Solar Energy

Our sun is a natural nuclear reactor. It releases tiny packets of energy called photons, which travel the 93 million miles from the sun to Earth in about 8.5 minutes. Solar energy is the technology used to harness the sun's energy and make it useable. A solar cell is a device that converts light directly into electricity using the photoelectric effect.

When photons hit a solar cell, they knock electrons loose from their atoms. If conductors are attached to the positive and negative sides of a cell, it forms an electrical circuit. When electrons flow through such a circuit, they generate electricity. Multiple cells make up a solar panel, and multiple panels (modules) can be wired together to form a solar array. The more panels you can deploy, the more energy you can expect to generate.

Photovoltaic (PV) solar panels are made up of many solar cells. Solar cells are made of silicon, like semiconductors. They are constructed with a positive layer and a negative layer, which together create an electric field, just like in a battery. PV solar panels generate direct current (DC) electricity. With DC electricity, electrons flow in one direction around a circuit.

In traditional solar modules (polycrystalline and monocrystalline), silicon wafers are impregnated with impurities to create a semiconductor that converts sunlight into electric current. Electrical contacts are then created to join one solar cell to another. As silicon reflects, an anti-reflective coating is placed on top of the silicon wafers, usually titanium dioxide or silicon oxide.

The solar cells are laid between a superstrate layer on the top and a backsheet layer on the bottom. The superstrate is usually glass, and the backsheet is plastic. This is then placed inside an aluminium frame to create a finished solar panel.

A solar inverter takes the DC electricity from the solar array and uses that to create AC electricity. Inverters are like the brains of the system. Along with inverting DC to AC power, they also provide ground fault protection and system stats, including voltage and current on AC and DC circuits, energy production and maximum power point tracking.

 How a home solar energy installation works? First, sunlight hits a solar panel on the roof. The panels convert the energy to DC current, which flows to an inverter. The inverter converts the electricity from DC to AC, which you can then use to power your home. It’s beautifully simple and clean, and it’s getting more efficient and affordable all the time.

The history of Science and technology

The development of Science and technology is as old as mankind. Many ‘inventions’ claimed after the 11th century in fact dated back to the Greeks and Chinese many centuries before. Scientific information proposed by the Greek philosopher Aristotle (384 – 322 BC) and others was lost in the Dark Ages in Britain and Europe after the collapse of the Roman Empire.

The birth of technology (2 million years BC)

Tools

The birth of ‘technology’ was when the first human-like species, Homo habilis (‘skilful person’ 2.6 million years BC) made sharp cutting edges from stone. Later, Homo neanderthalis or cave men (200 000 – 30 000 years BC) used tools and weapons and were the very successful ancestors of Homo sapiens, the species we recognise as our ancestors today.

Metals

 Lead (Pb), one of the softest metals, was being extracted from rock in 6500 BC in Anatolia (now Turkey) followed by copper (Cu) three thousand years later in Mesopotamia. The Iron Age was built on a hard, strong and versatile metal, iron (Fe).

 The wheel

Around 4500 BC the wheel and axle combination became the most important invention of all time. Carts came into common use. By 2000 BC wheels had spokes, and then rapid development occurred with waterwheels and windmills to provide power.

New inventions (9th – 18th century)

 Arab alchemy

Turning common metals into precious metals, proved to be a dead end around the 9th century AD. Nevertheless, Arabs were clever chemists and discovered many chemicals that we use today. Gunpowder

The recipe for making gunpowder appeared in a book in Europe in 1242. Roger Bacon (1214 – 1294), an English  friar and philosopher, was the first to describe its formula. Guns soon followed.

 Printing

Spreading knowledge and information was a very slow process before the invention of typography. Johannes Gutenberg (1398 – 1468) developed the first mechanical printing machine in the 1440s. The first printed book was the Bible in 1456 with a run of 150 copies. Each Bible previously took three years to make by hand.

The telescope

 The telescope was invented by Dutchman Hans Lippershey (1570 – 1619). In 1610, using his improved design, Galileo Galilei (1564 - 1642) was able to prove that the Earth revolved around the Sun. This confirmed the ideas of the Polish astronomer Nicolaus Copernicus (1473 – 1543) but it angered the Catholic Church who had adopted the idea that the Earth was at the centre of everything.

The microscope

 Looking at small things became possible when a Dutch maker of spectacles, Hans Janssen and his son, put glass lenses together in 1590 to make a primitive microscope. Anton van Leeuwenhoek (1632 – 1723) took this invention a step further in 1676 with a magnification of 270 times and discovered tiny single-celled creatures in pond water. Ultimately, this helped our understanding of microorganisms and disease.

Lightning conductor

 In 1752, Benjamin Franklin (1706 –1790), the American statesman, philosopher and scientist proved that lightning was a form of electricity when he flew a kite in a thunderstorm. Around 1754, Franklin and the Czech scientist, Prokop Diviš (1698 - 1765) independently developed the lighting conductor to protect buildings from being hit and damaged by lighting. and scientist proved that lightning was a form of electricity when he flew a kite in a thunderstorm. Around 1754, Franklin and the Czech scientist, Prokop Diviš (1698 - 1765) independently developed the lighting conductor to protect buildings from being hit and damaged by lighting.

The first Industrial Revolution (1760 – 1840)

Steam power This era saw the development of steam engines to power factory machinery. Heating water in a boiler to make steam to power a vehicle was a major technological advance. James Watt (1736 – 1819) is recognised as the inventor of the steam engine in 1765. Water could be pumped out of mines and industrial processes speeded up. George Stephenson’s (1781 - 1848) Rocket was the first locomotive to pull heavy loads a long distance. This led to the rapid expansion of railways throughout Britain and the world. The combination of iron and steam paved the way for the great Victorian engineering projects of Isambard Kingdom Brunel (1806 - 1859). He designed bridges, tunnels, viaducts and ships.

Photography

In 1826, after years of experiments, the French inventor Joseph Nicéphore Niépce (1765 - 1833), using ‘bitumen of Judea’ spread on a pewter plate and an exposure of eight hours in bright sunlight, produced the first permanent picture. His technique was improved upon by his colleague Louis Daguerre (1787 - 1851) by using compounds of silver, the basis of modern photography.

The second Industrial Revolution (19th century – 1945)

The electric light

 After many refinements, Thomas Edison’s (1847 – 1931) electric light bulbs were the best and by 1879 they would last for hundreds of hours, much longer than any of their rivals. They were also cheap. To sell bulbs, energy was needed, so Edison’s Electric Illumination Company built their own power station in New York. After many decades he successfully persuaded the public to opt for clean, convenient electric light rather than gas lights.

The telephone

 This is an invention that made money. Alexander Graham Bell (1847 – 1922) was the first in the race to patent a machine in 1876 that you could use to talk to someone on the other side of the world. Admittedly, it was initially from one room to another. The message was “Mr. Watson, come here, I want you”. A year later in 1877 he set up his company and demonstrated long distance calls.

The motor car

 Until the 1860s all prototype motor cars were steam driven. German inventor Nicolas Otto (1832 - 1891) created an improved internal combustion engine in 1876 and this is still the way cars work today. In 1885, the first car, the Benz Patent Motorwagen, was developed by Karl Benz (1844 - 1929). It was a long time before cars became common. Petrol, a cleaning fluid, was only available from the chemist. Famous names such as Rolls Royce and Henry Ford developed the technology; Rolls Royce for the rich and Henry Ford for the man in the street.

The movies

It has been only just over one hundred years since the first movie, or film, was shown by the brothers Auguste and Louis Lumière (1862 - 1954 and 1864 - 1948) in 1895 at the Grand Café in Paris. The terrifying film was entitled The Arrival of a Train at Ciotat Station. Surprisingly, the brothers decided that films didn’t have much of a future and went back to photography. In 1889, George Eastman (1854 - 1932) pioneered celluloid film with holes punched in the side so that the movie camera could show the film precisely frame by frame.

X-rays

Science is impressive when something is discovered that cannot be seen. German physicist Wilhelm Rontgen (1845 – 1923) working with electrical discharges in glass tubes noticed in 1895 that there was a faint glow on a nearby screen. These rays were invisible and could pass through most materials. He also recorded them on photographic paper and thus the first X-ray image was developed. He quickly realised the medical potential of his discovery. Henri Becquerel (1852 – 1908) discovered radioactivity in 1896 while trying to find more out about X-rays. Marie Curie (1867 – 1934), a Polish born French chemist and physicist and two times Nobel Prize winner, is best remembered for her research into radioactivity and new radioactive elements.

Communications

 Radio waves travel in all directions at an incredible 300 000 km per second. The German physicist Heinrich Hertz (1857 – 1854) was the first to prove they existed but it was Guglielmo Marconi (1874 – 1937) who set up the world’s first radio stations to transmit and receive Morse code. In 1896, he sent the first message across the Atlantic from Cornwall to Newfoundland. He was awarded the Nobel Prize for Physics in 1909. It was not until 1915 that engineers were able to transmit sound effectively. The first clear television pictures to be transmitted were sent by Scottish-born John Logie Baird (1888 – 1946). He founded the Baird Television Company Limited and worked on programmes for the BBC (British Broadcasting Corporation).

Flight

At the turn of the century, in 1903, two bicycle repairmen from Ohio, Wilbur and Orville Wright (1867 – 1912 and 1871 – 1948) built and flew the first really successful aeroplane near Kitty Hawk, North Carolina. From that time progress was rapid and the military advantages of flight were realised in WWI.

Rockets and space flights

 The earliest rockets were used in China in the 11th century but by the 19th century speed and accuracy were much improved. Knowledge of astronomy meant that scientists knew the relative movements of the planets in relation to the Earth. A Russian mathematics teacher, Konstantin Tsiolkovsky (1857 – 1935), was the first person to draw up plans for space stations and air locks to allow space walks. He correctly calculated that a rocket would have to travel at 8 km per second to leave the atmosphere and that liquid rocket fuel would be essential. American scientist Robert Goddard (1882 – 1945) not knowing of Tsiolkovsky’s ideas independently developed liquid fuelled rockets from 1926. Ultimately, NASA took up the challenge but the Russians eventually won the race to put a man into orbit. Yuri Gagarin (1934 – 1968) orbited the earth in 1961. In the US, NASA scientists redressed the balance in the space race with their moon landing in 1969.

The atomic bomb

Science and technological advances can be seen as good or bad. The invention of gunpowder must have seemed like that. In 1932, physicists John Cockcroft (1897 – 1967) and Earnest Walton (1903 – 1995) did the impossible. They split the atom. They proved Albert Einstein’s (1879 – 1955) theory of relativity (E=mc²) and unlocked the secrets of the atomic nucleus. Splitting the atom was a brilliant scientific achievement. However, having that knowledge allowed scientists to develop the atomic bomb. The use of an atomic bomb on Hiroshima and Nagasaki in Japan to end the WWII in 1945 was a political decision that was highly controversial. We now know that there is no turning back once scientific and technological discoveries have been made.

The third Scientific‑Technical Revolution (1945 - )

After the WWII new discoveries and advances in science and technology came thick and fast. Plastics were developed for the first time. In 1949, the first practical programmed electronic computer ran mathematical problems. It fitted into one room! In the 1960s, the electronic silicon chip was invented; computers became smaller and more powerful. In 1984, the CD was born and the digital revolution began. The worldwide web has given us access to billions of documents with information and images as well as online shopping and banking. Mobile telephone technology means we have instant contact with friends and family. During this period, there have also been huge advances in genetics since the discovery of the structure of DNA in 1953. Today, Biotechnology and genetic engineering show fast growth trends and, also, are big business. It is interesting to wonder what next? Maybe space is the final frontier, as suggested in Star Trek!