The Abundance of Solar Energy
There is only one limitless source of energy in existence. The abundance of solar energy makes it one of the most valuable natural resources that we have. It is the cleanest source of energy we have today, and it is renewable. It replenishes itself every second. Regardless of how much solar energy is captured, it doesn't put a dent in the energy that is still available.
It isn't a matter of just having solar energy available. What is important is tapping into that powerful source of energy. If technology continues to improve, there is enough energy to power every home, vehicle, plane, and business in the world a thousand times over. The challenge is capturing enough energy when the sun is shining; and having the proper storage capacity for storing it, for use when the sun isn't shining.
Solar energy is captured through solar cells, which are made of a special semiconductor material. These solar cells are also called photovoltaic cells. Simply put, these photovoltaic cells are made up of a thin wafer of semiconductor material that is specially treated to form an electric field. This field is positively charged on one side and negatively charged on the other. Electrons are knocked loose from atoms that are in the semiconductor material as light strikes the solar cell. An electrical circuit is hooked up to both sides of the cell, forming an electric circuit. When a number of these solar cells are attached together, they form a solar array. This can also be called a photovoltaic module. These modules are designed to supply electricity at a certain voltage. When these modules are wired together, they form an array. These Photovoltaic modules and arrays produce Direct Current (DC) electricity. By hooking these modules in series, you can produce any voltage you want. By hooking them in parallel, you can create as much current as you like.
The most common type of photovoltaic devices, use a single junction within the semiconductor. This is called a single-junction PV cell. There is a great limitation with this technology. With a single junction PV cell, only photons whose energy is equal or greater than the band gap of the cell material can free electrons for the electric circuit. By using multi-junction cells (those that have more than one band gap to generate voltage), you get a lot higher conversion efficiency, since they can convert more of the light spectrum into electricity. In the multi-junction cell, one or all of the cells contain gallium arsenide, which is about 35% efficient under concentrated sunlight.
As technology continues to improve, more of the abundance of solar energy will be captured and put to use.