The History of Solar Power
Solar energy has been used in various ways since the 7th century BC when the sun’s rays were magnified and used to create fire. In the third century B.C. the Greeks and Romans used ‘burning mirrors’ to light torches for religious purposes. It has been said that in the 2nd century B.C. Archimedes used the reflective properties of brass to set fire to Roman ships attacking Syracuse. By the 6th century A.D. sunrooms on houses were so popular that the Justinian Code initiated ‘sun rights’ to ensure individual access to the sun.
All early uses of the suns energy focused on heat and passive solar design. Passive solar covers everything from where to position your doors and windows to gain the most heat in buildings, to warming items that hold their heat through the night. Click here for example and information on an indirect gain tromble wall design that uses passive solar.
The first solar cell
The world’s first ‘solar collector cell’ is commonly considered to have been conceived and constructed in 1767 by a Swiss scientist called Horace-Benedict de Saussure (right) when heat power, mainly steam, was being explored. He constructed an insulated box with an opening and three layers of glass. It magnified the suns heat to temperatures in excess of 230 degrees Fahrenheit and could be used in a variety of ways.
The photovoltaic effect
In 1839 we encountered a major milestone in the evolution of solar energy: The defining of the photovoltaic effect. At the age of 19 a young French scientist by the name of Edmund Bacquerel discovered the photovoltaic effect whilst experimenting in his father’s laboratory with an electrolytic cell made up of two metal electrodes placed in an electrolyte. After exposing it to light, electricity increased. Willoughby Smith first described the “Effect of Light on Selenium during the passage of Electric Current” in an article that was first published in the February 1873 issue of Nature. It was six years before the first solid state photovoltaic cell was manufactured by Charles Fritts, who coated the semiconductor selenium with a thin layer of gold to form the junctions. This device was only around 1% efficient but was the first to demonstrate that solid material with no moving parts could be used to convert sunlight directly into electrical energy.
The persuit of the increase to photovoltaic efficiency
Since the above discovery, scientists main goal has been to increase the efficiency of photovoltaic cells. Starting in 1888 with a Russian physicist called Aleksandr Stoletov (left) who built the first photoelectric cell based on the outer photoelectric effect discovered by Heinrich Hertz earlier in 1887 (in the Photoelectric effect, electrons are emitted from solids, liquids or gases when they absorb energy from light). The discovery that ultraviolet rays can cause a spark to jump between two electrodes led to the creation of the solar heater unit in 1891.
Albert Einstein published a paper on this photoelectric effect and the underlying mechanism of light instigated carrier excitation in 1905 for which he won the Nobel Prise in physics in 1921. Possibly in response to Einstein’s paper, William J. Bailey invented the Copper Collector in 1908 which improved the efficiency of the original done collector method simply by using copper insulation. The improvements achieved by this method are still being used in today’s equipment. It was, however, Russell Ohl that patented the modern junction semiconductor solar cell in 1946.
Solar panels in the modern era
By the year 1953 the study of Global Warming was hitting the press, both Time magazine and Popular Mechanics ran articles on the subject. People were starting to become aware of the depletion of fossil fuels and the need for a more renewable energy source. The first practical photovoltaic cell was developed in 1954 at Bell Laboratories by Daryl Chaplin, Gerald Pearson and Calvin Souther Fuller. A couple of years later and the U.S Signal Corps Laboratories were developing photovoltaic cells for Earth orbiting satellites which led to the solar array on the Vanguard 1 space mission. With further developments solar power became the accepted energy source for space application and remains so today.
The commercialisation of solar power
A company called Hoffman Electronics managed to increase the technology’s efficiency to 14% leading to various attempts to commercialise solar photovoltaics in the 1950s and 60s, with little success. The price of achieving a watt of electricity dropped considerably in the 1970s leading to the unit’s application in remote locations where grid connected utilities could not exist affordably.
By 1980 solar panel power plants were being built with ARCO solar producing more than 1 megawatt of photovoltaic modules a year. The company helped set up the first megawatt-scale power station in Hisperia, California. Later that year construction on a U.S. Department of Energy project named Solar One was completed. Solar One produced 10 megawatt of electricity by concentrating the sun’s energy into a common focal point to produce, heat to run a steam turbine generator. It did so using 1818 mirrors, each 40m2 (430 ft2) with a total area of 72,650 m2. By 1985 sales of photovoltaic cells had reached $250,000,000 and the University of South Wales had increased the efficiency for silicone solar cells to 20% under 1-sun conditions. A year later ARCO release the first commercially available thin-film solar power module.
In 1994 The National Renewable Energy Laboratory in America developed a solar cell made from gallium indium phosphide and gallium arsenide that breaks the 30% efficient mark meaning that it converts 30% of the sun’s light that strikes it into usable electricity. A skyscraper in New York City (right) incorporated these new higher efficiency thin cells on a selection of its floors to help meet the buildings energy needs a few years later.
By the year 2000 construction of solar panels at the largest photovoltaic manufacturing plant reached an estimated capacity of producing 100 megawatts of power a year. Solar power had become big business for manufacturers and sellers the world over. People worldwide, especially those in leadership roles were becoming increasingly aware of the need to lower our dependence on fossil fuels and develop more eco-friendly means of powering our lives. Scientific endeavour in the renewable energy industry was increasing exponentially and solar power was the flagship technology.
Domestic solar panel implementation
At the turn of the century, large domestic and commercial solar initiatives were in play. In 2004, Governor Arnold Schwarzenegger proposed a scheme for 1 million solar roofs in the state of California. Germany along with a few other nations had developed a highly successful domestic solar photovoltaic market. By 2006, widespread news coverage of several major high street electrical retailers’ decision to stock solar PV modules and offer an install service started the ball rolling here in the UK. Now we are all familiar with solar photovoltaic arrays which we can see on the roofs of the buildings around us. At the end of 2011 there were 230,000 solar power projects in the United Kingdom. The UK government has said that 4 million homes across the country will be fully or partially powered by the sun within eight years. This is all thanks to technological developments and the fact that we have an insolation level (short for incident or incoming solar radiation) similar to that of Germany which is, and has been by far the biggest market for domestic photovoltaics, with currently more than one third capacity installed. Nonetheless, solar energy remains an underexploited resource in the United Kingdom, which continues to derive the majority of its energy from increasingly expensive and environmentally harmful fossil fuels such as gas and coal.
Utility scale solar power generation
In the past years we have seen enormous investment in utility-scale solar power plants, with records for the largest frequently being broken. Currently the largest solar energy plant is the Golmud Solar Energy plant in China, with an installed capacity of 200 megawatts. However, a solar project in India called Gujarat Solar Park, which is comprised of a collection of separate solar farms boast a combined installed capacity of 605 megawatts.