The demand for alternative energy sources has skyrocketed in a world with ever-rising energy needs and ever-diminishing nonrenewable energy sources. In contrast to the environmental damages caused by the extraction and burning of dwindling fossil fuels, alternative energy sources promise renewable and often inexhaustible energy with little to no lasting environmental damage. Today, solar power offers one of the greatest opportunities to turn away from inefficient fossil fuel dependence.
The sun has powered the world’s ocean currents, winds, rain, and all the earth’s biomass growth for millenniums. Today, with the growth of modern technology and scientific progress, humans are able to utilize and capture more power from the sun than ever before. There are two significant ways this captured solar power can be utilized: electricity and heat energy.
For both electricity and heat energy, capturing solar power is made possible by employing solar cells in either flat plate receivers that collect incidental solar intensity and can operate in diffuse light, or by means of concentrators that collect higher solar intensities but operate poorly in diffuse light. Flat plate receivers are more commonly known and are often used by homeowners and small businesses. These are the receivers that have cells fixed across a horizontal plane and take the shape of a rectangular prism. A flat plate solar system will respond to radiant energy regardless of cloud cover, but operate overall at a lower intensity than concentrator systems. Concentrators are more commonly used in large energy production, as in town electrical production. These systems operate by focusing parallel beams of light onto a line (parabolic trough) or a point (parabolic dish). Concentrators reduce the amount and size of the cells needed as each cell’s efficiency is improved under concentrated light, but because of this desired concentration they fail to produce energy in heavy cloud cover.
Both these methods utilize solar photovoltaic power (solar) technology, in which the sun’s radiation is directly converted to electricity through solar cell arrays. The word photovoltaic refers to this turning photo (light) into voltaic (electrical current). In PV technology solar cells are constructed of semiconducting materials, and when the cell’s atoms are hit by light they absorb photons which disturb the atom’s electrons. These electrons are then ‘knocked loose’; a friction that creates an electrical current. Importantly, the solar cells are converters, not sources nor storehouses of energy. Also, for every electron knocked loose, another flows back into the cell, making solar cells a constantly renewable energy source. The solar cell acts as a part of a circuit; the electrons travel a continual path, receiving energy from the sun and transferring it to the load before returning to act again as a receiver. The electrical current created by the knocked electrons is transferred to an inverter where it is converted from direct current (DC) electricity to alternating current (AC) electricity. Inverters produce power at desired voltages for appropriate use.