Solar energy may seem like a modern development, but its story actually dates back nearly two centuries. The discovery of the photovoltaic effect in 1839 laid the groundwork for today‘s solar panels, but it would take many decades of innovation to transform this novel concept into the high-efficiency energy source we know today. From the earliest days of solar-powered satellites to modern rooftop arrays and utility-scale solar farms, this is the complete history of solar energy—and a look at its exciting potential in the years to come.
The Birth of Solar Energy
The story of solar energy begins in 1839 with the work of French physicist Edmond Becquerel. In experimenting with metal electrodes and electrolyte solutions, Becquerel discovered the photovoltaic effect—the creation of electric current in a material upon exposure to light. This groundbreaking finding showed that it was possible to convert sunlight into electrical energy.
Other scientists and inventors soon began experimenting with solar cells made of materials like selenium. In 1883, American inventor Charles Fritts designed and built the world‘s first rooftop solar array, installing it on a New York City rooftop. Fritts used selenium wafers to generate an electrical current. While this prototype achieved only around 1% efficiency, it provided an early demonstration of solar energy‘s potential for practical use.
Early 20th Century: Slow But Steady Progress
Developments in solar energy technology continued at a slow pace in the early 20th century. A key breakthrough came in 1905 with Albert Einstein‘s paper explaining the photoelectric effect, for which he later won the Nobel Prize in Physics. Einstein‘s work focused on the particle nature of light and the idea that light contains packets of energy called photons. This improved scientific understanding of the mechanism behind the photovoltaic effect.
The first silicon-based solar cells emerged in the 1940s but remained prohibitively expensive for most applications. The technology got an important boost with the dawn of the Space Age. As the U.S. and Soviet Union raced to launch satellites and spacecraft, solar energy offered an attractive way to generate power far from Earth.
The Space Race Takes Solar to New Heights
In 1958, the U.S. launched Vanguard 1, the first solar-powered satellite. Its radically new power system, made up of six solar panels, enabled it to remain in orbit for over six years. Other solar-powered satellites followed, including NASA‘s Nimbus and Soviet spacecraft like Sputnik 3.
As the Space Race accelerated in the 1960s, solar energy became an essential component of longer space missions. The compact, lightweight Ranger moon probes employed solar arrays with thousands of solar cells to power their systems and experiments. The Mariner 2 probe, the first successful interplanetary spacecraft, used solar cells to provide power during its flyby of Venus in 1962.
These early applications demonstrated solar energy‘s unique advantages for space exploration. With no moving parts and ability to generate power indefinitely, solar arrays proved much more practical than batteries for long-duration missions. As NASA pushed further out into the solar system in the 1970s, photovoltaics became the standard power system for its spacecraft and remains so today.
The 1970s Oil Crisis Spurs a Solar Revolution
Back on Earth, solar energy technology continued to advance gradually through the mid-20th century but remained uncompetitive with cheap, readily available fossil fuels. This began to change with the 1970s oil crisis, as skyrocketing oil prices and uncertainty in global energy markets highlighted the need for alternative energy sources.
The oil crisis spurred new government and private investment into solar energy around the world. In the United States, the federal Solar Energy Research Institute (now the National Renewable Energy Laboratory) was created in 1977 to drive innovation in photovoltaics. Germany and Japan also emerged as early leaders in solar technology and manufacturing during this period.
By 1980, the global solar industry had grown to over 500 megawatts of annual production. Costs were dropping rapidly, with the price per watt of solar modules falling from around $100 in 1975 to under $10 a decade later. While still a tiny fraction of overall energy generation, solar was becoming an increasingly viable technology. The stage was set for a solar energy revolution.
Exponential Growth and Falling Costs: The Modern Solar Era
The past four decades have seen solar energy truly come into its own as one of the fastest-growing energy sources worldwide. The numbers tell a story of exponential growth:
- In 1983, worldwide solar photovoltaic installations totaled just 21.3 megawatts. By 2021, that figure had grown to over 843,000 megawatts—nearly a 40,000-fold increase.
- The cost of solar has plummeted by over 85% just since 2010, making it cost-competitive with fossil fuels in many areas. Remarkably, solar is now the cheapest source of new electricity generation for over two-thirds of the global population.
- Solar accounts for nearly half of all new electricity generation capacity added globally each year, a share that continues to rise. Solar could meet 20% of worldwide electricity needs by 2030 in a sustainable development scenario.
This exponential growth stems largely from two factors: steadily improving solar technology and economies of scale as the industry has matured. Solar cell efficiency has more than doubled since the 1970s while new materials and manufacturing techniques have brought costs down. Governments around the world have also provided subsidies, tax incentives, and other policies to accelerate solar adoption.
The result of these converging trends has been a solar energy landscape transformed. At the turn of the millennium, solar supplied less than 0.01% of global electricity generation. Today, it has grown to over 3%—still modest but rising rapidly year after year. In countries leading the way like Germany, Italy, and Australia, the solar share of electricity already exceeds 10%.
Modern Solar Technology and Applications
Solar energy technology has come a long way from the days of inefficient, expensive solar cells. Modern solar panels leverage several key innovations to achieve record-breaking efficiency and cost-effectiveness:
- Monocrystalline silicon: Most of today‘s solar cells are made from thin wafers of crystalline silicon. Monocrystalline cells, made from a single silicon crystal, offer the highest efficiency—over 25% for high-end models.
- Multi-junction cells: For specialized applications like satellites and spacecraft, multi-junction solar cells layer several semiconductor materials to capture a wider range of light wavelengths. NASA‘s advanced multi-junction cells can achieve nearly 40% efficiency.
- Solar concentrators: Large lenses and mirrors can focus and concentrate sunlight onto a smaller area of solar photovoltaic material, boosting efficiency and reducing system costs. Concentration ratios from 2x to over 1,000x are possible.
- Bifacial modules: An emerging solar panel design places photovoltaic material on both the front and back of the module. This allows the rear side to capture and convert light reflected from the ground or another surface behind the panel.
- Anti-reflective coatings: Thin coatings applied to the top surface of solar cells reduce reflection and allow more light to enter the semiconductor material. These highly-transparent coatings can boost efficiency by several percentage points.
These and other advances in photovoltaic technology have enabled solar energy to prove itself in an ever-expanding range of applications. Some of the most noteworthy include:
Utility-Scale Electricity Generation
The most high-profile application of solar energy is in massive solar farms that supply power to regional electrical grids. The largest is the 2.2-gigawatt Bhadla Solar Park in India, with over 10 million solar panels spread across 5,700 acres. The United States is home to several projects approaching or exceeding 1 gigawatt, led by the under-construction Samson Solar Energy Center in northeast Texas.
Distributed Rooftop Solar
Just as important as massive utility-scale projects is the rise of distributed solar on homes and businesses. Falling costs have made rooftop solar power an attractive investment for millions of property owners around the world. In Australia, over 30% of all homes have rooftop solar panels, while the share in the U.S. is around 3% but growing fast. With energy storage solutions like the Tesla Powerwall, these systems can provide backup power and reduce reliance on the electrical grid.
Solar Lighting and Off-Grid Applications
Solar is increasingly being used to provide lighting and power in areas without access to electrical grids. From streetlights to phone chargers to water purification systems, solar solutions are proving themselves from the most remote villages to forward operating bases. Solar-powered lights have been used to reduce reliance on dangerous and dirty kerosene lamps in developing nations.
Solar Heating and Cooling
While photovoltaic systems that produce electricity dominate the solar industry, solar thermal technology also plays an important role. Solar water heaters use the sun‘s energy to provide hot water for homes, hotels, hospitals and other facilities at a fraction of the cost of electric or gas-powered systems. Solar air conditioning, which uses heat from the sun to drive cooling processes, is also gaining traction.
The Future: Solar Energy‘s Vast Potential
For all the progress solar energy has made in recent decades, it still represents just a tiny sliver of global energy production dominated by fossil fuels. But with the cost of solar continuing to fall and the urgency of climate change demanding a rapid transition to clean energy, many experts believe solar is poised for even more explosive growth in the coming decades.
The International Energy Agency projects that solar could become the largest source of global electricity generation by 2050 under its sustainable development scenario, providing nearly 30% of worldwide electricity. Other studies suggest solar could meet the majority of energy demand in many regions with abundant sunshine and available land.
But fully realizing solar energy‘s potential will require overcoming several obstacles and limitations. One is that solar power is inherently intermittent—no energy is produced at night or when skies are cloudy. Affordable, long-duration energy storage solutions are needed to alleviate this issue and allow solar electricity to be dispatched as needed.
Integrating increasing amounts of solar into electrical grids is another challenge that will require upgrades to transmission infrastructure, more advanced distribution electronics, and new tariff and compensation models. Concerns around land use for large solar farms and proper disposal and recycling of old solar panels must also be addressed.
Despite these and other challenges, there is good reason to believe the best days for solar energy lie ahead. The convergence of steadily improving technology, falling costs, government support, and growing public demand for clean energy continues to power solar‘s rise around the world. And its vast, virtually limitless energy potential means we have only just begun to tap what solar can ultimately provide.
The scientist and innovators who first harnessed the power of the sun nearly two centuries ago probably never imagined the technology would come so far so fast. But if anything, the story of solar energy is still just beginning. With the potential to cleanly and affordably meet humanity‘s energy needs for generations to come, solar power will no doubt be at the center of our ongoing efforts to create a sustainable future. The history of solar energy is still being written, and the years ahead are looking bright indeed.
