The history of solar PV

Solar panels may feel like a modern invention, but humans have actually been harnessing the power of the sun for thousands of years. In this article, we’re going to take a brief look at the history of solar PV, from its humble beginnings to the exciting possibilities it holds for the future.

Early uses of solar PV

The first stage in the development of solar technology was the use of glass to concentrate the sun’s rays, allowing humans to create fire.

There’s evidence of this all the way back to the 7th Century BC, while ancient Greeks and Romans were known to use mirrors to light torches. Legend even has it that Ancient Greek mathematician Archimedes used a ‘heat ray’ made from a large mirror or glass to burn approaching enemy ships during the Siege of Syracuse.

While these tools helped us to concentrate the power of the sun, they could only be used while the sun was shining. It wasn’t until the 18th Century that a way to store solar energy for later use was found.

The first solar cell

The creation of the first solar collector, or cell, is credited to Swiss scientist Horace de Saussure in 1767.

The increased use of glass during the 18th Century made more people aware of its ability to trap solar heat, with a general understanding that a room is made hotter when the sun shines through the glass. Unlike his contemporaries, who were using burning mirrors, de Saussure experimented with glass, creating a heat trap using an insulated box with an opening at the top and laters of glass inside, able to heat the interior to over 110°C.

Several 19th-Century scientists continued to experiment and improve upon de Saussure’s hot boxes. A notable example of this was the astronomer John Herschel, who made a hot box during his expedition to South Africa in the 1830s, which he used to cook meat and eggs and boil water. In the 1860s, French mathematician August Mouchet constructed the first solar-powered steam engines, which would become the predecessors for modern solar parabolic dishes.

The scientific discoveries behind solar panels

A key milestone in the invention of solar panels came in 1839, when French scientist Edmund Bacquerel discovered what is known as the photovoltaic effect. When experimenting with the generation of electricity using two metal electrodes placed into a conducting solution, Bacquerel found that exposure to light could increase the production of electricity.

In 1883, American inventor Charles Fritts used this discovery to create a solar cell made using a coating of the semiconductor selenium, with a thin layer of gold to act as the junction. While this device was only around 1% efficient, it was the first invention made from solid material that could convert sunlight directly into electricity with no moving parts.

Scientists then began to work towards increasing the efficiency of photovoltaic cells. The photoelectric effect, in which electrons are released from solids, liquids or gases when they absorb energy from light, was a key discovery in the pursuit of harnessing solar energy. In fact, theoretical physicist Albert Einstein won a Nobel Prize in physics for his paper on the photoelectric effect in 1921.

The development of modern solar cells

In 1908, William J. Bailley of the Carnegie Steel Company invented a solar collector that used copper coils inside an insulated box, which is roughly the same design that we use today. Engineer and researcher Russell Ohl then went on to patent the modern semiconductor solar cell in 1946, with his work leading him to create the first silicon solar cells, and paving the way for modern diode technology such as LEDs.

By the mid-20th Century, the study of global warming and the depletion of natural fuels had become international news, and the need for a renewable energy source was identified. This increased interest in solar power led to the development of the first photovoltaic cell that was capable of powering everyday electrical equipment by Bell Telephone Laboratories in 1954. Bell’s cells were able to achieve 4% and later 11% efficiency.

From here, the developments came quicker than ever, with far more than can be listed in this brief overview. Solar PV was initially used to power the radios of the Vanguard I space satellite and quickly became the standard power source for satellites, and is still used today. While there were many attempts to commercialise solar PV, it was slow to take off, until technological developments in the 1970s dramatically reduced the cost of generating solar power.

In 1977, the U.S. Department of Energy (DOE) launched the Solar Energy Research Institute to focus on harnessing power from the sun. By 1982, the DOE had begun operating Solar One, a project in California’s Mojave Desert that was able to establish the feasibility of solar-thermal power tower technology. Solar Two followed in 1996, and demonstrated how solar energy can be efficiently stored for use when the sun isn’t shining.

Domestic solar PV today

Today, solar PV technology has become much more widely available, with more than 1.3 million homes in the UK having solar panels installed. As well as helping to reduce the carbon footprint of the occupants, solar panels can reduce energy bills or, thanks to various government schemes like the Smart Export Guarantee, could even generate income by allowing them to sell unused power back to the National Grid.

However, as the popularity of solar PV increases, and the technology continues to develop, issues surrounding the proper decommissioning and recycling of solar panels have come to light. With global solar waste set to reach 78 million tons by 2050, it’s important that proper initiatives are put in place to ensure that as much material is recycled as possible, allowing us to continue to benefit from this environmentally friendly method of generating electricity.

Enjoyed learning about the history of solar PV? Take a look at our article exploring the history of electric vehicles.