8/21/2017

1

Solar Mini‐BlindsWith DC‐DC converters and a supercapacitor storage medium

By Josh Stetzel

Date: April 24, 2017

Project Advisor: Dr. Hadi Alasti

Course Instructor: Prof. Paul I‐Hai Lin

CPET 491 Senior Design Phase II

1

Topics of Discussion

• Problem topic

• Feasibility

• Solar Energy Collection and Conversion

• Electrical Energy Storage

• Fabrication

• Requirements

• Circuit Design

• Simulation

• Prototype

• Testing

• Demos

2

8/21/2017

2

Executive Summary

• Reduce the dependency on fossil fuels

• Utilize photovoltaic energy and convert to electrical energy

• Store electrical energy with supercapacitors

• Deliverable include the prototype, final report, and project presentation

• Cost was around $200

• Took about 130 hours to complete

3

Problem Topic

• Natural resources are limited

• Renewable energy is the future (if we want a future)

• Currently 67% of electrical energy is produce with fossil fuels

4

8/21/2017

3

Feasibility

• Solar mini‐blinds will perform best in winter months

• Set it and forget it

• Li‐ion batteries more suitable

• Supercapacitor are impractical, but used to gain knowledge

5

Solar Energy Collection and Conversion

• 6 solar cells per solar panel

• 8 solar panels attached to mini‐blinds

• Output has been as high as 25V at 210mA

• Output voltage is regulated to 5V±0.5V

6

8/21/2017

4

Electrical Energy Storage

• 400F * 6 at 2.7 volt supercapacitors are in series

• Input voltage is boosted to 17 volts

• Output voltage is bucked down to 5V

• Utilized 4 diodes as leveling circuit

7

Fabrication Process

• Create solar panels from solar cells

• Mount solar panels

• Prototype circuitry

• Build supercapacitor pack

• Mount and connect circuitry

8

8/21/2017

5

Solar Cells

• Silicon Polycrystalline cells were chosen

• Cheaper than monocrystalline

• Produce less power and waste to manufacture

• About 17% efficiency

• 0.6% efficiency decay per year

• 0.6V open circuit voltage per cell

• 200mA short circuit current per cell

9

Storage Element‐Supercapacitors

• Expensive, relatively high capacity compared to normal capacitors

• Low no‐load leakage current, 0.85mA after 72 hours

• Can be stored for several days with usable energy

• Requires leveling circuit for series configuration

10

8/21/2017

6

Supercapacitor Wiring diagram

11

C1400FSupercapacitor

D1

1N5400D2

1N5400D3

1N5400D4

1N5400

C2400FSupercapacitor

D5

1N5400D6

1N5400D7

1N5400D8

1N5400

C3400FSupercapacitor

D9

1N5400D10

1N5400D11

1N5400D12

1N5400

C4400FSupercapacitor

D13

1N5400D14

1N5400D15

1N5400D16

1N5400

C5400FSupercapacitor

D17

1N5400D18

1N5400D19

1N5400D20

1N5400

C6400FSupercapacitor

D21

1N5400D22

1N5400D23

1N5400D24

1N5400NEG

Pos

Requirements

• Physical Requirements

• Functional Requirements

• Operational Requirements

• Environmental Requirements

• Performance Requirements

12

8/21/2017

7

Circuit Design

• LM2678T simple switcher for buck converter• 8‐30 volts in, 5 volts out, max 5A

• LM2585 simple switcher for boost converter• 4‐40 volts in, max 65 volts out, 3A max output

• Utilized standard USB connectors for inputs and outputs

13

Boost Converter Circuit

14

V15V

Rb1

2.94kΩ

Rb2

1.5kΩRb3

19.1kΩ

Cb1150µF Cb2

330µFCb3470nF

Lb1

68µH

Db1

1N4447

Ub1

lm2585

123 4

5

Pos

Neg

To Supercapacitors

From SolarPanels

8/21/2017

8

Buck Converter Circuit

15

V125V

Cp10.47µFCp2

15µF

Cp310nF

Lp1

22µHCp4180µF

Cp5180µF

Dp110TQ045

Up1

LM2678t

1234 5

67

Jp1

USB Type A

VBUS1

D+3

D-2

GND4

ShellCASE1,CASE2

Cp615µFCp7

15µF

From SolarPanels

To ChargeMedium

Supercapacitor Pack

16

8/21/2017

9

Supercapacitor Pack Simulation

17

Prototype

• Completed on breadboard first

• Checked for proper voltage

• Transferred over to protoboard

18

8/21/2017

10

Protoboard Buck converter

19

Protoboard Buck/Boost Converter

20

8/21/2017

11

Testing

• Various tests were performed through a Rheostat

• Tests were performed outside on the 23 of April, sunny and 68°F

• Solar panels without regulation circuitryVoltage Current Load resistance

from Rheostat

10V 300mA 35Ω

12V 280mA 41Ω

24V 200mA 165Ω

25V 170mA 193Ω

26V 130mA 260Ω

26V 100mA 355Ω

21

Vsc1

0.5V

Vsc2

0.5V

Vsc3

0.5V

Vsc4

0.5V

Vsc5

0.5V

Vsc6

0.5V

Vsc7

0.5V

Vsc8

0.5V

Vsc9

0.5V

Vsc10

0.5V

Vsc11

0.5V

Vsc12

0.5V

Vsc13

0.5V

Vsc14

0.5V

Vsc15

0.5V

Vsc16

0.5V

Vsc17

0.5V

Vsc18

0.5V

Vsc19

0.5V

Vsc20

0.5V

Vsc21

0.5V

Vsc22

0.5V

Vsc23

0.5V

Vsc24

0.5V

Vsc25

0.5V

Vsc26

0.5V

Vsc27

0.5V

Vsc28

0.5V

Vsc29

0.5V

Vsc30

0.5V

Vsc31

0.5V

Vsc32

0.5V

Vsc33

0.5V

Vsc34

0.5V

Vsc35

0.5V

Vsc36

0.5V

Vsc37

0.5V

Vsc38

0.5V

Vsc39

0.5V

Vsc40

0.5V

Vsc41

0.5V

Vsc42

0.5V

Vsc43

0.5V

Vsc44

0.5V

Vsc45

0.5V

Vsc46

0.5V

Vsc47

0.5V

Vsc48

0.5V

Pos

Neg

Testing

• Buck converter testing with a current limited power supply

Voltage

input

Current

input

Voltage

output

Current

output

Load

resistance

25.4V 110mA 4.6V 240mA 19.7Ω

25.7V 100mA 4.7V 180mA 26.0Ω

25.4V 60mA 4.8V 150mA 32.0Ω

25.2V 40mA 4.8V 110mA 60.6Ω

25.0V 30mA 4.8V 80mA 60.6Ω

25.0V 30mA 4.9V 60mA 80.6Ω

25.3V 20mA 4.9V 40mA 123.8Ω

25.5V 10mA 4.9V 20mA 247.0Ω22

8/21/2017

12

Testing

• Buck converter testing with solar panels

Voltage Current Load resistance

from Rheostat

4.77V 150mA 30.7Ω

4.81V 110mA 41.9Ω

4.84V 90mA 54.9Ω

4.87V 60mA 80.0Ω

4.89V 40mA 125Ω

4.91V 20mA 242Ω23

Final Integration Testing

24

8/21/2017

13

Physical RequirementsRequirement Data Verification Planning

IDRequirement

Type

Requirement (Shall or Should

statements)

Verification

MethodDate Verified

Verification

Report

6 PhysicalThe system shall integrate solar

cells onto window blindsInspection 4‐24‐17

7 PhysicalThe system shall have at least

one USB interfaceInspection 4‐24‐17

8 PhysicalThe system shall incorporate a

voltage regulation circuitInspection 4‐24‐17

9 Physical

The system shall store electrical

energy in rechargeable

batteries

Inspection 4‐24‐17

25

Functional RequirementsRequirement Data Verification Planning

IDRequirement

Type

Requirement (Shall or Should

statements)

Verification

MethodDate Verified

Verification

Report

10 FunctionalThe system shall capture solar energy with photovoltaic cells

Inspection 4-24-17

11 FunctionalThe system shall incorporate a buck/boost converter

Inspection 4-24-17

26

8/21/2017

14

Operational RequirementsRequirement Data Verification Planning

IDRequirement

Type

Requirement (Shall or Should

statements)

Verification

Method

Date

Verified

Verification

Report

1 OperationalThe system shall capture solar energy

Inspection 4-24-17

2 OperationalThe system shall convert solar energy into electrical energy

Inspection 4-24-17

3 OperationalThe system shall store the captured solar energy as electrical energy

Test 4-24-17

4 OperationalThe system shall provide a D.C. output to power a user's device

Test 4-24-17

5 OperationalThe system should supply D.C. power via the USB interface

Demonstration 4-24-1727

Environmental RequirementsRequirement Data Verification Planning

IDRequirement

Type

Requirement (Shall or Should

statements)

Verification

MethodDate Verified

Verification

Report

18Environmen

talThe system shall be exposed to direct sunlight

Inspection 4-24-17

19Environmen

tal

The system shall operate between 60 and 80 degrees F

Test 4-24-17

28

8/21/2017

15

Performance Requirements

Requirement Data Verification Planning

IDRequirement

Type

Requirement (Shall or Should

statements)

Verification

Method

Date

Verified

Verificatio

n Report

12 Performance The D.C. output shall be 5V ± .5V Demonstration 4/24/17 4.89V

13 PerformanceThe D.C. output shall be capable of supplying the battery with at least 200 milliamps of current

Test4-24-17

300mA

max

14 PerformanceThe fully charged system shall be able to deliver >= 4W

Test4-24-17

29

Performance Requirements

Requirement Data Verification Planning

IDRequirement

Type

Requirement (Shall or Should

statements)

Verification

Method

Date

Verified

Verificatio

n Report

15 PerformanceThe voltage regulator shall not exceed 100 degrees F

Test4-24-17

16 PerformanceThe current shall be limited to 1.0 amps

Test4-24-17

300mA

max

17 PerformanceThe batteries should be capable of at least 1000 mAh of energy

Test4-24-17

30

8/21/2017

16

CostMaterial/Tool Cost

Item Qty Cost Each Total Cost Comments

PCB board 3 $ 0.50 $ 1.50

LM2678T 2 $ 5.82 $ 11.64

LM2585 1 $ 6.42 $ 6.42

Resistors 4 $ 0.10 $ 0.40

Capacitors 17 $ 1.00 $ 17.00

Diode 28 $ 0.54 $ 15.12

Inductor 3 $ 2.00 $ 6.00

Mini‐blinds 1 $ 50.00 $ 50.00

Supercapacitor 6 $ 12.00 $ 72.00

Solar cell 50 $ 0.28 $ 14.00

$ ‐

Material Total $ 194.08 31

Project Management

32

8/21/2017

17

Project Management

33

Original Risk Register

34

ID Entry Date Type

Risk Description: 'IF statement'

Consequence of Risk:

'THEN statement' Status

Likelihood (1-5)

Severity (1-5) Score Rank* Response

Description of Response

1 2-Nov-16 Schedule IF The solar cells will take too long to acquire

THEN The integration will be delayed

Open 2 3 6 Low Mitigate order them

asap

2 2-Nov-16 Technical IF The current from the solar cells is too great

THEN Output current would be outside of parameters

Open 3 2 6 Low Mitigate Add a current

regulating circuit

3 2-Nov-16 Technical IF If the solar cells are too heavy THEN

the mini blinds won't hold the cells, and won't be able to capture sunlight

Open 1 4 4 Low Accept

4 2-Nov-16 Technical IF It the overcharge circuit malfunctions THEN

The battery could explode Open 2 5 10 Medium Mitigate

Use a watchdog function to

keep tabs on charging

5 2-Nov-16 Cost IF If my components use too much power THEN

Must replace with better component Open 1 2 2 Low Accept

6 2-Nov-16 Cost IF The battery gets damaged THEN

Battery must be replaced Open 3 3 9 Medium Mitigate

have a spare battery on

hand

7 2-Nov-16 Schedule IF if the overcharge system won't work

THEN it will need to be redesigned, leading to a schedule delay

Open 2 4 8 Medium Mitigate

Model the system before

ordering parts

8/21/2017

18

Risk Register Rev. 4

35

Risk Matrix

36

8/21/2017

19

Conclusion

• Solar panels would work better on a mobile platform

• Li‐ion batteries would be more suitable

• Learned valuable information about supercapacitors

• Gained knowledge on solar energy

37

References

38

Buchmann, I. (2017, Feburary 19). Bu‐209: How does a Supercapacitor Work. Retrieved from Battery University: http://batteryuniversity.com/learn/article/whats_the_role_of_the_supercapacitor

Energy, U. D. (2017, Feburary 19). Frequently Asked Question. Retrieved from U.S. Energy Information Administration: https://www.eia.gov/tools/faqs/faq.cfm?id=427&t=3

M. Ameer Ur Rehman Sheikh, M. S. (2014). Voltage Balancing of Supercapacitors String using Rectifier Diodes: Analytical and Simulation Ap‐proach. International Journal of Scientific & Engineering Research, 1290‐1295.

Maehium, M. A. (2017, Feburary 19). The Real Lifespan of Solar Panels. Retrieved from energy informative: http://energyinformative.org/lifespan‐solar‐panels/

8/21/2017

20

Questions/Comments?

39

Demo With Li‐ion Battery

40

8/21/2017

21

Demo With Supercapacitor Pack

41