The fastest energy transition in history is not the industrial revolution, as many think, but the one that is happening now With renewable energies. Renewables are being installed at a rate five times greater than all other combined energy sources. And although the great habilitator is the worldwide commitment to zero net emissions, it is the brutal evolution of solar panels that has allowed to reach this point.
Photovoltaic panels have been so much that solar energy Start leaving wind energytraditionally more efficient. Throughout the last decades, solar cells have experienced a radical transformation, driven both by advances in material engineering and in innovations in manufacturing techniques; mainly from the Chinese industry, although Japan is trying to lead The next generation.
The National Renewable Energies Laboratory (NREL) has Published a graph that illustrates at a glance How each photovoltaic technology has advanced since the 70s and which cells are more efficient today.
Traditional cells: crystalline silicon
Crystalline silicon cells
The crystalline solar cells of silicon (blue in the graph) have dominating the market for several decades. The polyristaline silicon (the one used in solar panels with bluish crystals) is cheaper, but monochronic silicon (with black crystals) is the current standard of the industry thanks to continuous improvements in purification and production processes, which have approached their efficiency to an ability to convert 27.6% of sunlight into energy.
Thin film technologies (green in the graph) emerged as an alternative to the crystalline silicon for facilities that require greater flexibility, lower weight or a large -scale manufacturing. The most efficient thin film cells are currently those of copper, Indian, Gallic and Selenium (CIGS) with an efficiency of 23.6%, closely followed by those of cadmium teluro (CDTE).
The emerging: organic and perovskitas
Emerging technologies cells
Red in the graph, they are the photovoltaic cells that have tried to remove the throne from the silicon. Organic cells and coloring sensitized cells (DSSC) use organic compounds to absorb light. Its efficiency is modest (around 19%), but they have the advantage of their low cost and the possibility of integrating them into flexible devices and buildings with varied colors.
One of the most revolutionary innovations in recent years has been the development of Perovskita cells (red with yellow filling in the graph). Thanks to its crystalline structure inspired by the mineral of the same name, these cells have been achieving exponential increases in efficiency in a short time, even if they were invented in Japan in the 80s. Perovskita cells are already as efficient as silicon, with an efficiency of 27%, but they have the problem of degrading much earlier.
The tandem, the best of both worlds
Tandem two materials cells
The photovoltaic cells that make up silicon and perovskita in tandem are the most promising for generalized use today. The secret of combining both materials is that the upper perovskita layer absorbs high -energy wavelengths and the lower silicon layer captures the rest of the spectrum.
With an efficiency of 36.1%, Tandem cells (brown in the graph) have left behind the theoretical limit of traditional silicon cells (33.7%). Although in the laboratories we still try to look for alternatives to the silicon, which is a more expensive material and with a supply chain controlled by China.
All photovoltaic cells and their evolution
By the latter, triple or more layers (multijunction) unions are the cells that have reached the greatest efficiencies in laboratory conditions: up to 47.6%. Its cost is high and its production is complex, but these cells are useful in solar concentrators, where maximum performance is sought.
Images | NREL
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