Solar Energy
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50 free Solar Energy trivia questions with answers — science & nature quiz, new questions added Oct 2026.
The Sun delivers far more energy than people could ever use, and the story of learning to catch it runs from ancient legends to panels on rooftops and spacecraft. It is a subject full of surprises: inventors who were decades ahead of their time, and machines that run on nothing but daylight. This quiz covers how photovoltaic (PV) electricity works, the materials inside a panel, the history of solar power and the people behind it, home batteries and the grid, enormous solar farms, and solar thermal plants that run on mirrors and stored heat. It suits students revising a science unit, teachers who need a ready-made classroom round, and curious readers who follow clean energy. Every answer comes with a short explanation, so you learn as you play.
30 of 50 questions with answers and explanations. Play the quiz
Q 01By a 2002 estimate, the sunlight Earth absorbs in what span held more energy than the world used all year?
About one hour
About one hour of sunshine carried more energy than humanity burned through in twelve months. By 2019, with demand far higher, the span had stretched to under an hour and a half.
Q 02Which US president put solar water heaters on the White House roof, only for his successor to remove them?
Jimmy Carter
Jimmy Carter's panels heated water for the building until they came down under Ronald Reagan. Barack Obama had new panels fitted to the roof in 2013, the first to power the president's living quarters.
Q 03On which kind of day does a typical solar panel convert sunlight into electricity most efficiently?
Cold and sunny
Cold and sunny days suit panels best, because a solar cell loses roughly 0.45% of its efficiency for every degree Celsius it warms. Cells in full sun often run 20 degrees hotter than the air.
Q 04Which ancient Greek is said to have set Roman ships ablaze at Syracuse by focusing sunlight with mirrors?
Archimedes
Archimedes gets the credit only in later retellings: the three earliest accounts of the siege never mention mirrors. Whether the trick could work has been argued over since the Renaissance.
Q 05Which NASA Mars rover fell silent in 2018 after a planet-wide dust storm starved its solar panels?
Opportunity
Opportunity was built to last 90 Martian days and kept working for more than 14 years. Engineers hoped a windy season would sweep its panels clean, but it never called home again.
Q 06Roughly how long does sunlight take to cross the 150 million kilometres from the Sun's surface to Earth?
About 8 minutes
About 8 minutes pass before light leaving the Sun arrives here. Deep inside the Sun, that same energy spent at least 10,000 years working its way out from the core.
Q 07Which farm animals are most commonly grazed beneath solar farms to keep the vegetation trimmed?
Sheep
Sheep are the usual choice because they can graze among ordinary solar arrays with no changes to the design. In return for the mowing they get forage and shade.
Q 08Which physicist won the 1921 Nobel Prize for explaining how light knocks electrons out of a metal?
Albert Einstein
Albert Einstein won for his 1905 paper on the photoelectric effect, not for relativity. The same physics, light freeing electrons, is what lets a solar cell produce a current.
Q 09Which tiny state roofed its main audience hall with 2,400 solar panels in 2008?
Vatican City
Vatican City put the array on the Paul VI Audience Hall, a gift from a German manufacturer. It was sized to cover the building's heating, cooling and lighting all year.
Q 10Which carmaker launched the Powerwall in 2015, a home battery that stores rooftop solar power for the evening?
Tesla
Tesla announced the Powerwall in April 2015 as a way to bring its car-battery know-how into the home. Only 500 pilot units were built that first year.
Q 11Which process in the Sun's core, turning hydrogen into helium, releases the energy that solar panels collect?
Nuclear fusion
Nuclear fusion forces atomic nuclei together under crushing heat and pressure. The Sun is only about halfway through the stage of its life in which it shines this way.
Q 12In the Northern Hemisphere, which way should a fixed solar panel face to gather the most sunlight?
South
South is the rule above the equator, while panels in the other hemisphere point the opposite way. Installers then set the tilt according to the site's latitude.
Q 13Which element, the second most abundant in Earth's crust after oxygen, is used to make most solar cells?
Silicon
Q 21Which natural process lets green plants store the Sun's energy as chemical fuel, the origin of wood and coal?
Photosynthesis
Photosynthesis locks away about 3,000 exajoules of sunlight in plant matter every year. Fossil fuels are that same harvest from the distant past, buried and compressed.
Q 22Which colour is the absorber plate in a solar water heater usually painted so it soaks up the most sunlight?
Black
Black enamel paint is a common coating for the plate, which sits under glass with the water pipes embedded in it. Dark surfaces absorb the sunlight that pale ones bounce away.
Q 23Which particles strike a solar cell and hand their energy to electrons inside it, starting a current?
Photons
Silicon makes up about 28% of the crust by mass, locked inside the minerals of ordinary rock and sand. Cells cut from its purified crystals dominate the world's solar market.
Q 14Which device turns the direct current from solar panels into the alternating current that homes use?
Inverter
An inverter is needed because panels produce a steady one-way flow, while grid power reverses direction many times each second. Off-grid cabins running on batteries need one too.
Q 15At the 1878 Paris world's fair, Augustin Mouchot won a gold medal for using concentrated sunlight to make what?
Ice
Ice made with solar heat was the showpiece of his steam engine display. Cheap coal soon made the idea look pointless, and his research went no further.
Q 16Which American research lab unveiled the first practical solar cell in 1954?
Bell Labs
Bell Labs credits the cell to Daryl Chapin, Calvin Fuller and Gerald Pearson. The same lab had already given the world the transistor.
Q 17Which country hosts the World Solar Challenge, a 3,000 km race for sun-powered cars first run in 1987?
Australia
Australia's race crosses the outback from Darwin to Adelaide. The first winner, General Motors' Sunraycer, averaged just 67 km/h, and by 2005 the pace had reached 100 km/h.
Q 18Which giant planet did NASA's Juno probe reach in 2016, the first mission there to run on solar panels?
Jupiter
Jupiter gets only 4% of the sunlight that Earth does, so every earlier mission to the planet carried a plutonium-fuelled generator instead.
Q 19Which country overtook Germany in 2015 to become the world's largest producer of solar electricity?
China
China took the lead in 2015 and just two years later became the first country to pass 100 gigawatts of installed solar panels.
Q 20Which 1958 American satellite, the first to carry solar cells, is the oldest human-made object still in orbit?
Vanguard 1
Vanguard 1 is so small that Nikita Khrushchev mocked it as the grapefruit satellite. Its sun-powered transmitter kept sending signals for more than six years.
Photons give up their energy to electrons, and the cell's built-in electric field then sweeps those freed electrons off in one direction.
Q 24Which battery chemistry, the usual choice for home solar storage, won its developers a 2019 Nobel Prize?
Lithium-ion
Lithium-ion cells won the chemistry prize for John Goodenough, Stanley Whittingham and Akira Yoshino. They suit home storage because they pack a lot of energy into a small space and survive many charge cycles.
Q 25In 2016 the Swiss aircraft Solar Impulse 2 became the first piloted solar plane to do what?
Fly around the world
To fly around the world on sunlight alone took Solar Impulse 2 more than 16 months, covering about 42,000 km in stages from Abu Dhabi and back.
Q 26Which small NASA helicopter, recharged by a solar panel above its rotors, made the first powered flight on Mars?
Ingenuity
Ingenuity first rose from Mars in April 2021, hovering 3 metres up for about 40 seconds. A weak winter Sun later left it so short of power that it shut down completely at night.
Q 27Which physicist's name is given to a hypothetical shell built around a star to capture its energy output?
Freeman Dyson
Freeman Dyson set out the idea in a 1960 paper on searching for artificial sources of infrared radiation. His inspiration was Olaf Stapledon's 1937 novel Star Maker.
Q 28The Desertec Foundation, set up in 2009, proposed helping to power Europe with solar farms in which desert?
The Sahara
The Sahara was chosen because parts of it see bright sunshine for up to 97% of daylight time. Studies suggested its sun could also run desalination plants for the region.
Q 29The Sharp EL-8026 and Royal Solar 1 of the late 1970s were early sun-powered versions of which gadget?
Calculator
Calculator makers paired solar cells with liquid crystal displays, which need very little power. Some cheap modern models carry only a dummy panel and really run on a battery.
Q 30Which physicist discovered the photovoltaic effect in 1839, aged 19, in his father's laboratory?
Edmond Becquerel
Edmond Becquerel made his find with a simple electrochemical cell. Science ran in the family: his son Henri went on to discover radioactivity.