Solar Power Basics

Solar power takes advantage of the photoelectric effect, which is also known by the term photovoltaic. The effect is caused by the interaction between photons of light and the valiance electrons of a metallic surface. To understand how this works, it helps to have a basic understanding of the Bohr model of the atom. In the Bohr model, each atom has several orbital radii at which an electron can exist. These radii are different from the orbital paths of planets in that they are not arbitrary, and they cannot exist just anywhere. In fact, each orbital corresponds to a very specific energy level, and an electron can only exist at those specific energy levels. To move from a near orbital to one further out, an electron must absorb exactly the energy difference between the two.

The electrons have a ground state, which is as close as they can get to the nucleus of the atom they are bound to. When the metal is exposed to light, certain wavelengths will move the electrons into an excited state, which is further from the atom. If light of a high enough energy strikes the metal, it can cause the electrons to break free from the atoms and become unbound. This is the basis of solar power. If a circuit is built on the backside of a thin wafer of a metalloid, the freed electrons are caught by the wiring and can be used to power electric devices.

Solar power creates direct current, which means that the flow of electricity is a straight path in the forward direction. Alternating current, by contrast, actually alternates direction of movement several times a second. This alternation allows AC to be more efficiently transmitted over long distances, which is what led to it being used in our home appliances. Items that are not connected to the home electric grid, such as laptops, flashlights, cell phones, and cars still run on direct current, because DC is easier to transfer to chemical potential energy, or as they are more commonly known, in a battery.

Since solar power creates direct current, it is ideal for powering things like boats or recreational vehicles that have a large draw and are not connected to your home. But to power your lights, or your air conditioning unit, the power must be run through a solar inverter, which changes the DC into AC. This transfer comes at a slight loss of efficiency. This means that if you have both a battery storage system and a connection to the home power, the circuit should go to the batteries before being run into the inverter. Otherwise power that you don’t use immediately is run through the inverter multiple times, causing a drastic drop in efficiency for the system.

Source by Jennifer R Scott

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