Solar power history reveals that mankind has harnessed the energy of the sun in various ways for thousands of years. Below, we'll take a look at some of the more interesting facts and briefly examine the amazing journey that scientists and inventors have taken leading up to today's practical use of solar electricity.
Our overview of solar power history begins at the dawn of time when the earliest cave dwellers chose rock faces with southern exposures to locate their caves and cliff dwellings, taking advantage of the thermal energy generated by the sun during daylight hours to heat their homes.
The early Chinese and Greek civilizations were among the first to orient buildings to the south and to plan their towns around the east-to-west movement of the sun to best provide warmth and light. Meanwhile, the Romans designed their bathhouses and villas with large south-facing windows to gather the sun's energy and warm the interior.
The ancient world learned to focus the sun's rays through water-filled glass vessels and use "burning lenses" to start fires and cauterize wounds. Over the centuries, heat storage containers, ovens, thermometers, and other devices were created that relied heavily on the sun's energy. Such devices were eventually improved upon and became more diverse.
While experimenting with solar radiation in 1767, the Swiss physicist Horace-Benedict de Saussure (1740-1799) made history by constructing the world's first known solar collector, an insulated oven-like box with three layers of glass to trap out the outgoing thermal radiation.
After registering oven temperatures up to 110 °C (230°F) at various locations in the Alps, he proved that the external air temperature had no significant effect on the trapped thermal energy. Sunlight was clearly a potential source of energy.
Solar power history would be incomplete without a mention of the influence of sunlight on agricultural methods. Greenhouses have been used to collect and control solar heat to grow specialty crops since Roman times. During the Medieval Warm Period, or Little Ice Age, vertical "fruit walls" oriented to the south were built of stone to collect the sun's warmth and hasten the ripening of plants in the shortened growing season.
Solar water purification is an ancient and cheap technology that's still being used in remote rural areas of the world, especially in developing countries. The technique can be as simple as a jar of water sitting in sunlight for several hours, or it might involve technology such as a solar still that purifies the water while simultaneously killing disease-causing pathogens.
The sun's warming effect upon water has long been utilized for mankind. As recent as the last century, some public heating systems in the 1920s used large water storage tanks to trap solar energy, and the sun-heated water was then piped to homes. However, such systems fell into disuse as the cost of gas and hydro electric power for heating gradually became cost efficient.
Nowadays, as the cost associated with fossil fuels increases, solar hot water panels have become a common sight on roofs and sun-heated water is commonplace in thousands of homes.
The year 1839 stands out in solar power history as the year when a French experimental physicist named Alexandre-Edmond Becquerel (1820-1891) discovered that ordinary sunlight shining onto an electrolytic material produces measurable electrical current. His discovery of the "photovoltaic effect" opened the door to the possibility of solar electric power, but it would take years for scientific inventions based on his discovery to become practical.
American inventor Charles Fritts developed a crude photovoltaic cell using selenium on a thin layer of gold as early as 1883. The device he formed gave less than 1% efficiency, but it significantly advanced solar power history by opening the door to further refinements and immense future possibilities.
It wasn't until 1954 when Bell Labs invented the first modern silicon solar cell with a 6% efficiency that the solar power industry began to come of age. Since then, there have been never-ending improvements in efficiency and new adaptations made, resulting in lower manufacturing costs for solar cells.
Today, the uses for photovoltaic (PV) cells are near endless and include millions of solar powered highway lights, traffic signs, electric livestock fences, lawn lights, battery chargers, calculators, attic fans, and clean electrical power generation for recreational vehicles, to name only a few.
Physicist Albert Einstein (1879-1955) is best remembered for his Theory of Relativity, but few people are aware that the Nobel Foundation awarded him the 1921 Nobel Prize In Physics "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect."
Einstein's 1905 paper on the "Photoelectric Effect" opened the door to the practical use of Becquerel's discovery for producing photovoltaic energy in today's solar cells.
Here's how Becquerel's photovoltaic effect works in simplest terms:
Sunlight falling on certain materials causes the electrons in their associated atoms to get knocked loose. The loose electrons moving within the material form an electrical current. Once that current is connected to a circuit and its electrical flow is harnessed, it can be used for practical purposes. For example, it can heat a house, illuminate light bulbs, or power a modern wide-screen television. It's this electrical current that's the basis of solar-generated electricity.
Today, there are numerous applications of solar power technology supplying the world's electrical needs. Satellites and planetary rovers use photovoltaic (PV) solar panels to generate needed electrical power while closer to home, PV panels power lights along some highways and even power minor household applications such as security lighting and garden fountains.
Solar power history continues to be written as innovations bring added convenience and cost savings. Portable solar power generators provide an alternative source of electricity for builders, and solar power for RVs is now practical for vacationers. Homes located too far from utility lines can now use off grid solar electricity that's affordable, non-polluting, and 100% renewable.
Not all solar devices are costly. Solar powered plant watering systems, battery chargers, Christmas lights, and calculators cheap enough to be promotional giveaways are present in many homes now.
Home solar power systems remain less common than commercial grid systems, and their installation cost can't yet compete with the big utility companies, but the cost of solar panels continues to fall and solar energy costs are proven to be competitive in the long term, and becoming more so.
The overview of solar power history reveals that the future of solar energy is indeed bright. New discoveries and applications continue to be made. The price of non-sustainable energy continues to rise and the cost of solar power continues to decrease, making it practical and increasingly affordable for the average homeowner.
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