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The Solar Still
Solar Stills operate on the same principles that produce rainfall.
The sun is allowed into and trapped in the Still. The high temperatures
produced destroy all pathogens. The water evaporates, and in this
process, only pure water vapor rises in the Still, only to condense
on the glass. The glass is sloped to the south, and the condensed
water runs down the glass and is collected in a trough. The water
is allowed out of the collector through silicone tubing, and is
collected in 5 gallon glass jugs. There are no moving parts in
the solar still, and only the sun's energy is required for operation.
The design of the our Solar Still began with many hours spent
researching previous designs, successes and failures. Our goal
for the Still project was to design and develop plans for a Still
which could be replicated using "off the shelf" materials.
We designed a still which is easy to replicate, using standard
building materials, of which 95% are available "off the shelf".
The exterior materials were chosen for their ability to withstand
our desert climate with minimal maintenance. The still produces
an average of 3 gallons per day in the summer months. Winter production
is expected to be 1/2 that amount. The Solar Still can utilize
a standard size patio glass replacement, 34"X76". The material
costs per still are approximately $150.
Brackish water is carefully placed inside Solar Still via an inlet
near the base of the Still. As sunlight warms the black silicone
bottom and heat is transferred to the water, the top of the water
evaporates on to the inside of the glass cover, which is tilted
toward the fresh water drain. approximately 8 square feet (of
glass cover) will distill around 1 gallon of water per day, over
five hours of full sunlight.
The most important elements of the design are the sealing of the
base with black, high temperature silicone rubber; (spread it
on with a Bondo squeegee) and creating a good seal between the
glass cover and the bottom of the box.
The Solar Basin Still
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The Still is filled each morning or evening, and the day's production
is collected at that time. The Still will continue to produce
after sundown as the water is still very hot. The Still is over
filled each day to flush out sediment. The over flow water can
be used for irrigation. The only maintenance is to clean the glass
occasionally. |
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| A Large Solar Distiller Array! |
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