We often think of solar power as a modern form of technology, but using the sun to generate energy dates back at least to the middle of the 19th century. At the height of the Industrial Revolution, engineers developed different types of solar plants which heated up water, creating the steam necessary to drive machinery in factories.
These early solar power plants fell by the wayside somewhat, as compared to coal-fired steam turbines, their output was small and unreliable, especially on cloudy days and at night.
The history of solar panels
1839: Alexandre Becquerel observes the photovoltaic effect using an electrode placed in a conductive solution and then exposed to light.
1873: Willoughby Smith finds that the metal selenium displays photoconductivity.
1883: Charles Fritts develops a solar cell composed of selenium on a thin layer of gold; this cell offers less than 1% efficiency.
1887: Heinrich Hertz studies UV light photoconductivity and discovers the photoelectric effect PE.
1888: Edward Weston receives the patents US389124, “Solar cell,” and US389125, “Solar cell.”
1888-91: Aleksandr Stoletov creates the world’s first solar cell based on the outer photoelectric effect.
1905: Albert Einstein publishes his paper explaining the PE effect on the quantum level.
1918: Jan Czochralski develops a method to grow single crystals of metal. This method is later adapted to produce single-crystal silicon.
1921: Einstein receives the Nobel Prize in Physics for his work on PE.
1941: Russell Ohl files the patent US2402662, “Light sensitive device.”
1950s: Bell Labs make solar cells for space-related work.
1954: Bell Labs announces the invention of the first practical silicon solar cell, which has an efficiency of around 6%.
1959: Hoffman Electronics creates a commercial solar cell with an efficiency of 10%. This high efficiency is due to a grid contact, which reduces the cell’s resistance.
1960: Hoffman Electronics produces a 14% efficient cell.
1974: The Florida Solar Energy Center starts out.
1974: J. Baldwin, at Integrated Living Systems, helps to develop the world’s first building – in New Mexico – that was solely heated and powered by solar and wind power.
1977: The world’s PV cells exceeded 500 kW in output.
1978: The world had its first solar-powered calculators.
Late 1970s: The “Energy Crisis” stimulates interest in solar power around the world.
1983: Worldwide PV production exceeds 21.3MW, and sales top US$250 million.
1985: The Centre for Photovoltaic Engineering at the University of New South Wales creates 20% efficient cells.
1991: Efficient photoelectrochemical cells are developed in Switzerland.
1991: US President George H. W. Bush establishes the National Renewable Energy Laboratory.
1999: The total worldwide installed PV power reaches 1,000MW.
2003: US President George Bush has a 9kW PV system and a solar thermal system installed in the White House’s groundskeeping building.
2006: A newly-developed solar cell breaks the 40% efficiency barrier.
2008: The US Department of Energy’s National Renewable Energy Laboratory develops a cell that converts 40.8% of the sunlight hitting it into electricity. This amazing efficiency needed the concentrated power of “326 suns”, however.
2010: US President Barack Obama ordered more solar panels and a solar water heater for the White House; these are installed in 2013.
2011: Chinese manufacturers push down the price-per-Watt of silicon PV modules to US$1.25 and worldwide installations double.
2016: Engineers at the University of New South Wales establish a new world record for unconcentrated sunlight conversion – 34.5%.
2018: US-based Alta Devices produces a gallium arsenide PV cell capable of an efficiency of 29.1%.
How solar panels convert sunlight to electricity
When photons hit certain compounds, they cause electrons to “jump” out and other compounds “take in” electrons. These different compounds, used in conjunction, cause electrons to flow through a conductor, creating an electrical current. This flow is the photoelectric, or PV, effect.
Solar panels are good for the planet
Once in use, a solar panel will generate electricity without causing any pollution or waste. As panels have no moving parts, they’re very reliable – some can last for decades. They’re also very easy to retrofit and don’t need much maintenance going forward.
Another handy aspect to PV panels is that you can have as few or as many as you like. This is in contrast to the huge coal or gas-fired power stations which have to be of a certain size to power a city or region.
