subject: Multijunction Solar Cells - Technology Imitates Nature [print this page] It's Been Around Longer Than You Think It's Been Around Longer Than You Think
The idea of generating electricity using sunlight dates back almost to the time people started using electricity. In fact, a photovoltaic effect was first produced around 1840 - not long after Queen Victoria ascended to the British throne. However, it was another fifty years or so before someone actually created a working solar cell, and another twelve years before Einstein was able to explain how it worked (he won the 1921 Nobel Prize for that). The first modern multijunction solar were made just after World War II.
In simple terms, a solar produces electricity when sunlight (photons) hit the surface. This sunlight is absorbed by a semi-conductor, usually silicon. This causes electrons, the subatomic particles that carry a negative electrical charge, to come loose from the atom, which ultimately produces electrical current.
The Problem - and Solutions
The problem with those silicon flat-panel solar arrays is that they aren't terribly efficient. However, a cpv solar cell array can have an efficiency rate of over 40%, meaning that two-fifths of the light that hits the surface is converted into electrical current. This figure is going up, and within the next year or so, a cpv solar cell array will have what is called grid parity with today's fossil-fueled power plants, meaning that a grid of solar cells will produce the same amount of energy as an equivalent fossil fuel setup.
The secret is that new solar cells have multiple layers, each of which captures a different part of the light spectrum. As you probably know, sunlight contains several different colors, which we cannot perceive until that sunlight is broken up into its components by a prism, such as a crystal or water droplets. You see the different parts of the spectrum when a rainbow forms in the sky after a rainstorm.
Multijunction Solar Cells - Technology Imitates Nature
