photons of light, thus freeing themselves from the forces that bind them to the nucleus and acquiring freedom of movement. This space left by the electron tends to attract any other electron that is free. To convert this movement of electrons into electric current, it is necessary to direct the movement of electrons creating an electric field in the material itself.
Facilities
There are different types of photovoltaic solar installations according to their configuration:Autonomous or isolated installations of the power grid: allow to offer a direct current or alternating current service (equivalent to the power grid) in a location where the power grid does not reach. Autonomous photovoltaic installations are an option to provide the electric service in a reliable, safe and respectful way with the environment.
These facilities allow to offer an electric service, both at direct current (12, 24 or 48V) and at alternating current (using public (220V / 50 Hz). An autonomous photovoltaic installation can cover 100% of the electrical needs of a site, although it can have a conventional support system such as a generator. However, responsible energy consumption by the user is essential to make the most of the solar installation, so it is convenient to use low-consumption and high-performance appliances and incorporate energy-saving attitudes.
The most common applications of these facilities are:
- Electrification of homes away from the electricity grid.
- Agricultural and livestock applications: water bulge, irrigation systems, greenhouse and farm lighting, etc.
- Signaling and communications: air and sea navigation, road signs, repeaters, etc.
- Street lighting: streets, monuments, bus stops, etc.
- Water purification systems.
Installations connected to the electricity grid: where the electricity generated appears, totally or partially if there is self-consumption, in the electricity grid. It is also possible to connect a self-consumption installation with injection to the network.
Components of a photovoltaic installation
The main components of a photovoltaic solar installation are:The photovoltaic field , made up of photovoltaic modules, is the component of photovoltaic installations that captures solar radiation and transforms it into electricity at direct current. The inverter is another component of these facilities, and is responsible for transforming the direct current (12, 24 or 48V) generated by the photovoltaic installation into alternating current (220 or 230V) used by consumer appliances or the conventional electricity grid. Another element of the photovoltaic installations are the protections, equipment that disconnects the installation in the case of not detecting voltage to the network, in the case of loss of insulation, or when detecting any other operation. Other protections, in addition to those of voltage and frequency are the differentials and magnetotèrmics. The differentials protect against direct contacts, and the magnetotèrmics protect the system against overloads, avoiding as soon as the wiring or the equipment is damaged.
Installations that do not operate connected to the mains, usually add batteries or accumulators , which store the energy produced during the hours of solar radiation, and allow to have available 24 hours a day and on days of scarce radiation. In this case, they include a charge and battery regulator , which is an electronic device responsible for protecting the batteries from discharges and overloads. If overload is detected, the regulator short-circuits the plates and cuts the current flow to the batteries. In the case of discharge, notify the consumer with an alarm or cut off the supply if consumption continues.
To optimize the performance of the photovoltaic solar installations it is necessary to orient the plates to the south and tilt them to take full advantage of the solar radiation, that is done when the inclination of the plate is equal in the latitude of the site minus 10º.
