Solar photovoltaic technologies are a renewable resource that can be harnessed using a variety of different technologies. In the past, solar panels have been prohibitively expensive for homeowners to install on their homes or businesses, but prices have been falling for decades and solar panel installation costs are now competitive with other forms of electricity production.
Introduction to Solar Photovoltaic Technologies (Solar PV)
Besides the fundamental requirements of food and shelter, energy is regarded as one of the most important components in human survival. Since the beginning of human life on this planet, we have been utilizing energy in various forms. Various sources of energy have been employed; however, the most efficient ones, such as those derived from fossil fuels, have just recently been identified.
It is clear that it took millions of years for all hydrocarbon-based fossil fuels to accumulate on the planet, but mankind’s predatory consumption over the previous 200 years has depleted a significant portion of the known supplies on the planet.
Solar PV Technologies
When compared to all other options, which are also referred to as renewable due to their self-renewing nature, solar energy in the form of solar photovoltaic (PV) technologies has the most potential due to their intrinsic aptitude and versatility to be utilized in the years to come. Solar cells, like a basic leaf of any plant, which pioneered the concept of light conversion to stored energy in chemical form, transform light’s energy into the purest form of energy, i.e., electricity, which may then be used to generate any other known type of energy.
Solar Photovoltaic Technology Basics
Solar PV energy is described as the direct conversion of light into electricity through a mechanism known as the “photovoltaic effect,” which is possessed by some specific materials in specific devices known as solar PV cells or simply solar cells.
Solar cells, which convert sun radiant energy photons to direct current (electricity) without using any moving parts, are used in photovoltaic (PV) systems, which may generate hundreds of megawatts (MWp) of electricity for utility-scale power generation in a single location from a minimal (mW) range use, such as charging calculators, to hundreds of megawatts (MWp) for power generation at a utility-scale.
Solar Photovoltaic History
Solar PV energy is a promising renewable energy source that is economical, virtually limitless, and environmentally beneficial in its production. PV systems are comprised of technology that converts sunlight directly into electricity with no need for other energy sources such as fossil fuels. The term “photovoltaic” is derived from the Greek word for “solar energy.” The terms “photo” and “voltaic” refer to light and electricity, respectively.
The work of the French physicist Alexander Edmond Becquerel in 1839 is credited with the discovery of solar cells. He found the PV effect while working with a solid electrode in an electrolyte solution. He made the observation that when light landed on an electrode, a voltage was generated. Following the discovery of the photoconductivity of selenium in 1877, W. G. Adams was the first to construct a selenium solar cell, which he named after himself.
Charles Fritts created the world’s first genuine solar cell in 1883, though it was only around 1 percent effective. To produce the junction, he covered the semiconductor selenium with a very thin and transparent coating of gold, which was then coated with a very thin and transparent layer of gold. In 1927, a metal-semiconductor junction solar cell constructed of copper and semiconductor copper oxide was demonstrated, and this was the first metal-semiconductor junction solar cell.
By 1930, both the selenium cell and the copper oxide cell were being used in light-sensitive devices, such as photometers for use in photography, and both were being used in the same applications. The energy conversion efficiency of these early solar cells was less than 1 percent, making them inefficient. Finally, in 1941, Rusell Ohl developed the Si solar cell, which was patented and commercialized by the United States Department of Energy.
It was in 1954 when Bell Laboratories unexpectedly discovered that silicon doped with particular impurities was extremely sensitive to light while researching with semiconductors. This discovery marked the beginning of the contemporary era of solar energy technology. In 1954, three more American researchers, G. L. Pearson, Daryl Chapin, and Calvin Fuller, demonstrated a silicon solar cell that was 6 percent efficient when utilized in direct sunshine.
By 1958, the efficiency had improved to 14 percent, and by 1988, it had increased to 28 percent. Reynolds published the first thin-film Cu2S/CdS heterojunction solar cell with a 6 percent efficiency in the same year as the first heterojunction solar cell. Jenny published a paper in 1956 describing a GaAs solar cell with a conversion efficiency of 4%. D. A. Cusano created the world’s first thin-film CdTe solar cell based on a CdTe/Cu2Te heterojunction in 1963, achieving a 6 percent efficiency rating.
In 1972, Bonnet and Rabenhorst published a paper describing a thin-film CdTe/CdS solar cell with a 6 percent efficiency. In 1974, S. Wagner et al. published a paper describing a thin-film CuInSe2/CdS heterojunction solar cell with a conversion efficiency of 12 percent. Though significant effort in solar cell research and development remained during the 1980s and 1990s, it was during this period that public and government support for PV was under-emphasized.
Principle of Solar Photovoltaic Power Generation
In addition to solar cells, photovoltaic (PV) cells are produced from the same semiconductor materials that are used in electrical devices and computer chips. It has been proved that this energy-conversion system has a bright future because of the wide variety of PV materials available, their many potential properties, and the low cost and versatility of fabrication technologies available.
The PN junction is the primary structural component of solar cells. A junction is formed by the conjunction of a p-type semiconductor and an n-type semiconductor, which results in the formation of an electronic device. Charge flow between the p-type and n-type semiconductors can be hindered by asymmetric doping of the p-type and n-type semiconductors.
While in an equilibrium state, the flow of electrons and holes halts, resulting in a depletion area. This concentration gradient creates an electrical asymmetry situation, which is required for PV action to take place. Whenever a portion of solar cells is irradiated with light, photons of various wavelengths are absorbed by the semiconductor material.
A small percentage of photons are transformed into electrical energy because only photons with energy equal to or greater than the semiconductor’s energy band gap are absorbed. The absorption of photons results in the production of an electron-hole pair. Due to the low concentrations of Electron Hole Pairs (EHPs), the majority-carrier concentrations (the total number of electrons or the total number of holes in an n-type semiconductor or p-type semiconductor) are unaffected by extra photon contributions.
Minority carrier concentrations (the total number of electrons in a p-type semiconductor or the total number of holes in an n-type semiconductor) are, on the other hand, strongly influenced and suffer an increase in concentration. Diffusion force and electrostatic force are no longer in equilibrium as a result of this modification. Emitted electrons from the positive zone gradually diffuse into the depletion region, lowering the potential energy barrier at the junction and allowing current to flow and an electrical potential to be established at the external terminals.
It is important to note that holes formed in the n-doped zone travel in the opposite direction of holes created in the p-doped region. Solar cells function on the assumption that they are capable of producing this movement of charges. The creation of current is caused by the movement of charges in the way described above.
With the increase in coal use, there have been concerns about its environmental impact. While it is being used more widely than ever before, coal is not without its disadvantages. Some of these problems are found in the mining process itself, while others arise when it is burned to produce energy. Because of this, alternative sources are being looked into for their potential to reduce or eliminate some of these issues.