Solar Energy Facts & Trivia

If the Sun went out right now, it’d be eight minutes before we knew anything about it – that’s how long the light takes to travel the distance to Earth. Mind you, it would be awfully inconvenient in all sorts of other ways if it did; a bit of darkness would probably be the least of our worries.

Without this 4.57 billion year old nuclear reactor blazing happily away in the sky there’d be no energy down here at all – and that includes all the oil, gas and coal, which is, after all, only a store of ancient solar energy. When you come right down to it, the Sun drives the wind and the waves, and makes everything from photovoltaic cells to photosynthesis possible.

We would, most assuredly, be in a right old mess without it – but how much do you know about our local star and its bountiful supply of energy? If you’re after some fascinating fast facts and solar trivia, then you’ve definitely come to the right place.

The Sun Itself

Let’s start off by looking at the big picture – and when we say big………..

  • The Sun is about 865,000 miles across (nearly 110 times the diameter of the Earth) and around 75% of it is made up of hydrogen.
  • It generates energy from the nuclear fusion of this hydrogen to form helium.
  • The surface temperature of the sun is over 5,500º C.
  • It is a little over 93 million miles from the Earth.

Its Energy

  • Some 174 petawatts (that’s 174 followed by 15 zeros) of solar energy reaches the Earth’s upper atmosphere.
  • About a third of that is reflected back into space.
  • The Earth’s land, sea and atmosphere absorb around 3,850 zettajoules of energy every year – that’s 21 zeros after the 3,850!
  • At that rate, the Earth mops up about as much solar energy in an hour as the whole of the world’s population uses in a year.

From a practical point of view, however, harnessing solar energy fortunately involves things on a slightly smaller scale!

Solar Hot Water

  • Estimates suggest that a well designed system could provide up to 70% of a household’s water heating needs.
  • A typical solar water heating system costs between £3,000 and £5,000.
  • If you currently heat your water by electricity, solar could save you £85 a year – and 580kg of CO2.
  • You only need one square metre of heating panel per person.

Photovoltaic Facts

  • Silicon isn’t just for implants – it’s at the heart of 90% of the world’s PV systems.
  • According to the Energy Saving Trust, a 2 kW (peak) system could provide about 40% of a typical household’s annual electricity.
  • PV doesn’t come cheap – a typical installation might cost up to £14,000 – but it could save you £200 a year in electricity bills and cut your carbon footprint by a tonne of CO2 or more.
  • Since 1st April 2010, the Clean Energy Cashback Scheme means that you could get paid for each unit of electricity your system generates.


Finally, a few well-chosen bits of solar trivia that might just come in handy for your next general knowledge quiz!

  • Helium was named after the Sun (Helios in Greek); it was independently identified spectroscopically during a solar eclipse by both Pierre Jansen and Norman Lockyer in 1868.
  • One Astronomical Unit (AU) is equal to149,598, 000 kilometres – being the average distance between the Earth and the Sun.
  • Charged particles carried in the solar wind interact with the Earth’s atmosphere to cause the Northern Lights or Aurora Borealis and a similar phenomenon – the Aurora Australis – in the southern hemisphere.
  • The Sun has a mass of nearly 2,000,000,000,000,000,000,000,000,000,000kg (yes, that really is 30 zeros) – more than 330,000 times bigger than the Earth – and accounts for nearly 99.9% of the mass of the entire solar system!
  • The Sun has already turned the equivalent mass of more than 100 Earth’s into energy, and will convert the same amount again over the next 5 billion years before it expands to more than 250 times its current size and becomes a Red Giant.
  • It’s surface temperature is rising – very slowly – and it’s also getting brighter but only by about 10% in every billion years!
  • Many cultures over time and across different continents have worshipped the Sun as a god, including the Aztecs (Huitzilopochtli), Celts (Lugh), Egyptians (Ra), Greeks (Helios) and Romans (Apollo).

Whichever way you look at it, there’s an awful lot more to solar energy than simply heating your water!