The first rooftop solar panels were installed in 1883

The first practical silicon solar cell was developed at Bell Labs

In 1953, scientists at Bell Labs attempted to develop a power source for phone systems in remote locations, as the dry battery cells lacked the necessary longevity. They experimented with solar power, but the selenium solar cells of the time were too inefficient, eventually leading to the usage of silicon.

Enough sunlight hits Earth in just 90 minutes to power the planet for an entire year

Despite this, in 2023, only 5.1% of electricity in the US came from solar energy. Solar panel technology has nonetheless made significant advancements since the 19th century, largely due to NASA's efforts in the space race.

The Ancient Chinese harnessed solar power for heating and cooling 6,000 years ago

Neolithic Chinese homes faced south for winter sun warmth, while overhangs shielded them from high summer sun. These efforts also influenced urban planning, with cities aligning streets east-west for optimal solar exposure.

The first scientifically useful photograph of a total solar eclipse was taken in Königsberg, Prussia, on July 28, 1851, using a silver-coated copper plate with a light-sensitive chemical layer.

The world's first geothermal power plant was built in 1913 in Devil's Valley

In Tuscany, Italy, Prince Piero Ginori-Conti of Trevignano established the plant nine years after creating a generator that powered five light bulbs using steam vents in the area. Within three years, a second plant was built with two generators, each with 10 times the energy output of the first.

Niagara power helped electrify early New York City

Tesla's AC system at Niagara Falls was so successful that electricity generated there lit up Broadway theaters and powered NYC's subway system in the early 1900s.

View an interactive chart of energy conversion efficiencies for various photovoltaics

This National Renewable Energy Laboratory visualization provides maximum confirmed efficiencies for nearly 30 research PV cell technologies from August 1975 to today. Concentrator multi-junction cells have led the field since 1993. (Desktop recommended site.)

In the photovoltaic effect, light generates electricity by creating a charge imbalance after knocking electrons out of atoms in the semiconducting materials of solar cells.

View historical records of solar observations and discoveries, from telescopes in the early 1600s revealing sunspots to NASA's Parker Solar Probe photographing the sun from within its outer corona in 2025.

Thomas Edison created the first strand of electric Christmas lights in 1880

Edison strung electric bulbs outside his laboratory in 1880, and his business partner Edward H. Johnson first wrapped a tree in lights in 1882. It wasn’t until the lights were commercialized in 1917 that they became common in household Christmas decorations.

The International Space Station is powered entirely by large solar arrays

Launched in 1998, its original solar panels were designed to withstand no more than 20 years of wear from temperature swings and micrometeoroid impacts in space. Replacement panels that roll out like carpets have since been installed.

Solar panel manufacturing begins with silicon extracted from sand

The silicon is purified and shaped into wafers less than 0.2 millimeters thick, coated and connected through a criss-cross pattern of narrow and wider metal, followed by multiple rounds of lamination before bonding to a weatherproof panel.

Explore a gallery of electric vehicles from before 1920

In 1884, Thomas Parker invented the first practical electric car in London. By the turn of the century, early EVs were seen on the streets of Washington, DC. Automaker promotional materials included photographs of cars on mountain roads and other terrains.

The world's first AC hydroelectric power plant incorporated Tesla's engineering

Built at Niagara Falls, New York, the plant alternating current electricity was hailed as the future of power generation. Tesla's fascination with Niagara Falls is traced to his seeing a photo of the waterfalls when he was still a child.

Nikola Tesla's original laboratory was recognized as a historical site in 2018

Beginning in 1901, the Wardenclyffe Tower was built on Long Island, New York to transmit electrical power through Earth's atmosphere. The project was abandoned before becoming operational due to limited funding, and was demolished for scrap in 1917 to help pay off Tesla's debts.

Tesla's first successful AC prototype used a metal shoe polish tin for a rotor

After leaving his position working with Thomas Edison, Tesla partnered with George Westinghouse to promote alternating current systems as a more viable, scalable solution to electricity transmission.

Nearly 40% of American cars were electric in 1899

They were most common in cities, where battery swap stations allowed drivers to "refuel" their vehicles reliably. Innovations in combustion engines caused electric cars to lose ground until environmental policies and advances in battery technology revitalized interest.

Solar energy alone can fully power the world if transmission hurdles can be resolved

When light strikes a photovoltaic cell, electrons are loosened, which travel through a circuit where the energy can be used. Distributing energy from high solar intensity regions and storing energy for non-daylight hours is logistically challenging and costly.

Solar power is converting the sun's energy into thermal or electrical energy

Solar energy is the most abundant renewable energy resource. It can be captured in photovoltaic cells to generate electricity, solar heating and cooling technologies for temperature control, and concentrated solar power to drive steam turbines.

A 1,000 square kilometer patch of solar panels in Africa can power most of Europe

The $500 billion Desertec initiative would have constructed massive solar farms in the Sahara and expansive electrical transmission networks across continents. However, the plan was built on concentrated solar power technology, which is more expensive and less practical than photovoltaics.

Space-based solar power systems may beam energy to Earth

Researchers have successfully collected power from solar panels on a plane and transmitted it to a receiver on Earth's surface, achieving a milestone for space-based energy. The proof of concept is a precursor for a satellite-based solar farm that would transmit energy 24 hours a day.

Thomas Edison publicly executed animals with AC to convince the public of its dangers

J.P. Morgan first backed Thomas Edison's direct current system, seeing electricity's potential to usurp John D. Rockefeller's kerosene empire. Despite the investments and smear campaign against alternating current, alternating current ultimately won public support after lighting the 1893 World's Fair, after which Morgan would fund Tesla's wireless transmission tower.

Light therapy was widely used as a medical treatment for various maladies in the early 1900s before it was replaced by antibiotics.

View US solar energy industry trends and trajectories, tracked by SEIA

The Solar Energy Industries Association provides charts summarizing the state of solar energy in the US, including cumulative solar installations, solar jobs, photovoltaic pricing and deployment, and inflation and supply chain constraints within the market.

The first nuclear reactor was built three years after nuclear fission was discovered

After learning that large atomic nuclei release energy upon being split apart, scientists quickly researched how to control the reaction to make electricity. Fusion—combining small atomic nuclei—generates massive energy in stars and hydrogen bombs.

See how New York City has grown since 1609

Wall Street and the southern tip of Manhattan were the first parts of the island to be developed beyond farmland by Dutch and English settlers. It wasn’t long until New York City resembled the city we know today.

The Rockefeller Center Christmas tree was first erected in 1931 by construction workers

The tradition of erecting a tree in Rockefeller Center officially began two years later, when the company continued what the Depression-impacted workers had started. Today, its lighting and nearby ice skating draw millions annually, making it one of America’s most famous holiday traditions.

Establishing the wind power grid required incentives, reliability, and affordability

Although wind was harnessed to generate electricity for individual buildings in the late 1800s, high costs, mechanical issues with turbines, and better fossil-fuel alternatives delayed wind power's widespread growth. After the oil crises of the 1970s, governments sought alternative energy sources and, in the decades that followed, provided tax credits to expand the wind power market.

The first glasshouse was constructed in 1931

The Maison de Verre in Paris was built to house a doctor's office on the ground level and an apartment upstairs. Unlike the typical model that would follow, this glass house exposed very little of the home's interior.

See Rockefeller Center's Christmas trees since 1931

In 1931, with construction still underway, Rockefeller Center's very first Christmas tree was erected out front. John D. Rockefeller himself greeted the construction workers who put up the first 20-foot tree and decorated it with cranberries and paper garland.

Solar panels can create pollinator-friendly habitats by protecting flowering plants

An example of agrivoltaics, where land is used for solar energy production and agriculture, the panels provide clean energy while also shading plants from excessive sunlight. Pollinator-friendly plants can improve water quality and reduce soil erosion by obstructing the wind.

As of 2022, just 0.5% of installed renewable energy capacity worldwide is geothermal

Despite being able to generate electricity regardless of the weather, solar (28%) and wind (27%) are far more prevalent, primarily because of their lower upfront costs. Geothermal plants use 88% less space than solar farms to produce the same energy, but have been restricted to geologically active regions.

The history of the North American power grid, which is composed of five major grids

Thomas Edison's Pearl Street Station was the first US commercial power plant, burning coal to power lamps for some Manhattan residents. Over time, local power plants would be bought out by larger ones, forming interconnected systems spanning multiple states. Today, the Eastern Interconnection and Western Interconnection are the largest of these systems.

Watch a timeline of the history of electricity, from observations of static electricity in antiquity to the War of the Currents—a rivalry to establish the ideal system for electric grids.

The solar noon clock outside Rhodes Hall at Cornell is named after Bill Nye

In addition to displaying the analog time, the clock's face features an indicator disc that illuminates, even on cloudy days, whenever the sun reaches its highest point in the sky. Nye developed the initial apparatus designs, which were later co-engineered and built by Cornell staff and students.

Electric grids that rely on solar power must compensate for reduced electricity generation during solar eclipses.

Explore a gallery of Bill Nye's energy-efficient home

The Southern California home is painted pale yellow and features double-pane, low-emissivity glass windows to help keep temperatures low. Solar panels are used for electricity and hot water, while Solatube domes and ducts illuminate rooms from above throughout the day, even when the sun is low in the sky.

View US maps of average daily solar resources and solar-based electricity generation

The state you live in can drastically change how much solar energy you can expect to capture to power your home. These National Laboratory of the Rockies maps show where you can reliably generate solar resources.

Benjamin Franklin described a series of static electricity storage jars as 'batteries'

Discovered over 50 years before the first electrochemical cell was invented, Leyden jars stored electric charge between the metals inside and outside a liquid-filled container. Franklin was the first to use the term "battery" in an electrical sense, though his multiple-jar device—lacking chemical reactions—was actually a series of capacitors.

Explore global solar resources with this interactive map

One of the biggest challenges to deploying solar panels is whether electricity can be generated reliably when needed, day after day. This detailed interactive map calculates the solar power output potential of regions worldwide and provides a visual comparison between locations such as North Africa and the US Midwest.

The first American roller coaster was built at Coney Island

LaMarcus Thompson was an inventor and businessman who developed the first US amusement park ride in the 19th century and sparked a booming business. Customers spent a nickel to coast on wheeled benches over gentle hills, leaving Thompson with around $600 per day in profits.

Larger shares of solar power generation produce larger energy demand curves

Because solar energy is only available during daylight hours, transitioning an electric grid to solar requires significant ramp-ups and ramp-downs of other energy sources during mornings and evenings to compensate. Widespread adoption of affordable energy storage solutions can soften these curves.

The first US stock exchange dates back to the 1790s in Philadelphia

Only two years after that stock exchange in Philadelphia started, the largest stock exchange in the US to date was created: the New York Stock Exchange.

A dispute about the origin of twitching frog legs led to the invention of the first battery

Experiments by Luigi Galvani on exposed frog leg nerves showed activity when they were hung from iron railings and brass hooks, suggesting the existence of "animal electricity" that discharged when connected to metals. Alessandro Volta's voltaic pile, which stacked metals with an inorganic electrolyte, showed that electricity originates from chemical reactions.

A collective effort from multiple scientists and inventors led to the light bulb

While Thomas Edison's thin carbon filament design made light bulbs commercially viable, prior contributions, such as Joseph Swan's development of the first successful incandescent filament electric lamp, made its eventual invention possible.

The State of the Union address was first delivered in New York City

The first address took place in New York City in 1790, when President George Washington addressed Congress at Federal Hall—the nation's capital under the Articles of Confederation and the seat of the federal government during the Constitution's first year.

In 1880, Jacques and Pierre Curie discovered that electricity could be produced by striking certain materials—the piezoelectric effect—a phenomenon that is seen in barbecue lighters.

Unlike solar panels, which convert sunlight directly into electricity, concentrated solar power systems focus sunlight to heat a material that boils water, which then drives a turbine-generator to produce electricity.

See photos of ultraviolet light therapy, widely administered in the early 1900s, particularly among children with skin diseases, tuberculosis, rickets, and more.

Clean energy technologies are more mineral-intensive than burning fossil fuels

Solar panels use silver due to its high conductivity, hydropower plants use chromium in their steel alloys, and geothermal plants need titanium to withstand abundant heat and pressure. Lithium—used in energy storage—is expected to see over 500% increased demand from 2020 to 2025.