Solar Energy uses the sun`s rays as a source of clean, renewable electricity. It`s also a way to reduce the amount of carbon dioxide that enters the atmosphere.
But, solar power`s growth has not been without its challenges. The industry is facing shortages of the materials that make up photovoltaic cells, which in turn can drive up prices.
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Photovoltaics
Photovoltaics (or PV) use the sun`s energy as a source of electricity. This is done by converting sunlight to electricity directly, using semiconducting materials such as silicon.
Solar cells, or PV modules, are grouped together electrically and used to make a solar panel. Each cell is small and can produce around 1 to 2 watts of electricity.
The cells are made of different semiconductor materials. These materials conduct electricity more efficiently than insulators, but less efficiently than metals.
When light hits a solar cell, it knocks electrons loose from the atoms in the semiconductor material. This creates a voltage potential that is similar to the negative and positive terminals of a batteries.
Most modern solar cells are based on crystalline silicon, but other technologies use thin-film materials such as amorphous silicon and copper indium gallium selenide (CIGS). A new class of multi-junction or tandem cells is also under development that can convert sunlight into energy at very high efficiencies.
Concentrating solar power
Concentrated solar power (CSP), a relatively new form, uses a special mirror to focus the sun`s rays. The rays heat up fluid, which turns turbines to generate electricity.
CSP plants are capable of producing up to 1,815 megawatts in power in the United States today. They aren`t necessarily the most reliable or efficient form of solar power.
To produce CSP power, a field of specialized mirrors is deployed to reflect sunlight onto a central receiver, which contains a store of molten salt or thermal oil. The heat transfer fluid is then piped into a generating station, where it turns turbines to produce electricity.
Solar thermal
Solar thermal technology makes use of the sun`s heat to produce low-cost and environmentally friendly heat. This can be used to heat water for use in your home, cook food, or generate electricity.
The first type of solar thermal power plant is the parabolic trough, which relies on mirror-faced reflective collectors to concentrate sunlight onto tubes filled with a heat-transfer fluid (like antifreeze, water or synthetic oil). The hot liquid then cycles through a heat exchanger where it is turned into steam and runs a turbine, which powers a generator to produce electricity.
Another type of solar thermal power plant is the power tower, which is a large system able to concentrate the sun`s energy as much as 1,500 times. It uses thousands of heliostats, which are large flat sun-tracking mirrors, to focus the sun`s radiation onto a single tower-mounted receiver.
Solar hot water
Solar hot water systems heat your water, making it possible to use it whenever and wherever you like without having to turn on any external sources. These systems are cost-effective and can be financed with federal tax credits, or other incentives available in some states.
There are two main types of solar hot water systems: passive and active. Passive systems rely on gravity to move fluid and water throughout the system, while active solar hot water systems have a controller that pumps antifreeze fluid or water from a collector to the tank.
There are many different types of solar hot water systems, and each one has its own benefits and drawbacks. It is important to select the best system for your home.