Solar power
Friday 30 October 2009
Power of the sun
The sun has produced energy for billions of years. Solar energy is generated when the sun’s rays, also known as solar radiation, reach the Earth.
This energy can be converted into other forms of energy such as heat and electricity. Only about a hundredth of a millionth of a percent of the sun’s energy ever reaches the Earth. However even his tiny fraction is enough to meet all our power needs many times over.
Solar cells
A solar cell is a device that converts the energy of sunlight directly into electricity by the photovoltaic effect. This is the most common way of generating energy from the sun.
Photovoltaic panels are made of up of layers of a silicon material that is a semiconductor. When light shines on the semiconductor an electric field is generated across the layers of the material. The electricity is then freed. The freeing of electrons leads to the production of electricity.
The stronger the sunshine, the more electricity is produced.
A photovoltaic cell is one that doesn't need direct sunlight to work - you can still generate some electricity on a cloudy day. You can also generate electricity from artificial light.
Powering up
When converted to thermal (or heat) energy, solar energy can be used to:
- Heat water — such as for homes, buildings, swimming pools etc.
- Heat spaces — such as homes, greenhouses, buildings etc.
- Run appliances from calculators to cars! A solar powered calculator only needs a small amount of electrical power to work. Most calculators work in a room with artificial light.
In some countries photovoltaic cells have been developed that will provide electrical power to pump drinking water from wells in remote villages.
Good reasons to go solar
The world isn’t getting any younger! By using solar power, you could help it out by cutting your carbon footprint by a large amount. Solar electricity is green, renewable and doesn't release any harmful carbon dioxide or other pollutants. A normal home PV system could save around 1200 kg of carbon dioxide per year - that's around 30 tonnes over its lifetime.
Solar power is also much cheaper because sunlight is free (duh!). The main cost is the installation of PV panels.
Research has shown that a home PV system can produce around 40 per cent of the electricity that a normal household uses. This could save one tonne of CO2 a year!
You can even get paid for the amount of energy your home PV produces.
Global race
The Global Green Challenge is an annual event that aims to showcase advances in hybrid, electric and low emission vehicles as well as those propelled by the sun.
This year, the 3,000 km Global Green Challenge 2009 race was won by a solar car made by Japanese students. The car has solar panels attached on the front bonnet and averages 100km an hour - just over 60 miles. Watch the team celebrating!
The race is gruelling with the course taking teams through Australia's desert heartland where temperatures can exceed 50C! The car did come across some faults, but it was nothing solar-related – it just got a flat tyre.
