Thomas Buck, Kyle Garner, Alexandra Jung, Quinn McGehan, Mark Sakaguchi,

and Scott Taylor

Team Solkraft

Final Presentation 11/30/2010

Mission Overview• Objective

– To determine the effect of near space conditions on solar cell output.• Temperature, light intensity, and altitude.

– Expect to prove that there is a relationship between the variables above and the output of two different types of cells.

– Determine effectiveness of using solar cells on stratospheric platforms.• Hypothesis

– The monocrystalline cells will outperform the polycrystalline cells, while both cells will perform better in near space than on the ground.

Mission Design: How?• Experiment will incorporate three main categories

– Photodiodes: Detect light intensity to determine the “amount” of sunlight hitting the panels

– Thermistors: On each face to detect temperatures effect on output.

– Solar cells: Two different types to determine which one is most efficient

• All three components will be flowed into multiplexer– Multiplexer will deliver multiple logs per minute– Arduino will log results to MicroSD card to be uploaded

into Matlab/Excel

Mission Design

Monocrystalline Cell

Polycrystalline Cell

HOBO External Temp Sensor

HOBO (Velcroed to wall of Balloonsat)

Camera

Arduino (Velcroed to wall of Balloonsat)

Heater

Multiplexer (Later moved to fit directly on top of Arduino)

Photodiode

Thermistor

Switches

Mission Design 3 9V

Batteries Switch Heater

Batteries Switch Camera 2 GB Memory Card

Multi-plexer

Thermisters

Photodiodes Polycrystalline Solar Cells

Monocrystalline Solar Cells

Batteries Switch Arduino 328

2GB Micro SD Card

HOBOPower

Switch

Provided Hardware

Sensors

Solar Cells

Differences • Changed some of the layout of the

BalloonSat so that there would be more room.– Arduino moved to sidewall instead of

on bottom– Heater moved more toward center of

satellite– Batteries laid flat against bottom

• Originally started with just one type of solar cell.

• Originally did not have multiplexer in the design, but would have needed one with what we were planning on doing in the beginning.

90 mm220 mm

110 mm

128 mm

Results• Hypothesis:

– (1)The monocrystalline cells will outperform the polycrystalline cells– (2) Both cells will perform better in near space than on the ground

• Results:– Both portions of our hypothesis proved to be true based on our

experiment– Monocrystalline:

• Average output of 0.526V during flight; .490 V on ground– Polycrystalline

• Average output of 0.458 V during flight; .437 V on ground

0 50 100 150 2000

0.1

0.2

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0.5

0.6

0.7

0.8 -50

-40

-30

-20

-10

0

10

20

30

Monocrystalline vs. TemperatureVoltage Output Temp

Time (min)

Out

put (

V)

Tem

pera

ture

(°C)

Alti-tude

Burst

Landing

0 50 100 150 2000

0.1

0.2

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0.5

0.6

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0.8 -50

-40

-30

-20

-10

0

10

20

30

Polycrystalline vs. TemperatureVoltage Output Temp

Time (min)

Out

put (

V)

Tem

pera

ture

(°C)

Alti-tude

Burst

Landing

BurstLanding

0 20 40 60 80 100 120 140 160 180 2000

0.1

0.2

0.3

0.4

0.5

0.6 0

5

10

15

20

25

30

35

40

Monocrystalline GroundMonocrystalline Temperature

Time (min)

Out

put (

V)

Tem

pera

ture

(cel

sius)

0 20 40 60 80 100 120 140 160 180 2000

0.1

0.2

0.3

0.4

0.5

0.6 0

5

10

15

20

25

30

35

40

Polycrystalline GroundPolycrystalline Monocrystalline

Time (min)

Out

put (

V)

Tem

pera

ture

(cel

sius)

Temperature

0 20 40 60 80 100 120 140 160 180 2000

0.1

0.2

0.3

0.4

0.5

0.6

Ground ComparisonMonocrystalline Polycrystalline

Time (min)

Out

put (

V)

0 50 100 150 200 2500

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0.5

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0.7

0.8

Photodiode Voltage Output

Time (Minutes)

Volta

ge R

eadi

ng

Turned

BalloonSat

Turned

BalloonSat

Turned

BalloonSat

10 15 20 25 30 35 400

0.1

0.2

0.3

0.4

0.5

0.6

Control Experiment-Ground Voltage Output (One Solar Panel)

Temperature (Degrees C)

Volta

ge

Upper line is when side was directly in the sun. Lower line is when this side was away from the sun.

Failure Analysis– Inside of BalloonSat dropped below -10 °C

• Inadequate insulation around camera• Happened immediately following burst

– One thermistor failure• Wiring broke loose during flight• Re-tested and works

Failure Analysis

-30

-20

-10

0

10

20

30

Internal Temperature (°C) from HOBO

Time

Burst

Conclusions• Solar cells perform better in a near-space environment than on the ground• As temperatures decrease, solar cell efficiency increases• As altitude increases, solar cell efficiency increases (could be the effect of

temperature)• Temperature effects solar cell output more than altitude, therefore, the

effect of the atmosphere on ground based solar cells is minimal• Monocrystalline cells are more efficient than polycrystalline cells• The use of a stratospheric platform in the tropopause at the coldest point

would prove to be optimal for voltage output

Lessons Learned– Organization

• Did not plan out how the wires were laid out• As a result it would have been much harder to

repair or change– Teamwork

• Working as a team is important• It is important to split up the work evenly

– Self-Discovery• Finding answers is difficult• Start looking for help early

Ready to Fly• Problems

– Internal temperature dropped below -10– Faulty thermistor

• How they were fixed– Extra insulation around camera hole, and insulation between HOBO

and foamcore.– Corrected a solder joint in the wire where it had come undone.

• Things to do before flight– New Batteries– Set HOBO to record

RFP RequirementsRequirement Results

Design shall have additional experiment(s) that collects science data and teams must analyze this data.

BalloonSat conducted solar cell experiment and successfully collected data.

After flight, BalloonSat shall be turned in working and ready to fly again. BalloonSat will be turned in ready to fly.

Internal temperature of the BalloonSat shall remain above -10˚C during the flight.

Internal Temperature dropped to -25 Celsius due to insulation problem.

Total weight shall not exceed 850 grams. Total weight was 793 grams.

Design for allow for HOBO, temperature cable, camera, heater, and should be constructed out of foam core. Contact information and a US flag should be placed on the outside of the BalloonSat.

Successful.

No one shall get hurt. Luckily, no one was harmed in the making of this BalloonSat.

RFP Requirements (cont.)Requirement Results

All hardware is the property of the Gateway to Space program and must be returned in working order end of the semester.

All hardware is in working order.

All parts shall be ordered and paid by Chris Koehler’s CU Mastercard by appointment to minimize reimbursement paperwork. All teams shall keep detailed budgets on every purchase and receipts shall be turned in within 48 hours of purchase with team name written on the receipt along with a copy of the Gateway order form (HW 04).

All parts were paid for by Chris except for out of pocket expenses covered by the team.

Have fun and be creative. Success!

Absolutely nothing alive will be permitted as payloads, with the exception of yellow jackets, mosquitoes, fire ants, earwigs, roaches, or anything you would squish if you found it in your bed.

No animals were harmed in the name of our experiment.

Completion of final report (extra credit if team video is included) Completed.

Name Purpose Dimensions (mm) Mass (g) Cost Where We get it

Canon A5701S Camera Take Pictures 45x75x90 220 Provided Space Grant

HOBO Datalogger Measure/record temperature and humidity

68x48x19 30 Provided Space Grant

Monocrystalline Solar Panels (6: 4 used, 2 extra)

Experiment 42x41x6 6 (each) $4.95 (each) Edmund’s Scientific

Polycrystalline Solar Panels (6)

Experiment 57x29x6 5 (each) $1.49 (each) The Electronic Goldmine

Photodiodes (6) Measure light intensity 4 $.40 West Florida Components

Heater Maintain internal temperature 10x50x50 100 Provided Space Grant

9V Batteries (4+extra for tests)

Provide Power 48x25x15 34 (each)

$10.00 King Soopers

Arduino DuemilanoveMicrocontroller

Record voltage readings from solar cells and light intensity readings from photodiodes

69x53 40 $59.95 Sparkfun electronics

9V to barrel jack adapter Power Microcontroller 10 $2.95 Sparkfun

Switches Turn on/off electronics Provided Spacegrant/with Arduino

Connecting Wires Integrate electronics Provided With Arduino

Resistors Set up circuit for solar panels Provided With Arduino

Thermistor (5 one comes with Arduino)

Record Temperature 5 $1.95 Sparkfun

Micro SD Shield Can put micro SD card into Arduino for extra memory

53x52 10 $16.95 Sparkfun

16 Channel Multiplexer (1) Make additional readings with analog inputs on Arduino

8x9 $.95 Sparkfun

Multiplexer breakout board (1)

40x18 $4.95 Sparkfun

Foamcore Structure of satellite (see diagrams) 163 Provided Space Grant

Shipping $20Totals 793 $176.54

Mass/Budget

Message to Next Semester• This class will be one of the most rewarding and unique

experiences of your education. Gateway will give you an inside look into the life of an engineer through hands on experience. That being said, this class is very difficult and very time consuming. Be prepared to learn entire new concepts with little guidance in a very short amount of time. If you have the dedication then you will get through it, but it will be challenging. Start early, work hard, and you will have the time of your life.