Solar Energy
The world is constantly developing and to fuel that development, we need energy. Currently, the primary types of energy we use are non-renewable, such as fossil fuels like coal. In addition to being nin-renewable, they are also detrimental to the environment as they release greenhouse gases that destroy the ozone layer. We need to find solutions to meet the needs of our continuously advancing society. One such energy that has emerged as a frontrunner in recent years is solar power. Solar power is power generated directly from sunlight. Solar power is used for heat energy or converted into electric energy.
History:
Evidence from ancient civilisations that date back to the 7th
century shows that they used solar energy and glass to light fires. While this
is a million miles from turning solar energy into electricity, it shows that we
have long had a fascination for the sun and its power. Homes and bathhouses
that were heated by solar energy were strategically placed so that the rays
from the sun could heat the water or water tanks. In 1839, scientist Edmond Becquerel
made significant strides in solar panel research and by 1883, the first solar cell
was produced. By 1970, these inventions were used to power water heaters. By
1991, engineers began to develop silicon cells and these were soon commercialised
for domestic and industrial use.
How is solar energy created?: Solar energy is converted into electricity with the help of solar panels. Each panel has a layer of silicon cells, a metal frame and a glass casing surrounded by a special film. The panels are grouped into arrays and placed on rooftops or in large outdoor spaces. The solar cells, also called photovoltaic cells, absorb sunlight during daylight hours. Each solar cell has a thin semiconductor wafer made from two silicon layers, where one layer is positively charged, the other is negatively charged and together they form an electric field. When light energy from the sun strikes a photovoltaic solar cell, it energises the cell and causes electrons to ‘come loose’ from atoms within the semiconductor wafer. Those loose electrons are set into motion by the electric field surrounding the wafer and this motion creates an electrical current. The electricity generated is called direct current or DC electricity, which is not the type that powers most homes. Fortunately, DC electricity can easily be changed into alternating current or AC electricity by an inverter.
In modern solar panels, inverters can be configured as one inverter for the entire system or as individual microinverters attached to every panel. Once the solar energy has been converted from DC to AC electricity, it runs through electrical panels and is distributed within a house or factory to power appliances and machines. Once into the system, it works the same way as the electrical power generated by an electric utility company. Since the system remains connected to the traditional power company, one can automatically draw additional electricity from the main frame to supplement shortages from the solar panels.
Applications: Solar energy has several applications. One of the most common applications is solar water heating. A solar water heating unit comprises a blackened flat plate metal collector with an associated metal tubing that faces the sun’s direction. The plate collector has a transparent glass cover above a thermal insulation layer beneath it. A pipe connects a metal tubing of the collector to an insulated tank that stores water. The collector absorbs solar radiation and transfers the heat to the water circulating through the tubing either by gravity or a pump. The next common application is solar heating of buildings, which is done by solar radiators or collectors. Solar distillation is also used in arid semi coastal areas, where potable water is scarce. The abundant sunlight in these areas is used to convert saline water into potable distilled water and then via solar pumping, the water is pumped for irrigation.
Advantages:
Solar energy reduces our dependence on fossil fuels. In the long term, it is
cheaper than paying for electricity. Solar panels do not require much
maintenance. Jobs are created for people who install solar panels. It also
provides the ability to live grid-free if power requirements are met.
Disadvantages: The initial cost of installing solar panels is quite high. Also the
panels require a lot of space and on cloudy days, the same amount of energy
will not be produced.
