How Does Solar Technology Actually Work?
Solar technology works on the simple principle of Photovoltaic effect. Sunlight contains photons. When they fall on a semiconductor like Silicon, the solar radiation frees electrons of the semiconductor. This creates an electric field which in turn produces electricity. Light's use for electricity was first applied when Bell Labs invented the Photovoltaic (PV) cell in 1954.
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Solar technology uses sunlight (solar) and heat (thermal) energies of the Sun. We will discuss the mechanism behind each.
How Do Solar Panels Work?
Solar power today fuels satellites, calculators, homes, and entire buildings. A solar panel harnesses solar energy, and each panel contains 36-72 PV cells. They are encased in a metal panel and tacked inside a protective glass case. A wire runs around the panel. DC current is produced via the photovoltaic effect. The wire collects the DC current and sends it to the inverter. The inverter converts the DC into AC current. It is then used to run electrical appliances.
You can mount solar panels on rooftops for commercial or residential use. You can also find lines of solar panel stacked on acres of soil for high electricity production. This is called solar farming.
How Does Thermal Solar Energy Work?
We use sunlight's heating properties to generate electricity too. There are two types thermal power generation: active or passive.
In active thermal power generation, sun's rays are concentrated on a single source. A heat exchanger fluid like ethylene glycol is heated until converting it into high-pressured steam. The steam makes the turbine rotate. Generators convert this mechanical energy (movement of steam) into electricity. Parabolic Troughs, Parabolic Dishes, and Solar Towers use this concept.
Active Thermal power is even used in solar water heaters. Here, water is fed to a cylinder which transfers the water into a set of evacuation tubes -- copper pipes with a coat of black paint -- to heat the water and a fluid, typically glycol. Due to the differences of densities of cold and hot water, the latter rises back into the cylinder while the cold water takes its place in the tubes and the process continues. The warm water is transferred to your water tank at home. The fluid glycol gets heated and circulates throughout the system, preventing the water from freezing.
Unfortunately, during cloudy days or night-time, the heater may not work efficiently. But the cylinder, which stores the warm water, has thick insulation. It keeps the water warm for long periods.
Passive Thermal Power is typically seen in homes or greenhouses. No complicated set up needed here. Windows allow sunlight inside houses and warm ceramic tiles or bricks (known as thermal mass) as they absorb heat. Heat is distributed and regulated through processes of conduction, radiation, and convection.
Light is an ancient form of energy (appx. 13.7 bn years old). But only less than 200 years ago did we learn to find its use in electricity. Such a mysterious force!
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