What is the Definition of Solar Energy?
With the buzz around clean energy, what is the definition of solar energy? Very simply, solar energy is a radiant energy naturally produced by the sun. If you are accustomed to enjoying sunny days you may not stop often to consider the power the earth receives from the sun.
The sun is a star. It is a huge conglomerate of mostly hydrogen gases and of helium atoms. The sun's core is hydrogen atoms which combine with the gases in a process we call nuclear fusion. We think of the sun as "burning" but the true fusion process is much stronger than just a fire.
The Science behind the Definition of Solar Energy
High pressure and temperature of the sun break apart hydrogen atoms and cause the nuclei (the center) to combine or to fuse. Thus the word "fusion".
One helium atom is created when four hydrogen nuclei fuse together. The atom created is smaller than the total of the four atoms and the excess matter is sent into space as radiant energy.
It takes only eight minutes for the energy rays of the sun to travel to earth. This is a distance of 93 million miles and the solar energy moves from the sun to the earth at 186,000 miles per second.
That's the science behind the speed of light. Only a small part of the energy traveling toward earth actually strikes the earth's surface but this small amount has an enormous effect on our planet.
Where does the energy go? Some of it is reflect back into space and about 30% of the energy evaporates water on the earth's surface and pulls that water into the atmosphere. That is the process that produces rain and snow.
The Definition of Solar Energy is Nothing New
Over one hundred years ago, a French scientist used a rough solar collector to create steam to drive a steam engine. In 1936, Charles Greeley Abbot, a U.S. astrophysicist, built an efficient solar boiler. The solar industry had its beginnings in the 1920s and was very active until the 1950s.
In the 1950's the old coal fired furnaces in homes gave way to low-cost natural gas and to oil furnaces. Because oil and gas were so cheap, solar energy was mostly ignored. This began to change in the 1970's when oil shortages led to long lines at gas stations and the cost of oil and gas began to rise.
When considering the definition of solar energy you can't ignore solar collectors. The basic definition of solar energy is the sun's rays but using that energy is not as easy as many believe.
You must capture the sunlight and put it to work. The sun's energy is spread over the surface of the earth and one specific place does not have a high energy concentration.
Other conditions affect the definition of solar energy and how it is produced as well. More energy is received at noon than at 8 am. Seasons affect the amount of energy hitting the earth as do cloudy skies and the latitude where you live.
A solar collector is one way to provide heat using the sun. If you leave your automobile in the sun on a hot summer day with the windows up, heat will collect inside the car. The sun's rays go through the glass of the car and change into heat when absorbed by the seats, dash and steering wheel.
Your car has become a solar collector but not in a good way. This is the same type of solar collector that makes greenhouses popular. A greenhouse allows the sunlight to easily move through the panes of glass and the plants and soil inside the greenhouse absorb the energy and trap the resulting heat.
What is the Definition of Solar Energy When it is Passive?
You can use passive solar heat in your home. This means the entire house becomes a solar collector. There is no special equipment, no pipes, fans or pumps involved.
A passive solar home relies on orientation of the home so that the majority of windows are facing south. The north side of such a design will have few, if any, windows.
The southern exposure is necessary because in North America the sunlight comes mostly from the south. The southern exposure provides the most sunlight into the home throughout the day and the glass expanse allows the sun's energy to easily move into the house. It's the same process that makes your car uncomfortably hot when you left it parked in full sun.
During daytime hours the collected energy is distributed throughout the house by creating open living areas. The current fashion of building home where the living, dining and kitchen are one big open living space are the perfect architectural design for use of passive solar energy.
Passive energy used to heat a home must be controlled in practical ways. Awnings or large roof overhangs can help provide shade from the hours when the sun's rays are the strongest during summer months. On cool nights, covering the southern exposure and other windows with insulated curtains helps traps the day's heat inside the home.
The heat in a passive solar home is accomplished because the suns rays heat the walls and the floors. The best solar builders will use materials for floors and walls that naturally absorb sunlight.
A passive solar home is quiet and peaceful without noisy air conditioners or furnaces turning on and off. A passive solar home is perhaps the best definition of solar energy and its potential.