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Solar air conditioning &
House
Space Cooling
Solar air
conditioning: cooling your house with solar energy?
Until now the applications of solar energy are
mostly limited to heating purposes and to PV solar electricity,
and it may sound strange to use the sun energy in house cooling
purposes. And yet it’s possible.
Solar home space cooling systems are part of the
Thermally Activated Cooling Systems (TACS), and for some
enthusiasts of solar energy, they are an
environmentally-friendly technique with a promising future.
Some gigantic facilities as the Los Angeles
Audubon Nature Center - a 5,026-square-foot facility devoted to
enjoyment and education – has a fully solar-powered air
conditioning system (heating and also cooling).
Solar air cooling systems:
possible but expensive
Today’s solar air conditioning systems aren’t competitive,
mainly in stand-alone applications. Solar cooling is rarely used
because of the high initial costs of the system implementation.
Only when combined with solar home water heaters
and space heating systems they may become more competitive. Most
stand-alone solar cooling systems are quite expensive
investments: solutions of $4000 - $8000 per ton are very common.
Implementing a solar house
cooling solution
Once solar cooling systems demand expensive
investments, a possibility is to develop combined
air conditioning systems (dual systems) using the same basic
equipment/collectors. This solution - serving more than just the
cooling needs – allows the use of the installed equipment in the
parts of the year when cooling is not required.
Manufacturers and suppliers of
solar
air conditioning
There isn’t a specific offer of solar space
cooling equipment on a national basis, and there aren’t local
suppliers either, contrasting with other solar equipment… Solar
home space cooling solutions have to be studied and implemented
in conjunction with solar heating technicians and experts on
common gas cooling systems.
A partial solution
Most solar air conditioning solar systems solutions are sized to provide
40% - 70% of house cooling requirements (the remainder are
usually fueled by natural gas or other means).
Technologies available
Technologies available for solar-driven cooling
include 1) advanced absorption systems and 2) desiccant cooling
systems.
Solar absorption technology
Absorption technology demand high temperatures
and collectors capable of producing them: evacuated-tube and
concentrating type solar collectors… The energy from these solar
collectors is used to separate a tank liquid mixture that
includes an absorbent (lithium bromide salt, for instance) and a
refrigerant fluid (often the water). The refrigerant (water
vapor) is then condensed and eventually evaporated to produce
the desired cooling effect.
In the Audubon Nature Center case, cited above,
the thermal energy from the solar collectors is driven to a
1,200-gallon insulated high-temperature hot water storage tank.
When the stored hot water reaches the right temperature (180
degrees F…), it is pumped through a generator into a chiller
containing a lithium bromide salt (the absorbent) which yields
water vapor (the refrigerant) that subsequently is condensed to
produce chilled water. In its terminal phase, the system use fan
coil units to drive the indoor building air across the coils
containing the chilled water, causing its cooling.
Solar desiccant technology
Solar desiccant technologies use… desiccants -
substances like silica gel, calcium sulfate, etc. to absorb the
air humidity and to cool it. Desiccants are commonly solids, but
may also be liquids. Both technologies are very similar in their
implementation.
In the case of the solid desiccant system, as the
air passes through the desiccant (usually located on a wheel
rotating into the air stream going into the house rooms) the
moisture is removed from the air, causing the humidity level and
the temperature of the air to drop. At the same time the thermal
energy from the solar collectors is used to dry the desiccant,
driving off the absorbed water (as it rotates out of the air
stream).
Heat pumps and other alternatives
for solar air conditioning and cooling
Since solar cooling systems demand expensive
investments and aren't a well established technology with a wide
offer, you should consider other environmentally-friendly
options, namely:
- a combination of a
correct insulation
with energy-efficient
doors and windows,
shading and
ventilation; this
combination will keep homes cool with a minimal use of energy (except
in the hottest climates, where ventilation is usually a bad
option).
- ground (or
geothermal) heat pumps: they are an excellent solution for
home heating but also for home cooling.
- ventilation (though not in hot
humid climates):
natural ventilation and a
good fan system (combined
with approaches as insulation) will reduce dramatically the need
to use air conditioning.
- evaporative coolers (also called swamp coolers):
in dry climates,
this very cheap alternative produce very good cooling results at
very low low costs. Evaporative cooler are cooling devices in
which a blower forces air through over water-saturated pads,
cooling it and pushing warmer air out through windows.
See also:
Basics of
solar systems
Domestic Solar Hot Water Systems
Solar Electricity: Photovoltaic PV Systems
Solar Space Heating & Indoor
House Air Heating
Pros and Cons of Solar
Energy Panels
Costs and payback of
Solar Energy
Solar Panels Technology
Quotes and the
buying process
Market and Prices of Solar Hot
Water Systems
Market and Prices of Solar PV
Electricity
Manufacturers of Solar
Power Systems
Back to top Questions to Dealers and Installers
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