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Encyclopedia of Electrical Engineering
HOME Q & A TABLE OF CONTENTS
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Encyclopedia of Electrical Engineering
HOME Q & A TABLE OF CONTENTS

Solar Cell

What is Solar Cell?

Solar cells, sometimes called photovoltaic cells, convert energy from the sun directly into electricity. Solar cells produce renewable energy, and are durable, portable and low-maintenance. Unlike batteries or fuel cells, solar cells do not utilize chemical reactions or require fuel to produce electric power, and, unlike electric generators, they do not have any moving parts.
Fig.No.1: Single Solar cell.
Solar cells can be arranged into large groupings called arrays. These arrays, composed of many thousands of individual cells, can function as central electric power stations, converting sunlight into electrical energy for distribution to industrial, commercial, and residential users. Solar cells in much smaller configurations, commonly referred to as solar cell panels or simply solar panels, have been installed by homeowners on their rooftops to replace or augment their conventional electric supply.
Introduced in the 1950s, their first use was for communications satellites, and they continue to provide power for many space-based applications. On earth, Solar cells also produce energy in remote settings, powering equipment far from the nearest electrical outlet.

How Do Solar Panels Work?

Solar panels work by absorbing sunlight with photovoltaic cells, generating direct current (DC) energy and then converting it to usable alternating current (AC) energy with the help of inverter technology.
Fig.No.2: Residential Solar panels.
A standard solar panel consists of a layer of silicon cells, a metal frame, a glass casing and various wiring to allow current to flow from the silicon cells. Silicon is a nonmetal with conductive properties that allow it to absorb and convert sunlight into electricity. When light interacts with a silicon cell, it causes electrons to be set into motion, which initiates a flow of electric current. This is known as the photovoltaic effect, and it describes the general functionality of solar panel technology.

Off-Grid Power

In addition to producing electrical power for the commercial grid, solar cells see wide use as an off-grid energy source. For example, many traffic, emergency and construction road signs use solar cells for power, reducing the need for gasoline-powered generators for remote and mobile uses.

Rooftop Solar Panels

Many commercial and residential buildings have solar panels that produce electricity; in most cases, the building gets its power primarily from a conventional utility connection, but the solar cells generate enough power to reduce the owner's conventional electric use and the associated electric bill. The solar panel connects to a power management system that automatically switches to the utility when solar power isn't available.

Satellites

Communications satellites require an electric power source that is lightweight, lasts for years, and works in the vacuum of space. Because solar energy is abundant above the earth's atmosphere, photovoltaic cells have proved an ideal solution for powering satellites. They generate electricity continually without the need for battery replacements or fuel; this is a nearly-absolute requirement for satellites, as their maintenance is impractical and prohibitively expensive.