Is Photovoltaic Same As Solar Panels?

Solar energy has become increasingly popular as a renewable energy source. There are different technologies that utilize the sun’s energy, with two common methods being photovoltaic technology and solar panels. Both convert the sun’s light into electricity, but work in slightly different ways.

This article will provide an overview of photovoltaic technology and solar panels, comparing and contrasting how the two work. We’ll start with some background on how each converts sunlight into power that can be used in homes and businesses.

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Definition of Photovoltaic

Photovoltaic, often shortened to PV, refers to technology that converts light directly into electricity using semiconducting materials. The term “photo” means light, while “voltaic” refers to electricity, so photovoltaic combines the words and means turning light into electricity.

At the heart of photovoltaic technology are photovoltaic cells, which are made from materials called semiconductors such as silicon. When light shines on a photovoltaic cell, the photons from the light energize the electrons in the cell, causing them to break free from their atoms. This generates electricity in the form of direct current (DC).

The photovoltaic effect was first discovered in 1839 by French physicist Edmond Becquerel. The first photovoltaic module was built in 1883 by American inventor Charles Fritts, who coated selenium with an extremely thin layer of gold to form the junctions. However, the module had less than 1% efficiency in converting light to electricity.

Photovoltaic technology kept improving in efficiency over the decades and began being used in the 1950s to provide electricity to rural areas without access to the electric grid. Today it is one of the most important renewable energy technologies and continues to become increasingly efficient and affordable.

How Photovoltaic Works

Photovoltaic cells convert sunlight into electricity through the photoelectric effect. When photons from sunlight hit the photovoltaic cell, they transfer their energy to the electrons in the atoms of the cell’s semiconductor material. This energy causes the electrons to break free of their atomic bonds and flow as an electric current. The photoelectric effect occurs almost instantaneously, generating an electrical charge as soon as light hits the photovoltaic cell.

Silicon is the most common semiconductor material used in photovoltaic cells. Silicon atoms form a crystal lattice with free electrons moving around the lattice. When sunlight hits the cell, those electrons absorb the photon energy and are knocked loose from the lattice, creating electron-hole pairs. The electrons move to one side of the cell, producing an electric field across the cell that drives the electron current. Metal contact grids on the cell collect the electrons and transfer them to wires, producing usable electricity.

The more intense the light, the more electrons are generated and the greater the electric current. So photovoltaic power generation varies with the amount of sunlight hitting the cells. PV cells work even on cloudy days, just less efficiently than in full direct sunlight. The photoelectric effect will operate with any light source, but PV cells are optimized to convert the frequencies of sunlight into electricity.

Types of Photovoltaic Cells

There are three main types of photovoltaic cells categorized by the materials used in their construction:

Silicon Cells

Silicon cells are the most common type of photovoltaic cell, representing about 90% of the solar panel market. They are made from pure crystalline silicon and come in two main variations:

Monocrystalline silicon – Made from a single silicon crystal, these cells are cut into perfectly square wafers. They have the highest efficiency rates but are more expensive.

Polycrystalline silicon – Made from melted silicon fragments, these cells form a distinctive multifaceted look. They are slightly less efficient but cheaper than monocrystalline cells.

Cadmium Telluride (CdTe) Cells

CdTe cells use the semiconductor compound cadmium telluride to absorb and convert sunlight into electricity. They have lower silicon requirements and are easier to manufacture than silicon cells, making them one of the cheaper PV options. However, they have slightly lower efficiency rates.

Copper Indium Gallium Selenide (CIGS) Cells

CIGS cells are made from semiconductor materials copper, indium, gallium, and selenium. They have high absorption rates of sunlight compared to silicon, allowing them to be made into flexible thin-film cells. CIGS cells have efficiencies comparable to silicon but at lower production costs.

Definition of Solar Panels

Solar panels, also known as photovoltaic (PV) panels, are devices that convert sunlight into electricity. They are made up of solar cells, which are assembled together in modules and mounted in a frame. The solar cells contain photovoltaic material, commonly silicon, that absorbs photons from sunlight and generates an electric current.

When sunlight hits the solar cells, the photons are absorbed by the semiconductor material, causing electrons to be freed from their atoms. These free electrons can be captured and turned into an electric current. The current generated can then be used to power electrical loads or fed back into the grid.

Solar panels are designed to harvest the maximum amount of sunlight that hits their surface and optimize efficiency. Most solar panels are rectangular with anti-reflective coating and dark color, usually blue or black, which helps absorb more sunlight. The more sunlight that hits the panel, the more electricity is produced.

Solar Panel Components

Solar panels are made up of several key components that work together to convert sunlight into electricity. The main components include:

Photovoltaic (PV) Cells – These semiconductor devices are made up of silicon and convert sunlight directly into DC electricity via the photovoltaic effect.

Glass Casing – The PV cells are sandwiched between a transparent top layer of glass or plastic and a bottom layer for protection from the elements.
Aluminum Frame – An aluminum frame houses the solar cells and provides structural support. It has drainage holes to allow rain and snow to drain off.
Junction Box – The junction box on the back of the panel contains electrical connections and terminals to link panels together or to an inverter.

Additional components like diodes prevent electricity from flowing backwards and help optimize the performance and life of the solar panel. The cells, casing, frame, and junction box all work as a system to absorb sunlight and generate renewable electricity.

Connecting Solar Panels

Solar panels are connected together to form solar panel arrays. This allows the system to generate more power by combining the electricity output of multiple panels. Here is how solar panels are wired together:

Solar panels each produce DC (direct current) electricity. The solar cells within the panels are connected in series to increase the voltage. The panels are then connected in parallel to increase the current.

Parallel connections involve linking the positive terminal of one panel to the positive terminal of the next panel, and the same with the negative terminals. This combines the current while maintaining the same voltage.

Series connections involve connecting the negative terminal of one panel to the positive terminal of the next panel. This increases the overall voltage while maintaining the same current.

Diodes are added to prevent any backflow of electricity and to protect the panels. The panels are then wired to a solar charge controller, which regulates the power going into batteries or the electrical grid.

By connecting multiple solar panels together into an array, a solar power system can generate enough electricity to power homes, businesses, and grids. The modular nature of solar panels allows the system to be easily expanded as needed.

Comparing Photovoltaic and Solar Panels

Photovoltaic cells and solar panels are closely related technologies, but have some key differences. Photovoltaic (PV) cells are the semiconductor devices that actually convert sunlight into electricity. Solar panels are the full assemblies or modules that house many PV cells together in an array and include wiring, backing, framing and other components required to utilize the electricity generated by the PV cells.

Essentially, PV cells are the core technology that enables solar panels to function. Solar panels are a packaged product made up of many individual PV cells as well as other parts needed to generate useful electrical power. The PV cells within a solar panel absorb photons from sunlight and convert them into electricity through the photovoltaic effect. This electrical energy is collected and channeled out of the solar panel through wiring to be used to power electrical devices and systems.

So in summary, the key difference is that photovoltaic or PV refers specifically to the semiconductor technology that converts light into electricity. Solar panels are a commercial product that incorporates PV cells along with other components required to harness the electrical power generated. The PV cells are the essential technology that enables solar panels to produce renewable solar electricity.

Other Solar Power Technologies

In addition to photovoltaics and solar panels, there are other technologies that utilize solar power:

Concentrated Solar Power (CSP): CSP systems use mirrors to concentrate sunlight onto a receiver, generating high temperatures to drive a heat engine/turbine to produce electricity. The concentrated light is converted to heat which drives a steam turbine connected to an electrical power generator. CSP requires direct solar radiation to operate, which limits the locations where it can be used.

Solar Thermal Energy: Solar thermal collectors harness heat from the sun to directly heat water or a heat-transfer fluid in residential and commercial applications. Typical uses include heating swimming pools, domestic hot water, space heating, process heating, solar cooling, solar cooking, water desalination, and waste heat for industrial processes.

Conclusion

In summary, photovoltaic technology and solar panels are intrinsically linked. Photovoltaic refers specifically to the process of converting light into electricity using semiconducting materials. It is the photovoltaic effect that enables solar panels to absorb sunlight and generate renewable solar energy.

The photovoltaic cells are the core component of solar panels. Multiple photovoltaic cells are wired together and encased in panels to produce solar modules. While the terms are sometimes used interchangeably, photovoltaic represents the underlying phenomenon that makes solar power generation possible through solar panels.

As we have seen, photovoltaic technology has advanced considerably in efficiency and affordability over the past decades. With increased adoption worldwide, photovoltaics are playing a growing role in clean, sustainable power production. The future is bright for this innovative solar energy technology.