We hear about solar power all the time, but what exactly is it?
We at AMLI love renewable energy and the positive impact it has on the environment and our lives. Here’s a bit about this renewable power source and the science behind how it works!
Solar power and how it works
The history of solar power
Early solar usage
Since the dawn of time, humans have been harnessing the power of the sun in a wide variety of capacities. Society’s understanding of how the sun affects everything from agriculture to time to curing meats and navigating open oceans has allowed humanity to excel and thrive on our planet, leading many to revere the sun as the very source of life itself.
But inventors and thinkers have long been searching for ways to utilize sunlight to perform more complex tasks like heating structures, powering machines and even creating pure energy from harnessing its rays.
Historians believe that humans were using magnifying elements to create fire from sun rays as early as the 7th century B.C., and that by the 3rd century B.C. the Romans were using mirrors to light torches. This same practice was documented by Chinese writers in the 1st century A.D.
Using the sun to heat up indoor spaces was a common practice in many cultures around the world. Ancient Romans and Greeks used large windows to heat up bathhouses and give them the hot, steamy environment that made them so popular. In the 13th-century-North America, the Anasazi built their pueblos facing south so that the sun could keep their homes warm during winter months. Generally, people built their homes facing certain directions to maximize either the sunlight or shade indoors, especially in crowded cities.
By the 18th and 19th centuries, inventors had figured out how to harness sunlight to help power machines like steamboats and ovens!
Researching the process of utilizing solar power for electricity began in earnest in 1839 with Edmond Becquerel, a French scientist whose area of interest lay in the study of light and its properties. While experimenting in a lab one day, a young Becquerel found that two platinum electrodes placed in a chloride and acid solution could generate voltage when exposed to light. This effect became known as the photovoltaic effect, and it became the basis of solar power development moving forward.
In 1873, scientists discovered that the element selenium could potentially be used to conduct light, and three years later experiments proved that selenium exposed to sunlight could create electricity. In 1883, the first selenium wafer was created to conduct light into electricity, and while solar wafers today are made from silicone rather than selenium, those early wafers were considered to be the first iteration of a solar cell in human history. It was in 1954 that the first silicon solar wafer was invented by Daryl Chapin, Calvin Fuller and Gerald Pearson, kicking off true modern solar technology development.
The world of solar technology has grown rapidly since the mid-1800s.
The very first solar panels in space made their appearance in 1958 when the United States sent Vanguard 1 into orbit. A few years later in 1964, N.A.S.A. launched the Nimbus spacecraft, a fully solar-powered satellite, into space.
Back here on Earth, the University of Delaware unveiled the first solar building called Solar One in 1973, a revolutionary construction, which ran on a mixture of solar and thermal energy. The very first solar-powered plane flew across the English Channel in 1981, and by 2016 the first solar-powered flight around the world was completed by Bertrand Piccard.
As technology continued to advance, so did the efficiency of solar cells. In the 1960s and ‘70s, solar cells could only convert about 8-14% of the light they received into electricity, and by 2016 they could convert upwards of 34.5%! Better technology also means solar power is more accessible and less costly; in 1956 solar cells cost about $300 per watt generated, and in 2018 each watt cost about $0.50! The price has been going down about 10% each year since the 1980s, and it’s likely to keep going down even more!
How does solar power work?
There’s obviously been decades’ worth of work and development to bring us to the solar power technology we have today, but the process of converting sunlight into electricity is not too complicated at its core.
1: Sunlight hits the solar panels
Solar panels are made of two layers (wafers) of silicone cells compressed between thin films and glass panels, all encased within a tempered glass and aluminum frame
Light is made of a stream of photon particles that travel fast enough to create a seamless beam of light. The sun is constantly spitting out sunlight toward us, but depending on the amount of clouds and atmospheric interference, the amount of direct photon interaction varies.
On a bright and sunny day, though, photons hit the solar panels and travel through the glass and film and are absorbed by the silicone cells.
2: Solar cells produce a charge
When the photons hit the silicone cells, the silicone cells activate and start releasing loose electrons. Thanks to the electrical charge generated by the positive- and the negative-charged wafers, the travelling electrons create an electrical charge that’s drawn to the negatively charged side and is collected by a layer of metal fingers.
The electrical current collected by the metal fingers transports the charge from the negative side back to the positive side via an external circuit that deposits electricity to electric-powered devices along the way.
3: The electrical charge is converted
The electrical current created by solar power is a type of current called a direct current (DC), but most homes and machines are powered by an alternating current (AC). Solar-generated electricity requires a conversion machine called an inverter to transform the electricity into a usable format.
4: Running on solar power
Solar power can only be generated during periods of bright sunshine, so at night time and on cloudy days there’s a significant shortage of power from the solar grid. Solar power is also generated whether you’re using it or not, so solar panels may generate a surplus of energy that has nowhere to go in your home.
To accommodate the surplus and shortage of solar-generated energy, solar-powered homes are also hooked up to the main power grid to keep a consistent stream of power. Electricity meters keep track of electricity usage and will send any surplus solar power back into the main grid.
And there you have it! In 2018, four Dallas-area communities installed rooftop solar panels. There’s a lot of science behind this fascinating power source, but it’s something that we can all be a part of.
Featured photo courtesy Pixabay/PublicDomainPictures