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The Basics of Solar Power

Solar cells absorb sunlight and convert it to electricity. This is known as the photovoltaic (PV) effect. Solar, or PV, cells are most commonly made from crystalline silicon.

Each cell is a wafer thin disc that has been subjected to a process called doping. Minute amounts of phosphorous are added to form the very thin upper layer and minute amounts of boron are added to form the somewhat thicker lower layer.

This process turns the silicon from an insulator into a semi-conductor and leaves the cell in a state of electrical equilibrium. That is, until the vital ingredient, sunlight is introduced.

Metallic electrical contacts and an anti-reflective coating are added to the front surface of the cell and an aluminized conductive material is placed on the back surface of the cell. Wiring completes the circuit. 

When photons of sunlight strike the cell, electrons are released. They are moved through the silicon and are picked up by the electrical contacts. They move into the external circuit in the form of direct current (DC) - the type of electrical current in a regular battery. The power flows through the load (for example, a light bulb) and back into the solar cell on the lower side, completing the circuit.

   

The entire process is self-contained. There are no moving parts and no materials are used up or given off.

The solar or photovoltaic cell is the basic component of your solar electric system. Each cell alone produces only a small amount of electricity.

Solar cells are connected together and encased in a protective shell behind a sheet of glass to form a module or solar panel. Each panel has a metal frame and is equipped with connectors and can be transported and installed safely and easily.

Your solar electric system comprises a number of modules or panels that are variously arranged into a solar array. The particular configuration chosen will determine the amount of electricity your system produces.

Layers of the Solar Panel

A. Glass Cover Plate: The cover plate is used to protect the cells from the elements. This should be kept clean in order to achieve maximum efficiency.
B. Antireflective coating: Silicon is a highly reflective material so an antireflective coating is used to reduce the losses due to reflection.
C. Contact Grid: The electricity generated by the silicon needs to be able to flow to the terminals. To help with this a grid of wire is placed on top of the silicon so that the electricity can flow through the low resistance wire instead of the silicon. A grid must be used so that most of the silicon is left exposed to the light.
D. Silicon Layers: Silicon is a semiconductor material that is used to convert energy from the sun into electricity that can be used to power our homes. The silicon is the part of the solar cell that does the work. There are two layers of silicon, each of which have slightly different properties in order to generate electricity.
E. As for D.
F. Bottom Contact: This layer works the same as the contact grid that is placed above the silicon layers. It is used to help the electricity flow to the terminals. Since the bottom of the silicon not have to be exposed to the light, the bottom contact can cover the entire surface of the silicon.
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