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.)
HOW IT WORKS
Although only a small set up, your Solar Water HH Heater demonstrates the working principle of most
domestic solar water heaters. The Solar Water Heater hea^ats the water using energy from the Sun. The Sun
gives out energy in the form of heat and light. The energy yjy travels through space in rays and some of it hits
the Earth. The heat and light that hits the solar panel is as absorbed by the black surface of the panel. When
the water is cooler than the panel, heat flows into the wasvater, making it warmer. Wa rim water is less dense
than cool water, and so the warmed water rises up the tit tube into the water tank. Cool water flows from the
tank to replace it. This circulation of water continues uu until all the water is at the same temperature as the
panel. In a real solar water heater, the heated water isaiis stored in an insulated storage tank which keeps the
water warm until it is used, even if that is at night, hd hours after the Sun has gone; down.
TROUBLESHOOTING
If the water in the water tank does not heat up: q p
:
•
The sunshine may not be strong enough. You um may have to wait until a hotter day.
•
The wind may be cooling the heater. Either s> • shield the heater with cardboard boxes or wait until a less
windy day.
•
On a cold day, the heat loss from the storage t stank to the air could be larger than the heat gain from solar
panel, and so the water may not heat up. You co can try covering the water storage tank with a small plastic
bag that will help to insulate the bottle. Tie thtriihe opening loosely around the bottle's neck so that you can
easily remove it to feel the water temperature. .9e. You can also cover the expcosed plastic tubes with plastic
food wrap to insulate them.
•
Make sure that the solar panel is facing the Si2 Sun all the time. Check it each hour as the Sun moves
across the sky. Also make sure no shadows fall on the 9ne panel.
•
Check that there are no bubbles in the tubes2ss. If there are, gently shake oir tap the tubes to dislodge
them.
Fun Facts
•
The solar panel is black because black materhsrials are good at absorbing heat. A white panel would reflect
the heat and light away.
•
Your Solar Water Heater works in the same 9e way as a proper domestic solar water heater. A domestic
system has a solar panel mounted on a roof witiwith 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 i ft is a renewable source of energy because the Sun will
always keep shining.
•
The world's largest solar thermal power statitstion is Kramer Junction in California. It provides 150 MW of
energy.
•
In remote areas of the world, solar energy is u
8
used to heat water to pasteuirize the water. This makes dirty
water safe to drink.
•
Solar energy provides only about 1% of the vw
\
world's energy needs.
•
Less than a billionth of the energy the Sun gi§ gives out hits the Earth. Evern so, this is ten thousand times
as much as all the energy we use.
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,
making sure that the tubes lead out through the
opening slot of the connector.
8.
Now stick the 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.
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.
Summary of Contents for Solar Science
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