Photovoltaic solar energy is the main variety of system used to generate usable solar power. Understanding the basic system is becoming extremely important as alternative energy sources become a more common and necessary component of daily life. Photovoltaic solar energy can be used to power anything from an outdoor solar lamp to an entire city. Implementing solar energy use into human society is a major part of many government's strategies to move away from unsustainable energy practices and toward an environmentally friendly, sustainable existence.
The sun is an enormous source of energy, burning a convenient 93 million miles (153 million km) from Earth. While the planet receives energy to grow plants through sunlight, converting that light into human-usable power takes some technology. Photovoltaic systems are able to collect sunlight, convert it to energy, and transport it for human use with basic scientific properties.
To create solar energy, a device called a photovoltaic, or PV, cell is required. The PV cell has one surface charged with extra electrons, and a second surface that has positively charged atoms that lack electrons. When sunlight hits a PV cell and is absorbed, the extra electrons become excited, bouncing off the positively charged surface and creating an electrical current where the two surfaced meet. This electrical current is the solar energy that can now be used as power.
PV cells can be arranged together to create power sources of varying sizes. Small arrangements, called modules, can be used to power simple electronics in the same way a battery does. Large groups of PV cells can be used to build solar energy arrays capable of creating enormous amounts of photovoltaic solar energy. Depending on the size of the array and the amount of sunlight, solar energy systems can create enough power to run houses, factories, or even greatly contribute to the energy needs of an urban area.
Many scientists believe that photovoltaic solar energy is of vital importance to human survival. Currently, much of the world is dependent on energy that comes from fossil fuels such as oil and coal. These fuels are made from the decomposition of organisms and can take millions of years to create; humans have overused the available resources so much that many forms of fossil fuels are becoming depleted. Some experts suggest that fossil fuel reserves will begin to run out by the mid-21st century, and will likely completely disappear within a few centuries. In order to keep humanity's energy-run society intact, science must discover ways to power the world with energy that does not come from fossil fuels.
Because solar energy is a renewable resource, it is a vital area of scientific research and development at the dawn of the 21st century. Some suggest that building an enormous photovoltaic solar energy plant in a consistently sunny desert could create enough power to run the whole world, although this does present problems. While a large enough plant could certainly create enough energy, transporting it all over the world is a much trickier proposition. Additionally, as even in the sunniest areas there can be varying rates of sunlight, energy generation from the sun can vary from day to day. By itself, photovoltaic solar energy may not be able to solve the world's energy problems, but in combination with other renewable energy sources such as wind, biofuel algae, hydroelectricity and geothermal power, the days of a fossil fuel-run world may soon be distant memories.