What is it?
Solar energy is energy from the Sun. The Sun is a star that produces energy on a massive scale. Nuclear fusion reactions in its core turn 4.3 million tonnes of hydrogen into energy every second. This energy eventually radiates into space, in all directions. Travelling at the speed of light, a small fraction of it reaches the Earth about eight minutes after it leaves the Sun.
How is it used?
There are two ways to use solar energy:
Solar photovoltaic (PV) cells convert light energy directly into electricity. They can be arranged in panels and fitted to roofs and the sides of buildings.
Active solar water heating is an easy source of hot water. Fluid inside a black panel, tilted to face the Sun, heats up and is then circulated to the hot water tank inside the house. There, the heat is transferred to the household water system for use in the home.
Where can you find it?
Large-scale solar energy plants are only cost effective in countries where there is lots of sunshine.
Advantages and disadvantages of using solar energy to generate electricity
• Solar energy is renewable and the Sun’s heat and light are free
• Solar energy can be used to generate electricity in remote places where other electricity supplies are hard to come by
• It does not produce any carbon dioxide, which contributes to the greenhouse effect
• Energy is usually generated at or near to the location it will be used. This keeps transmission and distribution costs to an absolute minimum
• PV cells do not work so well when it is cloudy and do not work at night
• The UK is not a very sunny country! Solar power works better in hot places, so its use is therefore limited
How many systems in the UK?
There are over 100,000 small solar heating systems in the UK, but very few houses have solar PV cells.
How much does it cost to produce electricity?
It costs around £6,000 to install a solar PV system in a typical house in the UK. The active water heating costs £2,500-£4,000. On average it costs less than 10p/kWh.
What is the carbon cost?
Generating electricity with solar PV panels does not produce any carbon dioxide.
Our climate (in the UK) is not really suitable for it to become a major source, but it could still play a role in water heating systems and electricity generation for the home.
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