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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
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.
In fact, every minute, enough energy arrives at
the Earth to meet our demands for a whole year - if only we could
harness it properly.
Currently in the UK there are grants available to
help you install solar power in your home.
to see examples of solar products.
How it works:
There are three main ways
that we use the Sun's energy:-
(really called "photovoltaic", "PV" or "photoelectric"
cells) that convert light directly into electricity.
In a sunny climate, you can get enough power
to run a 100W light bulb from just one square metre of solar panel.
This was originally developed in order to provide
electricity for satellites, but these days many of us own calculators
powered by solar cells.
People are increasingly installing PV panels on
their roofs. This costs thousands of pounds, but if you have a
south-facing roof it can help with your electricity bills quite
a bit, and the government pays you for any extra
energy you produce and feed back into the National Grid (called
the "feed-in tariff").
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 hotter when the Sun shines
on them. The water is pumped in at the bottom so that convection
helps the flow of hot water out of the top.
This helps out your central heating system, and cuts your fuel
bills. However, with the basic type of panel shown in the diagram
you must drain the water out to stop the panels freezing in the
winter. Some manufacturers have systems that do this automatically.
Solar water heating is easily worthwhile in places
like California and Australia, where you get lots of sunshine.
Mind you, as technology improves it's becoming worthwhile in the
Here's a more
advanced type of solar water heating panel.
The suppliers claim that in the UK it can supply 90% of a typical
home's hot water needs from April to November.
This "Thermomax" panel is made of a set
of glass tubes. Each contains a metal plate with a blue-ish coating
to help it absorb solar energy from IR to UV, so that even in
diffuse sunlight you get a decent output. The air has been removed
from the glass tubes to reduce heat loss, rather like a thermos
Up the back of the metal plate is a "heat pipe",
which looks like a copper rod but contains a liquid that transfers
heat very quickly to the top of the glass tube. A water pipe runs
across the top of the whole thing and picks up the heat from the
Find out more at www.solarsense-uk.com/thermomax.php
The main way that a conventional gas "combination boiler"
continually wastes energy is by replenishing stored water as
soon as the volume or temperature decreases.
With solar powered boilers, this is instead
fuelled by the solar power collected through panels on the roof
of your home.
The power collected through the solar tiles is used to fuel
and therefore heat a separate water cylinder, thus saving energy
throughout the course of every day.
Another smaller tank, still powered by gas, is provided with
most solar boiler installations as a backup.
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 Odeillo, in France, used for scientific
It can achieve temperatures up to 3,000 degrees Celsius.
out more from wikipedia...
Solar furnaces are basically huge "solar cookers".
A solar cooker can be used in hot countries to cook food. This
one is in the UK, making tea and coffee, although it does take
a long time!
Solar cells provide the energy to run satellites
that orbit the Earth. These give us satellite TV, telephones, navigation,
weather forecasting, the internet and all manner of other facilities.
The graphic shows a GPS satellite. A satellite navigation receiver
in a car gets signals from a whole host of these and works out it's
Find out more about GPS navigation at howstuffworks.com
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 Odeillo solar furnace , except that the mirrors are arranged
in -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.
There are solar
powered electric boats on Coniston Water
in the Lake District, England.
Video clip: How PV solar
panels are made
| One idea that is being considered is to build
The idea is very simple - you
build a big greenhouse, which is warmed by the Sun. In the middle
of the greenhouse you put a very tall tower.
The hot air from the greenhouse will
rise up this tower, fast - and can drive turbines along the way.
This could generate significant amounts
of power, especially in countries where there is a lot of sunshine
and a lot of room, such as Australia.
- 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.
- Handy for low-power uses such as solar powered
garden lights and battery chargers, or for helping your home energy
- Doesn't work at night.
- Very expensive to build solar power stations, although
the cost is coming down as technology improves. In the meantime, solar
cells cost a great deal compared to the amount of electricity they'll
produce in their lifetime.
- Can be unreliable unless you're in a very sunny climate.
In the United Kingdom, solar power isn't much use for high-power applications,
as you need a large area of solar panels to get a decent amount of
power. However, technology has now reached the point where it can
make a big difference to your home fuel bills..
Is it renewable?
power is renewable.
The Sun will keep on shining anyway, so it makes sense to use it.