Solar panels are now a familiar sight on rooftops, but their journey from a rare curiosity to the most affordable source of electricity is a fascinating one. To understand how we got here, we spoke with John Perlin, author of a book on the history of solar power. He reveals surprising twists and turns in the technology’s development, shedding light on where it might be headed next.
To understand the evolution of solar panels, we need to grasp the basics of photovoltaics. Electricity is the flow of electrons. Some molecules lack electrons, while others have an excess. With enough energy, electrons can jump from one molecule to another, creating an electrical current. Solar panels harness this process. They consist of two silicon wafers: one with an excess of electrons (N-type) and another with a deficiency (P-type). When sunlight hits the N-type layer, it dislodges electrons. These electrons initially fill the holes in the P-type layer, but these gaps quickly fill up, creating a depleted area where the two layers meet. Electrons can’t easily cross this area, but there’s an alternative route that powers our devices. Thin conductive strips on the top of the N-type layer guide electrons through an inverter, which converts direct current into usable alternating current. The electrons then flow through our appliances. Finally, they return to the P-type layer, completing the circuit. This process continues as sunlight reaches the P-type layer and dislodges electrons, starting the cycle anew.
The first recorded photovoltaic solar panel was installed in New York City in 1884 by Charles Fritts. Building upon the work of French physicist Edmond Becquerel, who had created the first individual solar cell, Fritts’ panel was only 1% efficient. Another inventor, George Cove, focused on using the sun’s heat to generate electricity, a concept that persists today in thermoelectric generators. However, Cove’s work was shrouded in controversy. Following significant investment, he was allegedly abducted by American capitalists, perhaps to halt his work or because his solar panel was suspected of drawing power from the grid rather than generating its own. Whatever the truth, the rise of coal and oil overshadowed these early solar panels for decades.
Einstein’s groundbreaking work on the dual nature of light as a wave and a particle had profound implications for solar panels. He demonstrated that shorter wavelengths of light carried higher energy, but they didn’t penetrate materials deeply. This meant solar panels needed to have their active elements closer to the surface to capture these high-energy photons. This discovery reignited interest in solar technology.
The promise of solar power resurfaced in the world of telecommunications. In the 1950s, Bell Labs was searching for an alternative to the unreliable dry cell batteries used in tropical climates. Daryl Chapin, the lead researcher, explored solar power as a solution. A key advancement was the introduction of impurities, known as ‘doping’, into silicon. This significantly improved its performance as a semiconductor. Doping the upper layer with phosphorus increased the number of electrons, while doping the lower layer with boron created more electron holes. This disparity in charges enhanced electron flow, boosting efficiency to 6%. Solar panels were finally ready for real-world use.
The Space Race further propelled the development of solar power. Satellites relied on batteries that quickly depleted, limiting their lifespans. The U.S. government sought solutions for an edge in the Cold War. Hans Ziegler, a former Nazi scientist who had come to the U.S. under Operation Paperclip, proposed using solar cells for satellites. His first test on the Vanguard 1 satellite in 1958 was a success, enabling communication for over six years, much longer than expected. Vanguard 1 is still in orbit today. Solar power became the standard for all satellite launches.
In a surprising twist, Exxon, a company often seen as an enemy of the climate movement, played a critical role in the commercialization of solar power. Exxon’s remote operations relied on expensive batteries, creating environmental problems when they were discarded. Seeking alternatives, they partnered with researcher Elliot Berman, who had been promoting solar power. Berman established Exxon’s Solar Power Corporation, where he innovated cost reduction strategies. Instead of using expensive monocrystalline silicon, he utilized polycrystalline silicon from scrapped panels and the wider electronics industry. This approach, though less efficient, was significantly cheaper. With solar’s success in space and reduced costs, Exxon started using solar panels on their platforms, leading other industries to adopt solar for their remote operations.
America’s quest for energy independence in the wake of the 1973 oil crisis further influenced the development of solar. While Exxon diversified, solar was not a top government priority. Despite Jimmy Carter’s promotion of solar alongside energy conservation, his policies favored nuclear power and coal. Ultimately, America discovered more domestic oil reserves, leading to a surplus throughout the 1980s.
China emerged as a new center for solar panel development. Australia’s telecom providers, facing challenges similar to Bell Labs in the 1950s, invested in solutions, including the development of PERC technology by Martin Green at New South Wales University. PERC reduced heat absorption, allowing solar panels to operate at high temperatures, and increased efficiency to 25%. Today, 90% of solar panels use PERC cells. Green’s technology found fertile ground in China, which lacked the fossil fuel ties that hampered development in Australia and America. Green’s Ph.D. student, Shi Zhengrong, founded Suntech, a solar cell manufacturer that capitalized on the Chinese market and government incentives for renewable energy. Suntech’s success attracted investment from American experts, becoming the first Chinese private company to list on the New York Stock Exchange. Intense competition among Chinese manufacturers drove down prices, making solar panels more accessible. Despite the 2008 financial crisis, many Chinese manufacturers secured early American investment and ramped up production, ensuring continued low prices. The cost of solar panels has plummeted from $100 per Watt to under $3 per Watt.
Solar power has come a long way. Early research, space exploration, and Exxon’s innovation combined with China’s manufacturing prowess have made solar energy the affordable, ubiquitous technology it is today. While the future may not involve every roof having a solar panel, large-scale solar power plants are poised to play an even greater role in powering our world. The history of solar panels offers a fascinating glimpse into the evolution of a technology that has the potential to reshape our energy landscape.
