Solar Panels and Space
How solar panels perfected for space exploration revolutionised our renewable energy supplies here on Earth.
A solar makeover
In February 2019 the roof of the National Space Centre got an exciting make over and it is now home to over 700 solar panels.
The solar energy will directly power the running of the Space Centre, generating approximately 174,000 kilowatt hours of energy annually, and saving 67,000 kilograms of carbon.
These solar panels almost completely offset our carbon footprint on the sunniest days and are part of a wider effort by the Space Centre to become more environmentally sustainable.
As well as reducing the amount of carbon used, these panels will also provide shade to the building, helping cool the building down. The largest energy usage currently in the Space Centre is air conditioning, and therefore the solar panels will reduce how much air conditioning is required.
How do solar panels work?
Solar panels work thanks to something called the photovoltaic effect. This occurs when light is absorbed by a semiconducting material like silicon, creating an electric current.
This happens because all materials are made up of atoms, which in turn are made up of protons, neutrons and electrons. The electrons exist in different energy levels and when the light is absorbed these electrons get more energy and means they can move up to a higher energy level leaving a “hole” behind them. When these electrons are in a higher level, they can move through the material and this creates an electric current.
Although the photovoltaic effect was first seen in 1839 it wasn’t until 1883 when the first solar cell was created. Made from gold-coated selenium it was less than 1% efficient – not exactly a viable alternative power source!
About 100 years later, scientists working at the telephone company Bell Laboratories were investigating solar power to find alternate energy sources for telephone systems. They found that some samples of silicon worked much better as a solar cell than selenium and the first silicon solar cell was patented in 1941. Today’s best silicon cells are about 40% efficient and research is ongoing to improve this.
To generate more power, solar cells are connected together into a grid (or ‘array’) in order to make a solar panel.
A brief history of solar panels in space
But did you know that solar panels were perfected in space exploration?
When you send something to space, there are no plugs to power your spacecraft, nor any petrol stations to refuel. Spacecraft therefore have to be powered using either batteries or renewable energy sources such as solar panels or radioactive generators. Solar power is the most readily available power source thanks to the prominence of the Sun, therefore solar power is used for the majority of space missions within the inner Solar System.
The first solar panel in space was used in 1958, on the American satellite Vanguard 1.
It had six solar panels which each had an area of about five centimetres squared. The cells produced about one Watt of energy and were 10% efficient. Although we no longer have communications with Vanguard 1, it is still the oldest manmade object still in orbit.
There are now thousands of satellites orbiting Earth for communications, weather and many other things and most are powered by solar panels.
[Learn more: See a genuine solar-powered weather satellite on display in our Orbiting Earth gallery.]
In 1967, Soyuz 1 became the first crewed spacecraft powered by solar panels.
This was only ten years after the first artificial satellite had been launched and six years after the first human in space. Space exploration was still very new and therefore Soyuz 1 encountered many technical difficulties. One of the solar panels did not unfurl properly causing a power shortage. After 13 orbits it was decided to return the mission to Earth. Sadly, the solar panel failure was not the only problem and on the return the parachute did not deploy properly, and the Soyuz crash landed, killing astronaut Vladimir Komarov.
After this tragedy, the Soyuz programme was delayed for 18 months so that the spacecraft could be redesigned and improved. Today, more than 50 years on from Soyuz 1, this spacecraft is still a workhorse of the space industry, ferrying astronauts to and from the International Space Station. And it is still powered by a 10.6 metre solar array.
Launched in 1971 Salyut 1 was the first space station and it was powered by two double sets of solar panels. The Salyut programme paved the way for the Mir space station and the International Space Station, both of which also used solar panels.
The International Space Station has eight solar arrays, each of them 35 metres by 12 metres. These arrays can generate 120 kilowatts of electricity. While facing the Sun, about 60% of this power is used to charge the batteries so that the station can still run when it is in darkness.
[Learn more: Check out this NASA video for more on the ISS’s solar energy.]
But it is not just spacecraft orbiting the Earth that use solar panels. Solar powered missions have been sent to Mercury, Venus, Mars, the asteroid belt and even as far out as Jupiter. BepiColombo was launched in October 2018 and is en-route for the planet Mercury. It has two enormous 14 metre solar panels to power it on its seven year journey.
Juno is a spacecraft currently in orbit around Jupiter and it is the furthest mission to be powered by solar panels. It has three solar panels that measure 2.9 by 8.9 metres.
Without space exploration, it is unlikely that solar panels would have become as efficient as quickly for sustainable use down here on Earth.
So the next time you’re out basking in the warmth of our Sun, stop for a second and think about the incredible renewable power that is coming directly from our star!
About the author: Elspeth Lewis is a physicist and a member of the Education Team at the National Space Centre.