Hybrid Photovoltaic Generation of Power and Nanotechnology
Recently, solar power generation is in trend, and photovoltaic technology growing massive every year. Due to which there is clean energy. In this review paper, the discussion is about the photovoltaic cells and their performance. Impact of hybrid power generation system in solar PV technology and use of nanotechnology in the field of photovoltaic solar cells.
Keywords: photovoltaic, hybrid power generation, solar cell, nanotechnology
In today’s time, renewable energy is one of the energy sources for the generation of power. As humans are using non-renewable resources on daily basis, it is going to be extinct at some point. So we are forwarding towards renewable sources of energy to overcome this situation. This is a global environmental problem which we are facing such as the greenhouse effect and acid rain are caused by massive consumption of fossil fuels such as coal and oil. Over the past decades, photovoltaic (PV) technologies have made a massive impact on the world and are used as an alternative for energy production, by converting solar energy into electrical energy. The first crystalline silicon (c-Si) based photovoltaic solar cell was demonstrated in 1954 at the Bell Labs. In the PV market, c-Si PV technology has dominated and occupied a very high market share of approximately 95% in 2019, due to its high power conversion efficiencies (PCEs), long stability, and use of non-toxic and abundant materials. Photovoltaic technology is used to generate electricity from the sunlight, which is mostly been used at remote areas to generate electricity, but now it is being widely used across the world as a renewable source of energy as it is pollution-free and does not affect the environment. There are two modes of photovoltaic inverter: stand-alone and line-interactive.
II. Features of solar photovoltaic cell
Fossil fuels are the main source of energy, and it takes around a 200million years to process the fuels present in the earth but we are using fossil fuels ever since the first extraction of fuel. This will result into the exhaustion of fuel into a mere 100 to 150 years. This is led to global warming, and the amount of carbon dioxide and Sulphur oxides has rapidly increased. The photovoltaic effects can be seen in various materials but the main component of a photovoltaic cell is a semiconductor. A semiconductor is used in converting the sunlight directly into electrical energy which is a very useful property of a semiconductor. The components that are used in the photovoltaic power generation system are cells, mechanical and electrical system connections, and regulating or modifying the electrical output of the system.
The scientist has been researching and performing various experiments with crystalline, nanocrystalline, multi-crystalline, thin-film polycrystalline, and amorphous solar cells to increase the efficiency as well as reduce the size and cost of the cells. If the thickness of the solar cell is reduced, results in an increase in open-circuit voltage. Crystalline silicon technology has been in demand due to cell performance and cost compared to other forms of cells. Also, the efficiency of the solar cells has improved over the years by the development of many multijunction devices which collects a certain wavelength of sunlight and vary it to produce electricity.
III. Hybrid photovoltaic power generation
A hybrid means a combination of two or more forms of energy to develop a new form of energy. So hybrid power generation system is the combination of a renewable energy source (PV in this case) with other forms of generating energy like wind or power generated by diesel or even renewable sources of energy so that the consumption of non-renewable fuels is reduced. Katti and Khedkar investigated the application of wind-alone, solar-alone, and integrated wind PV generation for utilization as stand-alone generating systems, to be used at the remote areas which were based on the site matching and an energy flow strategy that satisfies the need with optimum unit sizing. El-Shatter et al. designed a hybrid photovoltaic(PV)-fuel cell generation system employing an electrolyzer for hydrogen generation and applied a fuzzy regression model (FRM) for maximum power point tracking to extract the maximum available solar power from PV arrays under variable insolation conditions. Many hybrid power generation systems had been developed so far to overcome the power loss and to full fill the requirement of power. There are many scientists who has been working on many projects of these hybrid power generation system like Nelson et al, Zervas et al. which studied the hybrid power generation system and contributed in this field.
IV. Nanotechnology in solar cells
As Scientists are researching for new technologies which will be used in the generation of power energy systems. They have discovered many solutions which are a great help but there is one particular solution which is doing great and will be in high demand in the coming year i.e. photovoltaic cell. As scientists has advanced in this field they are creating something which will be of great help for future nanotechnology. There have been debates and many different points of view about nanotechnology. The difference starts with the definition. Some define it as any activity that involves manipulating materials between one nanometer and 100 nanometers. However, the original definition of nanotechnology involved building machines at the molecular scale and involves the manipulation of materials on an atomic (about two-tenths of a nanometer) scale. Nanotechnology has made an impact on the field of renewable energy sources to generate electrical energy sources. It is used in the photovoltaic cell for the generation of power. To improve the efficiency of conversion of energy, the researchers have made progress in third-generation PV cells which now absorbs more sunlight using nanotechnology, for examples ‘nanotubes’, ‘quantum dots (QDs)’, and ‘hot carrier’ solar cells.
Carbon nanotubes are molecular-scale tubes, consisting of hexagonal lattice carbon with remarkable mechanical and electronic properties. The structure of the nanotube can be represented be a vector. There are two types of nanotubes, singlewalled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs). SWNTs consist of a single graphite sheet wrapped into a cylindrical tube and MWNTs comprise an array of concentric cylinders.
B. Quantum Dots
These are the materials which have some properties which may at times lack the right absorption wavelength to make it effective with sunlight. Titania is one example. In theory, Quantum dots promises to be able to generate multiple electrons per photon. Quantum dots are very favorable as it proposes that a metallic band in the mid-gap would allow photons that have less energy than the gap energy, to be utilized by the cell. Scientists and researchers in recent years are focusing on the advancement PV conversion efficiency in third-generation PV cells using QDs, formed into an order of 3-D array for strong electronic coupling between QDs so that excitons (generate electron and hole pair) will have a longer life for collecting and transporting ‘hot carriers’ to generate electricity at higher voltage.
C. Hot Carrier Solar cells
One way of enhancing conversion efficiency is to transport hot carriers to collecting contacts before the carriers cool, called hot carrier solar cells. The second approach is to use excess kinetic energy to produce additional electron-hole pairs, called impact ionization (I.I.) in bulk semiconductors.
Non-renewable or conventional source of energy is used for the generation of power which takes time to process approximately 150 to 200 years and we are extracting fossil fuels every day and it is going to extinct sooner or later. So to overcome this issue renewable source of energy has come to light in recent years and one of that is solar energy. Solar energy is used to produce electricity which is also non-pollutant and doesn’t harm the environment, and photovoltaic technology is used to generate electricity from the sunlight. There are advancements in the generation of power and many new technologies are in process which help in generating the seamless generation. Nanotech is used in the PV cells for more absorption of sunlight into the cells so that more light rays are absorbed and more electricity is produced.