Solar energy has an interesting history with its first, more primitive uses being as early as the 7th century B.C. The photovoltaic effect was discovered in the year 1839 by French Scientist Edmond Becquerel. Photovoltaic technology as we know it today was officially born in 1954, when Daryl Chaplin, Calvin Fuller, and Gerald Peterson developed the first silicon photovoltaic cell at Bell Labs. Solar panels have come a long way since their invention and have advanced tremendously in recent years.

Today’s solar cells are made of silicon, while their predecessors were made of selenium. In 1873, Willoughby Smith first discovered that selenium had photoconductive potential. Then, in 1876, William Grylls Adams and Richard Evans Day discovered that selenium creates electricity when exposed to sunlight. These discoveries finally led Charles Fritts to invent the first selenium solar cells in 1883.

As previously mentioned, the first silicon solar cell was invented in the 1950s, when Bell Laboratories realized that silicon, a semiconducting material, was more efficient than selenium. At this point silicon solar cells were very expensive to produce, and at just 4% efficiency, they were not a practical choice for most people.

In the 1970s, Congress passed the Solar Energy Research, Development and Demonstration Act of 1974 in an attempt to invest in research to make solar energy more affordable to the public. Due to the energy crisis at the time, people began seriously considering solar energy as an option to power their homes and businesses. In 1978, the Energy Tax Act created commercial and residential Investment Tax Credits (ITCs) to provide more financial incentive for people to install solar. However, the push was not entirely successful, with people critiquing the aesthetics of the panels, and arguing that they were only accessible to the very wealthy. The second push for solar occurred in the 2000s, when the Energy Policy Act of 2005 was passed. This raised the commercial ITC to 30%, and reinstated the residential ITC after a 20 year suspension.

The most notable growth in solar, however, has been over just the past decade. According to the Solar Energy Industries Association, solar has been growing at an average rate of 50% over the last 10 years, and installing solar is more affordable than ever, with installation costs dropping over 70%. To date, the US has a total of 108.7 GWdc of installed solar power and over 3 million solar installations. In 2021, solar power made up more than half of new electricity installations, and the passing of the Inflation Reduction Act in 2022 is projected to even further increase the prevalence of solar energy.

PV technology has made huge strides in the 70 years since it was first invented, with the efficiency of today’s solar panels reaching up to 42%. As researchers work on further advancing solar technology, its efficiency will likely continue to increase making it more and more valuable as a renewable energy source.