Energy from the Sun (Cambridge O Level Physics)

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Dan MG

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Energy from the Sun

  • Most of our energy resources on the Earth come from the Sun:
    • The Sun heats up the atmosphere, creating wind and producing waves
    • Water evaporated by the Sun falls as rain, filling up reservoirs
    • Plants grown using sunlight form the basis for fuels – both biofuels and fossil fuels
  • Some forms of energy, however, do not come from the Sun, these include:
    • Geothermal – this comes from heat produced in the Earth’s core
    • Nuclear – this comes from elements which make up a small proportion of the Earth’s crust
    • Tidal – this comes (mainly) from the gravitational attraction of the Moon

Solar Radiation

  • The energy from the Sun that falls on the Earth is transferred by radiation 
    • This is mostly visible light and infrared radiation
  • The amount of energy transferred from the Sun to the Earth each hour is equal to the energy use of the world in one year
  • Therefore, scientists are working hard to find methods of harnessing this energy
    • Solar energy has a low energy density, which means large collecting devices are required 
    • Collecting solar energy is expensive (due to the equipment required) and inefficient

Solar Cells

  • Solar cells transfer energy from sunlight electrically producing a current, and therefore generating electricity 
    • Solar cells, sometimes called photovoltaic cells, are made of semiconducting materials
    • A number of cells connected together can supply electricity to homes, small-scale businesses, communication devices and satellites
    • Energy generated from solar cells can be stored in batteries for later use

Field of Solar Cells

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Solar cells use energy from sunlight to produce electricity

Solar Panels

  • Solar panels transfer energy from sunlight to the thermal store of the solar panels
    • This can be used to heat water in pipes for domestic water supplies 
    • This can reduce the cost of producing hot water since it is heated partially by the solar panel

Function of a Solar Panel

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Solar panels use energy from sunlight to heat water

Solar Furnaces

  • Solar furnaces consist of large curved mirrors that focus the Sun's rays onto a small area
  • These can be used to heat water to generate steam which can turn turbines and generate electricity in a power station
    • Water is stored in a water tank and pumped through small pipes running through the solar panel
    • Infrared radiation from the Sun heats the water in the pipes as it flows through them
    • The water returns to the tank at a higher temperature
  • Water may still need to be heated further to reach the desired temperature (e.g. for a shower)

Advantages of Solar Energy

  • Solar energy is a renewable resource
  • In many places on Earth, sunlight is a reliable energy resource (i.e. places where the Sun shines most of the time)
  • Solar farms produce no greenhouse gases or pollution
  • Solar energy can be generated in remote places and in individual homes
  • Solar panels are cheaper to produce and maintain than other energy sources

Disadvantages of Solar Energy

  • Solar farms need to be large scale to produce large amounts of electricity and this requires vast areas of land
  • People often don't like the appearance of large solar farms, this is known as visual pollution
  • In many places on Earth, sunlight is not a reliable energy resource (i.e. places where there is a lot of cloud cover)

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Dan MG

Author: Dan MG

Expertise: Physics

Dan graduated with a First-class Masters degree in Physics at Durham University, specialising in cell membrane biophysics. After being awarded an Institute of Physics Teacher Training Scholarship, Dan taught physics in secondary schools in the North of England before moving to SME. Here, he carries on his passion for writing enjoyable physics questions and helping young people to love physics.