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Solar Powered
Attic Fan
Brent Houghton
Dominic Gayle
Alejandro Osorio
Faculty Advisor:
Dr. Seyad Ebrahim Beladi
Household Attic
Temperatures in attics can reach up to 140 Degrees Fahrenheit
Infiltrations/Air leakage into household
Results in increased strain on A/C
Turbines and Fans
Visually Unappealing
Provide Little Ventilation
Power Consumption
Current Market Weaknesses
Most current models do not implement a rechargeable battery.
Under powered and overestimated in terms of performance.
Geographic orientation on roof is confined to solar angles.
General Design
Major Components
 4 X Sunforce 50022 5 Watt Trickle Charger configured in parallel
 Current: 325 mAmps @ 15 V
 Diode to prevent reverse discharge from battery
Pulse Width Modulator to govern
RPM’s
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An pulse width modulator, or PWM, is an electronic circuit which is primarily used to vary an
electric motor's rotational speed and direction
it may serve as a dynamic brake as well.
ESCs are often used on electrically powered radio controlled models, with the variety most
often used for brushless motors essentially providing an electronically-generated three phase
electric power low voltage source of energy for the motor.
•
trol.
Sunforce 7 Amp Solar Charge
Controller
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Protects battery from overcharge/discharge.
Handles up to 7 Amps of array current.
Maintains 12 Volt battery in a fully charged state.
Powersonic PS-12350-NB Deep Cycle
Battery
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12 Volt/35 Amp Hour Sealed Lead Acid Battery
Deep Cycle Battery intended for high charge/discharge rate.
Wide operating temperatures ideal for attic conditions.
Valve regulated, spill proof construction allows for safe operation in any
position.
Procomp 14” Pusher/Puller Fan
• 12 Volt DC high performance reversible electric cooling fan.
• Blades and wire polarity may be reversed for pushing/pulling
option.
• 2000 CFM rating.
GadgetZone CN101 Digital
Programmable Timer
• Programmable for 17 ON/OFF events per day.
• Dual installation allows for air outake/intake.
• Lithium battery to prevent short during power
outage.
Fundamental Design
• 4 solar panels charge battery daily.
• Allows for continuous usage during night and day.
• CFM/s may be adjusted due to power budget.
Fundamental Design: Housing
Structure
Fundamental Design: Automatic
Control Panel
Potential Problems
• To generate enough current to sufficiently charge
battery to power motor driven fan?
• Heat from attic can be a strain on battery
• Higher cost than conventional solar fans, yet
more advanced
• Sleek design with regard to marketing
Literature Survey
 Attic Fans.
 Solar powered attic fans.
 Photovoltaic Cells
Attic Fans
 Used in warmer and cold climates.
 Summer months temperature can reach 160 F.
 Moisture and cold can lead to mildew growth
in the attic as well on winter season.
Moisture on Attics
http://www.ussunlight.com/images
/product_images/products_general/
winter_apv.jpg
http://www.bluepointenvironmental.com/
wp-content/uploads/2012/01/atticcontamination1.jpg
Summer Season on Attics
http://poweredbydaylight.com/wpcontent/uploads/2011/03/attic-heat-300x300.jpg
Solar Attic Fans
 Solar attic fans are available for general consumer on retail stores.
 No efficient product limited to a power delivered for a photovoltaic cell.
 Generally Solar Attic are not very aesthetically pleasing to homeowners.
Photovoltaic Cells
http://www.ecoplanetenergy.com/wp-content/uploads/2012/03/solar-PV-energy-origins.gif
Environmental Impacts
 Most components pose no threat.
 Battery is rechargeable.
 Runs on direct current.
 Ideal for any suitable
geographical locations
In which a need arises.
 Generate large amounts of electricity without producing any
pollution to the ambient surroundings or adding to global warming.
 Photovoltaic cells can have working lives of up to 30 years
 Manufacturing companies must employ proper protocols to prevent
exposure of these chemicals to the environment.
http://grist.files.wordpress.com/2013/04/s
olar-panels-homepage.jpg
http://www.think-solar-power.com/PhotovoltaicSolar-Power.html
 Low impact to the ambient on manufacturing process.
 Optimize equipment use and extend operation hours.
http://www.dbpow.com/
http://www.sunforceproducts.com/
POWER SONIC
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96% of all lead-acid batteries are recycled.
Almost any retailer collects used batteries for recycling (State laws)
They send the plastic to a reprocessor for manufacture into new plastic
products.
lead-acid battery contains 60 to 80 percent recycled lead and plastic.

http://www.batteryweb.com/power-sonic-corporation.cfm
http://ecobatgroup.com/ecobat/rp/
 Housing, blades and mounting brackets are made from
plastic.
 Cooper coil winding.
 Indirectly Powered by Solar Energy.
http://blog.heliumware.com/wpcontent/uploads/2011/01/IMG_0111.jpg
.
http://thumbs2.ebaystatic.com/d/l225/m/mQzgm6
y2pubd8L75antwOYg.jpg
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ASHRAE – American Society of Heating, Refrigerating, and Air-Conditioning
Engineers.

ASCE – American Society of Civil Engineers.
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ASM - American Society for Metals. (6061)
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ASME - American Society for Mechanical Engineers.

IEEE - Institute of Electrical and Electronics Engineers.

ANSI – American National Standards Institute.
• Tropical storms and hurricanes are devastating and as such steps must
be considered in design.
Category
Wind Speed (m/s)
Wind Loading
(N)
Wind Loading
(lbf)
Storm
32
165
37
1
42
285
64
2
49
388
87
3
58
544
122
4
70
792
178
• Wind Loading = 0.5ρv2CdA
• Cd ranges from 1.2 - 1.65. Use 1.65 for safety.
• Analysis conducted as if force acted perpendicularly to housing.
• Initial model used to conduct analysis.
• Due to software limitations, certain concessions were necessary.
• Greatest stresses were concentrated in the bends of the housing.
• Safety factor of 1.2 under tropical storm loading.
• 49 MPa maximum stresses within the bended regions.
• Safety factor of less than 1.
• Recommended fastener : #8 X 2” screw, self-tapping and galvanized –
ASTM standard.
• Length will vary depending on roof thickness.
• 650 screws for $34.55.
• Housing failure more significant than fasteners.
• Poor aerodynamic structure results in tremendous wind loading.
• Remove attic fan for conditions greater than tropical storm loading.
• Simulation conducted with hemispherical dome.
• Diminished area results in max velocity of 4.4 m/s (13 fps).
• Highest pressure experienced around outlet regions of housing.
Outdoor
Temperature
(°F)
Indoor
Temperature
(°F)
Attic
Temperature
Before
Activation
Cycles (°F)
Attic
Temperature
After
Activation
Cycles (°F)
Attic
Temperature
Difference (°F)
85
78.0
106.3
92.4
13.9
82
79.1
102.5
85.6
16.9
85
78.0
107.9
92.4
15.5
• Based on fan drawing 1.8 Amps @ 600 CFM for 90 second
interval (expulsion cycle).
• Resting interval for 60 seconds (no fan activity).
• Based on fan drawing 1.8 Amps @ 200 CFM for 60 second
interval (intake cycle).
é
W ù
ê CFM * DT *1.08 AC tons *1300 AC tons ú
hours of operation*ê
ú - Fan Power
12000
ê
ú
ë
û
Energy Savings =
W
1000
kWh
• Estimate of 4.31 kWh/day savings.
• Investigate a real-world global issue and use engineering knowledge to address it.
• Gain valuable experience and insight into manufacturing process.
• Importance of team work i.e. goal specifications, task delegation, conflict resolution
,etc.
Questions?
Comments?