How Do Tandem Solar Cells Work?

[Music] you've probably seen solar cells on the rooftops of houses as of today almost all of these are based on single junction solar cells which are limited in how efficient they can get that is in how much of the sun's energy they can successfully convert into electricity tandem solar cells get past these limits to produce more power per unit area these are likely the future of solar energy harvesting a single junction solar cell has a single semiconductor material that absorbs light let's take a moment to understand how a semiconductor absorbs light semiconductors have ranges of energy that the electrons in them can have these are called bands the gap between the lower band which is full of electrons and the upper one which is empty is called the band gap light is absorbed when an electron takes the energy of a photon of light and jumps up across the span gap but if the energy of the light is smaller than the band gap the light simply passes through without being absorbed light whose energy is larger than the band gap is absorbed but the excess energy beyond the band gap is quickly lost as heat and cannot be harvested these two losses mean that single junction solar cells always waste quite a bit of the energy that they get from sunlight the way to get around this limit is to combine solar cells with different band gaps that complement each other and stack them one on top of the other the first cell has a large band gap and absorbs the high energy light it does not waste much of this energy but it also fails to absorb low energy light which just passes through but the second cell has a small band gap and absorbs the low energy light which the first cell allowed through you get the benefit of not throwing away energy from the high energy light but you also absorb the low energy light this way tandem solar cells where two sub-cells with different absorber materials complement each other and work in tandem get past limitations on single junction solar cells and reach high efficiency you

Channel: Swift Solar

Views: 6,326

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Id: VbFdPcFZViE

Length: 2min 56sec (176 seconds)

Published: Thu Jan 06 2022