Enough sunlight falls on the earth’s surface every hour to meet world energy demand for an entire year. This sunlight can be converted into electricity through a method known as the photovoltaic (PV) effect.
Solar panel history
Although solar technology was used as far back as 7th century BC and there are records of ancient Romans utilizing the sun to warm their houses in the 6th century AD, nineteen-year old French physicist Alexandre Edmund Becquerel is credited with discovering the photovoltaic effect in 1839 while experimenting with a solid electrode in an electrolyte solution. Silver chloride was placed in an acidic solution and illuminated while connected to platinum electrodes. During the experiment, Becquerel found that certain materials would produce small amounts of electric current when exposed to light. The word “photovoltaic” was formed by combining light (photons) and electricity (voltage).
How do solar photovoltaic panels work?
The basic unit of a solar photovoltaic panel is a solar cell (aka PV cell). Each photovoltaic cell is made up of at least two layers of semi-conducting material, usually silicon, one of the most common elements on earth. Boron is added to one layer of silicone, resulting in fewer electrons and a positive charge, while the other layer is dosed with phosphorous, which adds extra electrons creating a negative charge. These positive and negative layers create an electric field.
Sunlight is composed of packets of energy called photons. These photons contain various amounts of energy corresponding to various wavelengths of light. When photons strike a solar cell, they may be reflected, absorbed, or pass right through. When enough photons are absorbed by the negative layer of the solar cell, electrons are knocked loose from the atoms in the negative semiconductor material. These freed electrons naturally migrate to the positive layer creating a voltage differential.
If electrical conductors are attached to the positive and negative sides, forming an electrical circuit, the electrons can be captured in the form of an electric current, forming electricity. Since the electricity generated by solar cells is direct current (DC), it is then sent to an inverter that converts the power into the same alternating current (AC) used by the appliances in your home and the local distribution grid.
Each individual solar energy photovoltaic cell produces only 1-2 watts. To increase power output, photovoltaic cells are electrically connected to each other and mounted in a weather-tight support structure called a solar module. These modules are then wired up in serial and/or parallel with one another into a solar array to generate the desired voltage and amperage output required to meet the business or home’s energy needs.
Solar power can be used to lower your electric bill or, with battery backup, even enable you to get off the electric grid and not have to depend on the utility company. The size of the solar photovoltaic array, inverter, and battery required for a PV installation depends on a number of factors, including the amount of electricity you use, the amount of sunlight received, and peak electricity demand at any given time. Contact one of our friendly associates at Haleakala Solar to determine the right photovoltaic system for you.