Solar power: a promising renewable energy source

The two main types of solar renewable energy are electricity and heat. Solar cells use the photoelectric effect to convert sunlight directly into electricity. Solar collectors absorb sunlight and use its thermal energy to heat a fluid. There are many advantages to using solar renewable energy, including its free and limitless supply, but also a few disadvantages, including a high initial cost.

Solar cells do not use thermal energy to create electricity, like coal and nuclear power, but instead create it directly from sunlight. The process begins when a light photon is absorbed by an atom in a solar cell. The photon gives one of the atom’s electrons enough energy to break free of its orbit around the atom. This is called the photoelectric effect. Most solar cells are made from wafers of pure silicon that have small amounts of other elements added. These convert the silicon into a semiconductor and create the electrostatic field needed to draw the free electrons to the surface of the cell, where they are collected by thin wires and flow out of the panel as electricity.

The construction of a solar collector depends on the fluid it is designed to heat, with ducts used for air and pipes used for water. The pipes may also be contained in an insulated box that traps heat and increases efficiency. The collectors often have a matt black finish to absorb more sunlight because other colors reflect part of the sunlight away. Passive collectors use the thermosiphon effect to move the fluid around the system, while active collectors use a pump. The thermosiphon effect occurs when fluid is heated and becomes lighter, rising above the heavier colder fluid which is forced down by gravity. The heated fluid eventually cools and falls, creating a cycle that continues until the heat source is removed. The fluid is usually air or water but can be other gases or liquids. Solar collectors are commonly used for domestic hot water and pool heating, but can also be used for space heating and air conditioning in specially designed building.

There are many advantages to using solar renewable energy. The main one is the free and limitless supply of energy provided by our sun which will last billions of years. Solar panels and collectors do not produce any pollution and they are resistant to damage and corrosion. They have no moving parts, other than the small pumps used in active collectors, and they produce no significant noise. Even the pumps can be powered by solar panels. Solar panels and collectors are low maintenance and can operate for over twenty years without needing to be replaced. Almost all places on Earth have useful levels of sunlight, except the polar regions which have several months of total darkness. Solar renewable energy is even used by spacecraft and is the main power source for the International Space Station.

The disadvantages of solar renewable energy include the high initial cost of buying and installing solar panels and collectors, and their unattractive appearance. It can be a challenge making them fit it with the architecture of most buildings because their large size makes them stand out. Solar panels cannot be painted over, and solar collectors should remain black to absorb the most amount of sunlight. While they do not produce pollution when operating, the manufacture of solar panels and collectors requires large amounts of energy and causes a small amount of pollution. However, these are insignificant compared with the energy and pollution saved over their working life. Perhaps the greatest problem with solar renewable energy is the lack of it at night, but this is largely overcome by storing the excess energy produced during the day.

Solar renewable energy is a fast growing industry that has already created millions of jobs and generated billions in revenue. The demand for solar is accelerating as energy costs rise, and solar will be a source of energy well in the future, as fusion power is several decades away. The growing acceptance that climate change is a problem that needs immediate attention will see even more emphasis placed on solar as a way of reducing our dependence on polluting energy sources.

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