As a source of life, light and warmth, the sun has fascinated humans for thousands of years. Since our species are resourceful by nature, it is no wonder that people have been finding ways to harness its power for centuries.
6 000 BC – 100 BC: Solar architecture.
Some ancient civilisations are known to have utilised the power of the sun through clever architecture. As early as 6 000 BC, Chinese families built their homes with a single, south-facing opening that caught the low winter sun and retained the heat inside.
Image 1: The remnants of an ancient Roman home in Pompeii. The covered porch (portico) naturally controlled the temperature inside the home. Photo: F. Tronchin/Warren, Peristyle, Casa della Venere in Conchiglia, Pompeii, BY-NC-ND 2.0
In the West, the respected Greek philosopher Socrates (470 – 399 BC) advocated the building of homes that faced southward and featured covered porches. These porticoes kept the warm rays at bay in summer, when the sun sits higher, but let the sunlight in during the winter. Socrates’ recommendation came at a time when Greece was experiencing an energy crisis: The price of coal and wood was rising and citizens had to find ways of becoming more energy efficient (which sounds rather familiar today).
The ancient Romans borrowed many ideas from their Greek neighbours and their solar energy solutions were no exception. They, too, applied solar architecture, but took it a step further by covering their windows with transparent materials such as mica or clear glass. They realised that transparent materials trapped the heat from the sun and, today, glass-covered windows are a standard feature of most modern buildings.
The most impressive example of how the ancient Romans used windows to utilise the sun’s power can be seen in their bathhouses. The bathhouses formed the backbone of Roman society and were centres for socialising, networking and relaxing. They were heated through the use of furnaces and hypocaust systems that circulated the hot air. To optimise heat generation and retention, the bathhouses often featured large, south-facing windows. The Baths of Caracalla, for one, featured an impressive south-facing window that spanned the whole wall and was covered in see-through glass. When the sun baked through the expansive window, it effectively turned the room into a sauna.
Circa 1 000 BC – 1500s AD: “Burning” mirrors
Around 3 000 years ago in China, reflective, concave bronze mirrors, called yang-sui, were used to start a fire by focussing the sunlight.
Image 2: An ancient solar device: The Chinese used bronze mirrors as sun-reflecting fire starters. Source: cleantechnica.com
The ancient Greeks and Romans were also known to have used reflective mirrors for lighting torches during religious ceremonies. According to legend, this technology was taken to the extreme by the thinker Archimedes when he constructed his fabled “death ray” in the siege of Syracuse in 212 BC. The “death ray” was created when the Greek soldiers used mirrored shields to turn the sunlight into a devastating blaze when it was deflected towards the invading Roman fleet.
Image 3: Archimedes’ “death ray” depicted by 17th century Italian painter Giulio Parigi. Source: Wikipedia
The idea of using a concave, reflective surface to harness sunlight was further explored by Renaissance luminary Leonardo da Vinci (1452 – 1519). He imagined a water heating system for the city of Florence that comprised a series of concave mirrors that turned the power of the sun into thermal energy.
1767: The Hot Box.
In 1767, Swiss polymath Horace-Bénédict de Saussure conducted a series of experiments to determine how well glass could capture solar heat. He built a glass-topped wooden box that was insulated with black cork and had a similar, but smaller, box placed on the inside. When the box was positioned directly in the sunlight, the temperature inside exceeded the boiling point of water. For obvious reasons, his contraption was dubbed the Hot Box and it paved the way for the thermal collectors we use to heat our homes and water today.
1839: The photovoltaic effect.
Think of solar energy and most of us think of shiny solar panels on rooftops. The solar cells contained within these PV (photovoltaic) panels work on a principle discovered by French physicist Edmond Becquerel. In 1839, he discovered that silver chloride submerged in an acidic solution and connected to platinum electrodes, can generate electricity when it is illuminated.
1896: Hot water.
In 1896, the American inventor Clarence Kemp used Saussure’s Hot Box concept as a basis for inventing the world’s first solar water heater. Kemp’s creation was simply a water tank inside a black box placed in direct sunlight.
Water heating technology has improved by leaps and bounds. Today, there are much more sophisticated and efficient solutions on the market, but the principal stay the same: The sun does most of the work.
1876 – 1900s: The first solar cells.
In 1876, Brits William Grylls Adams and his student, Richard Day, further developed the photovoltaic concept. Together, they created the first solar cells when they discovered that selenium produced electricity when it was exposed to light. Selenium was not efficient, but in 1953, Americans Calvin Fuller, Gerald Pearson and Daryl Chapin discovered that silicon is a highly effective alternative. Today, most solar panels are made with silicon PV cells.
2 000s and beyond.
In a report released in October 2017, the International Energy Agency (IEA) stated that solar energy is the world’s fastest growing source of power. According to the IEA, a third of the world w
Image 4: The world’s first solar-powered skyscraper, the Sol Invictus, could see the light in Melbourne in the near future.
ill be powered by the sun by 2060. The future of solar energy is indeed bright, with many modern thinkers coming up with brilliant new ideas for utilising the power of the sun:
Peddle Thorp, an Australian architecture firm, has draw up plans for a solar-powered skyscraper in Melbourne. It is called the Sol Invictus (“invincible sun”) and, while many buildings are built to deflect the harsh sunlight, this skyscraper welcomes it. Everything from its orientation to its oval shape and the height of its windows has been designed for optimal sun exposure. The dream is to fit 400 square meters of solar PV panels onto the roof and cover the façade in 3 500 square meters of solar PV cells.
One company is also paving the way for solar energy-generating roads. The US company Solar Roadways has designed a series of hexagonal tiles that are embedded with solar PV cells and can be placed over existing tarred roads. Each tile holds a 44-watt solar panel and approximately 170 tiles could fully power a standard household. Solar Roadways started testing their prototype in October 2016, when they unveiled an installation of solar tiles in Idaho. The installation is powering a public restroom and a nearby water feature.
The future is here
Today, the latest advancements in efficient, renewable energy are available to just about any homeowner; and it is more affordable than what you might think. Even if you cannot afford to purchase a system straight away, Energy Partners Home Solutions offers various financing options to make it even easier for you to own a home energy system. To find out more, call Energy Partners Home Solutions on 0861 000 606 for a free, no-obligation home energy assessment or visit www.poweryourself.co.za.
Energy Partners, part of the PSG group of companies, has been helping some of South Africa’s most well-known businesses save on their energy costs for over seven years. Energy Partners Home Solutions, a division of Energy Partners, brings the same award-winning solutions to the residential and SME markets by combining state of the art energy efficiency technology, solar PV systems and expertise with Energy Partners Home Solutions’ own advanced products. By partnering with Energy Partners, clients can reduce their monthly electricity bills by up to 70%. For more information visit http://www.poweryourself.co.za/ or contact 0861 000 606.