We define photovoltaic solar energy as the technology that can transform solar power into electricity using solar cells. PV is an acronym for photovoltaic.
This transformation takes place in the solar panels. Solar modules are made up of photocells with materials with particular electrical properties such as silicon.
The main advantages of photovoltaic technology are:
Photovoltaic solar panels do not emit greenhouse gases. Therefore, its use does not contribute to climate change and allows a sustainable development of electricity production.
It does not require fuel and feeds only on radiation from the Sun. For this reason, it is considered renewable energy.
Its sizing is scalable, and therefore, it is easy to add or remove modules according to energy demand.
Energy production can be on a large scale for general consumption or on a small scale. On a small scale, it is usually for modest houses, mountain refuges, or isolated sites.
Currently, photovoltaics (PV) is the third most used 100% renewable energy source in terms of electricity generated. On the other hand, Hydro and wind power are the renewable energy technologies that occupy the first and second positions.
How Is Solar Power Converted into Electricity?
The conversion of solar energy into electricity is carried out in photovoltaic plants.
PV plants use a tremendous amount of photovoltaic panels - or PV modules - composed of a set of solar cells. These cells are made of a material with electrons that are sensitive to solar radiation.
When photons from sunlight collide with photovoltaic cells, they cause these electrons to move, generating a DC electric current. This mechanism is called the photovoltaic effect, which is the effect that transforms solar energy into electricity.
As most of the devices work with alternating current (AC), all solar PV systems work using power converters to transform DC electricity into AC electricity.
Solar PV systems can be mounted on the ground, roof, wall, or floating on the water. The support can be fixed or be a solar tracker. Trackers have the aim to orient the panel surface with the Sun, increasing its performance.
What Is the Solar PV System's Efficiency?
Currently, the best rate of conversion of sunlight into PV energy is around 21.5%.
Depending on the construction, photovoltaic modules can produce electricity from a specific range of light frequencies. But, anyway, in general, it cannot cover the entire solar range. In particular, solar cells cannot convert ultraviolet, infrared and low light or diffuse light into electricity.
One way to increase the efficiency of solar panels would be by illuminating them with monochromatic light, much higher efficiencies could be obtained.
Therefore, another design concept is to divide light into different wavelengths. Once separated, direct them towards other tuned cells in these ranges. A photovoltaic system of this type is capable of raising electrical efficiency by 50%.
Examples of Photovoltaic Energy Use
The purpose of solar PV systems is the production of electricity that can be used in multiple applications. Here are some examples:
Generation of electric power on a large scale. There are large power plants connected directly to the electrical grid that can generate hundreds of megawatts. However, these solar farms are built using solar concentrators and function as thermal power plants.
Integrated systems on roofs and buildings. They can be for electrical self-consumption and connected to the public network.
Rural electrification is an example of how to get electricity without creating huge electrical lines. This type of solar application is used in rural villages where the power lines are very far from the population.
Some street and road lighting use solar PV systems to get electricity.
Independent systems to small power devices such as calculators, solar mobile chargers, etc.
In transportation can also take advantage of solar photovoltaics. Some electric vehicles have integrated solar systems to drive an electric motor and obtain motive power.
Communication and signaling towers that use electrical devices that do not consume large amounts of electrical energy and that are difficult to connect to the electrical distribution network.
Use in spacecraft and space stations since available energy sources are scarce in space.
Solar PV systems can be used for pumping water.
What Are the Two Types of Photovoltaic Systems?
Photovoltaic systems can be of two different types:
Photovoltaic systems connected to the public electricity grid.
Photovoltaic systems isolated from the network. This type of system is used for self-consumption and can be used in isolated homes, road lighting or other remote places.
Within the photovoltaic systems connected to the grid there are large photovoltaic plants or solar parks.
How Does It Work in Smaller Facilities?
When the energy produced is higher than its own needs, the electrical supply of the building is carried out with its power. In this case, the surplus is injected into the electrical network.
In the case of low solar radiation (for example, at night), the building is powered by the electricity grid.