Though solar energy has found a dynamic and established role in today's clean energy economy, there's a long history behind photovoltaics (PV) that brought the concept of solar energy to fruition. With the way the cost of solar has plummeted in the past decade, it's easy to forget that going solar had a completely different meaning even just 15 years ago. Let's go back a few centuries to the origins of solar PV and explore the history of solar energy and silicon solar technology.
In theory, solar energy was used by humans as early as the 7th century B.C. when history tells us that humans used sunlight to light fires with magnifying glass materials. Later, in the 3rd century B.C., the Greeks and Romans were known to harness solar power with mirrors to light torches for religious ceremonies. These mirrors became a normalized tool referred to as "burning mirrors." Chinese civilization documented the use of mirrors for the same purpose later in 20 A.D.
Another early use of solar energy that is still popular today was the concept of "sunrooms" in buildings. These sunrooms used massive windows to direct sunlight into one concentrated area. Some of the iconic Roman bathhouses, typically those situated on the south-facing side of buildings, were sunrooms. Later in the 1200s A.D., ancestors to the Pueblo Native Americans known as the Anasazi situated themselves in south-facing abodes on cliffs to capture the sun's warmth during cold winter months.
In the late 1700s and 1800s, researchers and scientists had success using sunlight to power ovens for long voyages. They also harnessed the power of the sun to produce solar-powered steamboats. Ultimately, it's clear that even thousands of years before the era of solar panels, the concept of manipulating the power of the sun was a common practice.
The development of solar panel technology was an iterative one that took a number of contributions from various scientists. Naturally, there is some debate about when exactly they were created and who should be credited for the invention. Some people credit the invention of the solar cell to French scientist Edmond Becquerel, who determined light could increase electricity generation when two metal electrodes were placed into a conducting solution. This breakthrough, defined as the "photovoltaic effect," was influential in later PV developments with the element selenium.
In 1873, Willoughby Smith discovered that selenium had photoconductive potential, leading to William Grylls Adams' and Richard Evans Day's 1876 discovery that selenium creates electricity when exposed to sunlight. A few years later, in 1883, Charles Fritts actually produced the first solar cells made from selenium wafers – the reason some historians credit Fritts with the actual invention of solar cells.
However, solar cells as we know them today are made with silicon, not selenium. Therefore, some consider the true invention of solar panels to be tied to Daryl Chapin, Calvin Fuller, and Gerald Pearson's creation of the silicon photovoltaic (PV) cell at Bell Labs in 1954. Many argue that this event marks the true invention of PV technology because it was the first instance of solar technology that could actually power an electric device for several hours of a day. The first ever silicon solar cell could convert sunlight at four percent efficiency, less than a quarter of what modern cells are capable of.
We'll explore some of the biggest events that have occurred in the history of solar energy:
Solar panels in outer space
Some of the earliest uses of solar technology were actually in outer space, where solar was used to power satellites. In 1958, the Vanguard I satellite used a tiny one-watt panel to power its radios. Later that year, the Vanguard II, Explorer III, and Sputnik-3 were all launched with PV technology on board. In 1964, NASA was responsible for launching the first Nimbus spacecraft, a satellite able to run entirely on a 470-watt solar array. In 1966, NASA launched the world's first Orbiting Astronomical Observatory, powered by a one-kilowatt array.
First solar residence
In 1973, the University of Delaware was responsible for constructing the first solar building, named "Solar One." The system ran on a hybrid supply of solar thermal and solar PV power. It was also the first instance of building integrated photovoltaics (BIPV) – the array didn't use solar panels but instead had solar integrated into the rooftop, similar to the design for Tesla's new roof product.
Achievements in solar conversion efficiency
Between 1957 and 1960, Hoffman Electronics made a number of breakthroughs with photovoltaic efficiency, improving the efficiency record from 8% to 14%. The next major achievement was in 1985 when the University of New South Wales achieved 20% efficiency for silicon cells. In 1999, the National Renewable Energy Laboratory collaborated with SpectroLab Inc. to create a solar cell with 33.3% efficiency. The University of New South Wales broke that record again in 2016 when researchers reached 34.5% efficiency.
In 1981, Paul MacCready built Solar Challenger, the first aircraft to run on solar power, and flew it across the English Channel from France to the U.K. In 1998, the remote-controlled solar airplane "Pathfinder" set an altitude record after reaching 80,000 feet. NASA broke that record in 2001 when they reached 96,000 feet with their non-rocket aircraft. In 2016, Bertrand Piccard completed the first zero-emissions flight worldwide with Solar Impulse 2, the world's largest and most powerful solar-powered airplane today.
In 1979, President Jimmy Carter had solar panels installed in the White House during his term as president. However, in 1981, President Ronald Reagan ordered the White House solar panels to be removed. In 2010, President Barack Obama requested that solar panels and a solar water heater be installed in the White House. Both were installed during Obama's first term.
Cost of solar over time
Prices for solar panels have dropped substantially over the past few decades, leading to a surge in consumer demand that has produced more than one million U.S. installations as of early 2016. In 1956, solar panels cost roughly $300 per watt. By 1975, that figure had dropped to just over $100 a watt. Today, a solar panel can cost as little as $0.50 a watt. Consider this: since the year 1980, solar panel prices have dropped by at least 10 percent every single year. The plummeting cost of solar is largely responsible for the growing popularity of solar and the legitimacy of PV as a reliable energy source in today's world.
Regardless of why solar power is interesting to you, there is a robust and fascinating history behind solar's rise to relevant status. Solar has a long list of meanings in today's day and age, spanning various industries and contributing power to hundreds of different gadgets and technologies. Today, solar shopping is easier than ever through EnergySage! Learn just how much solar can save you: try our Solar Calculator to get instant estimates for a solar installation and the energy savings you could generate. If you're ready to start comparing bids from vetted installers in your area, register your property on the EnergySage Marketplace.