About Solar Energy

Author: D. Iverson, SolarCellDepot.com

What is Solar Energy?

All the energy that comes from the sun is called solar energy. It takes many different forms including the type that is used by plants to grow, the energy that causes evaporation of the oceans and other bodies of water, and the heating of the air that produces wind. Because we will never use up our supply of solar energy, it is called a renewable source. When we use solar energy to heat something, it is called thermal energy, and when we use it to produce electricity, it is called photovoltaic energy.

About 1000W of energy reaches the Earth at noon on a cloudless day. If you want to visualize what that energy looks like, think of the light from a 100W light bulb focused completely on a surface about the size of a piece of paper. Scientists are learning more every day about how to harness this energy for use by people. One of the most widely used methods of gathering the sun’s power is through the use of photovoltaic cells, also called solar cells. These cells are constructed from one of many different materials known as semiconductors. That means the material is not a good conductor of electricity like copper, but it is not a good insulator like glass, either. A semiconductor is somewhere between the two. Silicon (a part of sand) is the semiconductor that is used most often when making a solar cell. When sunshine hits the silicon crystals, photons in the sunlight cause loose electrons in the cell to begin to flow into an electrical current. The current follows wires that are placed within the solar cell, and the current will power whatever device is connected to the wires. It all happens without any noise, dangerous emissions, or moving parts to wear out or break down.

How Does Solar Energy Work?

A French teenager first noticed this process in 1839. People continued to be intrigued by the idea that they could produce electricity from sunlight for more than 100 years before anyone came up with a very practical way to use the knowledge. Throughout this time period, people were making lots of advances in the use of solar thermal energy and were developing solar cookers, designing solar water heating devices, and building homes that had passive solar heaters.

But it wasn’t until the race into outer space between the Soviet Union and the United States was in full swing, that solar cells came into widespread use. A satellite in space needs a source of power to enable the instruments on board to function. Sending heavy and bulky batteries into space to provide that power was not a workable solution, so scientists perfected solar cells, which could produce their own electricity. The Soviet Union first launched a satellite equipped with single solar cells in 1957. By January of the next year, the United States had linked several cells together to form a solar panel, which was used on a satellite at that time.

Early solar cells operated at about 6% efficiency, which means that they were able to harness only 6% of the total solar energy available from the sun into a useful form. Advances in the science of solar power have resulted in solar cells that perform at about 28% efficiency today. When several cells are working together in a solar panel, they can be used to provide energy for many devices including roadside call boxes, landscaping features, and other applications where it isn’t practical to use traditional electric power.

When solar panels are combined into an even larger formation called a solar array, they can provide solar power for entire office buildings, factories or homes.

The obvious disadvantage when thinking about how solar energy works, is the fact that it is not produced when the sun is not shining. Scientists are working to develop practical ways to store the energy that is made by a solar system, so that it will be available during the night and on cloudy days. Batteries used for storing solar energy are not the same as car batteries. They are called deep cycle or secondary batteries. A solar energy storage system must be equipped with the proper wiring and circuits to be sure that the batteries are not overloaded with current when the demand for power is light, or run down by too much discharge during times of heavy use. As technology advances, people will get more and more efficient at storing the energy from the sun. They will also continue to learn more about what solar energy is and how solar energy works.