Harnessing Solar Energy: Methods, Applications, and Components
Introduction to Solar Energy
Traditional energy production systems and electricity generation pose challenges, making it necessary for society to develop alternative energy sources.
The Need for Alternatives
- Hydraulic power: The greenhouse effect and climate change are leading to more prolonged droughts.
- Fossil fuel power stations: These rely on a limited resource that will eventually be depleted.
- Nuclear power plants: These present the problem of waste disposal and the risk of nuclear accidents.
Ways to Harness Solar Energy
Indirect Methods
The sun is used to heat a fluid and convert it into steam, which then drives an alternator to produce electricity.
Direct Methods
Sunlight is converted directly into electricity by solar cells and various applications.
Classification of Solar Photovoltaic Installations
Stand-Alone Applications
These are located in areas without any connection to the electrical grid. Examples include:
Space-Based Applications
Used to provide power to elements in space.
Terrestrial Applications
- Telecommunications
- Electrification of rural and remote areas
- Signaling
- Street lighting
- Water pumping
- VSAT Networks
- Telemetry
- Other applications
Networked Applications
The producer does not use the energy directly but sells it to the agency responsible for managing the country’s energy grid.
Photovoltaic and Solar Farms
Enclosures that concentrate a set number of photovoltaic systems with different properties to sell electricity to the electric company under contract.
PV in Buildings
The latest applications developed for the use of PV are integrated into buildings.
Elements of a Solar Photovoltaic Installation (SPI)
Photovoltaic Module
This essential element converts the sun’s energy into electricity (direct current). It is formed by combining different panels to provide the required power for the installation.
Charge Controller
This links the solar panels and the consumer elements of the facility. It also protects the battery against overloads and provides a DC voltage output for the installation. It sets the nominal voltage at which the installation operates.
Battery
Present only in stand-alone installations, the battery provides energy during periods without sunlight or when there is insufficient light to power the facility.
Inverter
This converts DC to AC to power devices that work with alternating current.
The Photovoltaic Solar Cell
The main element of any solar energy installation is the solar cell, which behaves like a diode.
Main Parameters of the Solar Cell
- Lighting Current: The current generated when solar radiation strikes the cell.
- Dark Current: This is due to the recombination of electron-hole pairs within the semiconductor.
- Open Circuit Voltage: The maximum voltage obtained at the ends of the solar cell when it is not connected to any load.
- Short Circuit Current: The maximum value of current that can flow through the solar cell when its terminals are shorted.
The Solar Panel
Consists of a set of cells with the following characteristics:
- Support: Provides adequate structural rigidity for installing the module.
- Connecting Cables: Found in a box on the back of the panel.
- Glass: Covers the panel and protects the solar cells from atmospheric phenomena.
- Setting: Allows installation on a given support.
- Encapsulation: Protects the module from the weather and also protects the cells and connections from potential vibration.
- Connecting: The cells are interconnected in series or parallel.
Types of Solar Panels
- Monocrystalline: 15-24% efficiency. They are uniformly blue, and the individual cells are connected to each other. They are made from pure molten material doped with boron.
- Polycrystalline: 12-20% efficiency. The glass surface is structured and contains shades of blue, similar to monocrystalline, but with fewer crystallization stages.
- Amorphous: Less than 16% efficiency. They have a uniform color (brown) but no visible connection between cells. They have the advantage of being deposited as a thin sheet on a substrate such as glass or plastic.
Power of Solar Cells
Depending on how the cells are electrically connected, we can find different possibilities:
Series Connection
Connecting cells in series will increase the final voltage at the ends of the equivalent cell.