What is Solar Power?
The sun supplies energy in the form of radiation. Because of the great distance between the sun and the earth only a tiny part of solar radiation reaches the earth’s surface. In good conditions this equates to approximately 1000 W/m². Of this solar cells can only convert approximately 15% (150W).
How does Solar Power work?
A photovoltaic device (generally called a solar cell) consists of layers of semiconductor materials with different electronic properties. In a typical crystalline silicon cell, the bulk of the material is silicon, doped with a small quantity of boron to give it a positive or p-type character. A thin layer on the front of the cell is doped with phosphorus to give it a negative or n-type character. The interface between these two layers contains an electric field and is called a junction.
Light consists of particles called photons. When light hits the solar cell, some of the photons are absorbed in the silicon. If the photons have enough energy they will be able to free electrons, the electric field at the junction will cause the electrons to move through the silicon atoms in the cell and into an external circuit as electrical current. As they flow through the external circuit they give up their energy as useful work (turning motors, charging batteries, for example) and return to the solar cell.
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