In 1921, Albert Einstein won the Nobel Prize for physics. Belated recognition for the researcher’s two theories of relativity, from which the iconic E=mc2 was formulated sixteen years before? In fact, the Swedish academy was actually recognising his work on the nature of light and an explanation of the photoelectric phenomenon.
In his work, the physicist explained the hypothesis that light could travel not just in wave form but also in energy packets—grains of energy that were soon renamed photons. Putting it simply, when exposed to light or another form of high-frequency electromagnetic radiation, a metal spontaneously gives off electrons. This theoretical explanation would have a number of applications, starting with camera photocells, detectors for automatic doors, and solar panels, paving the way for the photovoltaic effect.
On 25 April, three American researchers, Pearson, Chapin and Fuller, from Bell Laboratories, gave a public demonstration of an efficient silicon photovoltaic cell, which could convert 6% of the sun’s energy into electricity. Its yield was six times higher than previous prototypes, which could only power a small radio or a toy.
The breakthrough came by designing a silicon sandwich, with the first layer treated with arsenic to give it a negative charge and the second layer given a positive charge by boron salts, with both layers coated in matte plastic to absorb light instead of reflecting it. The modern solar cell was born. Four years later, they would power one of the two transmitters of Vanguard I, the second American satellite to be successfully launched.
Using the world’s most abundant source of energy (the sun), solar and photovoltaic panels currently account for 0.4% of the planet’s power supply, and 4% of its electricity. This under-use of the potential is clearly due to the fact that the source is intermittent: subject to the vagaries of the weather, photovoltaic panels cannot as yet generate electricity when the sky is cloudy or when night falls.
Hence the need to overcome two technical challenges – improving solar panel yield in order to generate more power in less time on the one hand, and finding cheap energy storage solutions on the other. Some researchers are already working to overcome these challenges, pointing out the hopes raised by graphene as a way to make solar cells ten times more efficient, and the ability to collect infrared rays from the Earth, allowing photovoltaic panels to work at night!
50 cents per peak watt, that is the current average cost of generating energy from photovoltaic cells. In the 1960s, when the space industry was fitting them to its satellites, the price was around €1500 per peak watt (Wp). A decade later, it had dropped to $50 following a new technological leap forward. 45 years later, the cost is a hundred times less, due mainly to a series of technological breakthroughs at the beginning of the 21st century: a finer layer of silicon, using plastic instead of glass, increased automation in manufacturing techniques, and soon, a new method of heating silicon plates…
Since January and the invitation to tender that was won by a Saudi company—ACWA—to build a solar power plant in Dubai to generate a current for 6 cents per kilowatt-hour, solar energy has the luxury of being cheaper than energy from coal-fired power plants. The time of renewable energy is drawing near.
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Ever closer to the sun