Solar Power is energy from the Sun

Introduction  How it works   More details  Advantages   Disadvantages  Is it renewable?

Introduction

We've used the Sun for drying clothes and food for thousands of years, but only recently have we been able to use it for generating power.

The Sun is 150 million kilometres away, and amazingly powerful. Just the tiny fraction of the Sun's energy that hits the Earth (around a hundredth of a millionth of a percent) is enough to meet all our power needs many times over - if only we could harness it properly.

How it works

There are three main ways that we use the Sun's energy:-

1. Solar Cells (really called "photovoltaic" or "photoelectric" cells) that convert light directly into electricity.
   
   This was originally developed in order to provide electricity for satellites, but these days many of us own calculators powered by solar cells.
   
   
   In a sunny climate, you can get enough power to run a 100W light bulb from just one square metre of solar panel.
   
   
   
   
2. Solar water heating, where heat from the Sun is used to heat water in glass panels on your roof.
   
   This means you don't need to use so much gas or electricity to heat your water at home.
   
   
   
   
   
   Water is pumped through pipes in the panel. The pipes are painted black, so they get hot when the Sun shines on them. This helps out your central heating system, and cuts your fuel bills. However, in the UK you must remember to drain the water out to stop the panels freezing in the winter.
   
   
   Solar heating is worthwhile in places like California and Australia, where you get lots of sunshine.
   
   
   
   
3. Solar Furnaces use a huge array of mirrors to concentrate the Sun's energy into a small space and produce very high temperatures.
   
   There's one at Odellio, in France, used for scientific experiments.
   
   It can achieve temperatures up to 33,000 degrees Celsius.

More details

Solar cells provide the energy to run satellites that oribt the Earth. These give us satellite TV, telephones, navigation, weather forecasting, the internet and all manner of other facilities.

In California, the Solar One power station uses the Sun's heat to make steam, and drive a generator to make electricity. The station looks a little like the Odellio solar furnace (see picture above), except that the mirrors are arranged in semi-circles around the "power tower".

As the Sun moves across the sky, the mirrors turn to keep the rays focussed on the tower, where oil is heated to 3,000 degress Celsius, The heat from the oil is used to generate steam, which then drives a turbine, which in turn drives a generator capable of providing 10kW of electrical power.

Solar One was very expensive to build, but as fossil fuels run out and become more expensive, solar power stations may become a better option.

Advantages

• Solar energy is free - it needs no fuel and produces no waste or pollution.
• In sunny countries, solar power can be used where there is no easy way to get electricity to a remote place.

Disadvantages

• Doesn't work at night.
• Expensive to build solar power stations.
• Can be unreliable unless you're in a very sunny climate. In the United Kingdom, solar power isn't much use, as you need a very large area of solar panels to get a decent amount of power.

Is it renewable?

Solar power is renewable. The Sun will keep on shining anyway, so it makes sense to use it.

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