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that the water can run into the tube. Make sure the water completely covers
both pieces of tubing. Gently shake or tap the tube and panel to dislodge any
air bubbles. Check thoroughly that all bubbles are gone before moving to the
next step.
7. Now set up your Solar Water Heater. Insert the storage tank to the upper part
of the connector which has already been install on the larger bottle,
OPERATION
1. You need a sunny day to try out your
Solar Water Heater. The sunshine will be at
its strongest in the middle of the day (i.e.
between 10 a.m. and 2 p.m.). Place the Solar
Water Heater outside in the sunshine. Turn
and tilt the solar panel so that it faces
directly into the Sun. (If you are using a tall
bottle for stand, so that the solar panel
dangles in the mid air, support the panel
with a cardboard strip placed between the
panel's back and the bottle stand.)
2. Every fifteen minutes feel the water tank. The water inside should
gradually get warmer and warmer. On a sunny day the water will reach a
temperature up to 40°C (104°F) within a few hours. The temperature indicator
will change to a yellow colour above this temperature. (Most domestic solar
water heaters heat water to 40 to 50°C (104 to 122°F) and store it for use
afterwards.)
Remarks: If you would like to operate your Solar Water Heater indoors or at a
school science fair, you can use a desk lamp with an incandescent light bulb as a
source of heat. Do not use an energy-efficient fluorescent lamp as it will not
output enough heat. Adjust the lamp so that it is close to the panel and shining
straight at it. The simulated "sun" will heat up the water in the system.
making sure that the tubes lead out through the
opening slot of the connector.
8. Now stick the
k
40°C (104°F) thermo indicator onto the smaller
bottle surface, just next to the water level.
9. Fix the top edge of solar panel to the bottle stand
with an adhesive tape. Congratulations. Your Solar
Water Heater is ready to go.
HOW IT WORKS
Although only a small set up, your Solar Water Heater demonstrates the working principle of most domestic
solar water heaters. The Solar Water Heater heats the water using energy from the Sun. The Sun gives out
energy in the form of heat and light. The energy travels through space in rays and some of it hits the Earth. The
heat and light that hits the solar panel is absorbed by the black surface of the panel. When the water is cooler
than the panel, heat flows into the water, making it warmer. Warm water is less dense than cool water, and so
the warmed water rises up the tube into the water tank. Cool water flows from the tank to replace it. This
circulation of water continues until all the water is at the same temperature as the panel. In a real solar water
heater, the heated water is stored in an insulated storage tank which keeps the water warm until it is used,
even if that is at night, hours after the Sun has gone down.
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TROUBLE SHOOTING
If the water in the water tank does not heat up-.
• The sunshine may not be strong enough. You may have to wait until a hotter day.
• The wind may be cooling the heater. Either shield the heater with cardboard boxes or wait until a less windy
day.
• On a cold day, the heat loss from the storage tank to the air cou Id be larger than the heat gain from solar
panel, and so the water may not heat up. You can try covering the water storage tank with a small plastic bag
that will help to insulate the bottle. Tie the opening loosely around the bottle's neck so that you can easily
remove it to feel the water temperature. You can also cover the exposed plastic tubes with plastic food wrap to
insulate them.
• Make sure thatthe solar panel is facing the Sun all the time. Check it each hour as the Sun moves across the
sky. Also make sure no shadows fall on the panel.
• Check that there are no bubbles in the tubes. If there are, gently shake or tap the tubes to dislodge them.
FUN FACTS
• The solar panel is black because black materials are good at absorbing heat. A white panel would reflect the
heat and light away.
• Your Solar Water Heater works in the same way as a proper domestic solar water heater. A domestic system
has a solar panel mounted on a roof with pipes running through it. Heated water from the panel is stored in a
water tank indoors.
• Energy from the Sun is called solar energy. It is a renewable source of energy beca use the Sun will a Iways
keep shining.
• The world's largest solar thermal power station is Kramer Junction in California. It provides 150 MW of
energy.
• In remote areas of the world, solar energy is used to heat water to pasteurize the water. This makes dirty
water safe to drink.
• Solar energy provides only about 1% of the world's energy needs.
• Less than a billionth of the energy the Sun gives out hits the Earth. Even so, this is ten thousand times as
much as all the energy we use.
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- Ir HiO^ii
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