1. Adaptive Maze Finding a project through a changing maze of complications Project Team: Krista Miller Sohaib Hasan John Helme

2. Excess Thermal Energy From Solar Panels Problem: Solar panels installed in the Alternative Energy Laboratory can be damaged if heated to temperatures above 180° F.

3. Considered Solutions Energy Dumping System:  Dissipate excess heat by routing the solar panel output through underground coils. Energy Conversion System:  Dissipate excess heat by converting it to other forms of energy: Mechanical Energy – Stirling Engine Electrical Energy – Seebeck device Energy Blocking System:  Cover solar panels to reduce energy input.

4. Energy Dumping System Install valves and pipes to allow the output of the solar panels to run through underground pipes

5. Energy Dumping System Advantages  System is always on.  Few components.  Convection currents maybe used to allow the system to work without motors, sensors or switches. Disadvantages  Excess energy is lost  To simple to earn an acceptable grade.  Excavation and plumbing maybe to expensive.

6. Energy Conversion Systems How much excess energy is available? Q = cm(T 1 -T 2 )Q= Heat = energy c= specific heat c water = 4.186j/g°C For one kg of waterT1 = 90°F= 32.2°C Q=3669kJT2 = 180°F=90°C

7. Energy Conversion Systems How much power is being added to the system? Panel Characteristics Quantity10 Area2.96m 2 EfficiencyUp to 70% Solar insolation for Vermont = 400W/m 2 Power new = Quantity * Area * Efficiency * Solar insolation = 8288W

8. Energy Conversion– Stirling Engine The stirling engine uses a temperature differential cause gases to expand and compress. This expansion and compression is used to drive one or more cylinders.

9. Stirling Engine Advantages  High efficiency engine  Direct conversion from thermal energy to mechanical energy  Mechanical energy could be applied to cooling the facility Disadvantages  Very complicated and experimental  May require higher temperatures to work without using special gases  May not dissipate enough energy to keep the panels cool

10. Energy Conversion –Seebeck Device A voltage is created when there is a temperature difference between two different metals or semiconductors. V = (S B -S A ) * (T 2 -T 1 ) V = Voltage generated S = Thermoelectric Power Coefficient for materials A and B T = Temperature at junctions 1 and 2

11. Seebeck Device Seebeck Power Generation Module Output T 1 = 150°C, T 2 = 50°C5.8 W Price (each)$43.95 Approximate cost to generate 50W with a temperature difference of 50° $880.00

12. Seebeck Device Advantage  Thermal energy is converted to electrical energy  Electrical energy can be applied to other applications in the facility Disadvantage  Expensive  Will not dissipate enough energy to keep solar panels cool

13. Energy Blocking System Solar panels will be covered before the critical temperature of 180°F is reached. Covers will stop the panels from continuing to heat. Solar PanelPanel Screen

14. Energy Blocking System Advantages  Definitive control of solar panel heating process  Uses electro- mechanical devices and systems. Disadvantages  Potential energy is not acquired

15. Solution Summary SolutionResolves Problem Economically Feasible Conserves Energy Uses Electro- mechanical systems Dump heat into ground YesNo Sterling Engine No – limited heat dissipation UnknownYes Seebeck Device No – limited heat dissipation NoYes Energy Blocking Yes NoYes

16. Solution Statement Blinds or screens will be automatically positioned to cover a solar panel before the panel temperature reaches a critical level. Each panel will have an complete and independent blind system. The blind system for multiple panels can be controlled by a single override control.

17. Heat Blocking System Overview Water Temperature Sensor Motor to raise/lower panel Panel Assembly Controller Panel Position SensorsManual Override Battery Active Solar Panel

18. Above is a picture of how the solar panel cover will be mounted on the existing panels. Below is a photo of how the gears will rotate and move the shade up and down, to cover or uncover the panels. Mechanical System Diagrams

19. State Diagram

20. States of Panel Covers “Start”: Sun levels OK, not Overheating. “Cover Panel”: Too much Sun, Cover starts to slide over Panel due to Temperature exceeding limits. “Wait”: Panel finished being covered and is shielded from sun. “Remove Cover”: Temperature has been lowered, remove cover. “Wait”: Temperature has decreased, cover fully removed.

21. Solar Panel Covers Plastic Fabric: Advantages: Weatherproof Commercially Available Disadvantages: Wind will get ‘caught’ without holes to escape through Will have to have a fastening system Depending on material, can get hot Metal Shading: Advantages: Holes in it will allow wind to escape Commercially Available Attaches very well onto other things Disadvantages: Depending on metal, may rust Will get hot

22. Temperature Sensing Integrated Circuit  Advantages: Most Linear High Output High Accuracy Inexpensive  Disadvantages: Power Required Slow Self Heating Not meant to be used outdoors

23. Temperature Sensing Thermistor  Advantages: High Output Fast Two Wire Ohm Measurement  Disadvantages: Non Linear Limited Temperature Range Fragile Current Source Required Self Heating

24. Temperature Sensing RTD  Advantages: Stable Accurate  Disadvantages: Expensive Current Source Required Small ∆R Self Heating

25. Temperature Sensing Thermocouples  Advantages: Self Powered Simple Rugged Inexpensive Wide Temperature Range  Disadvantages: Non-Linear Low Voltage Sensitivity

26. Switches Lower Limit Switch Upper Limit Switch

27. Brushless DC Motors: Advantages: Increased Reliability & Efficiency Longer Life Elimination of Sparks from Commutator Reduced Friction Faster Rate of Voltage & Current Precision Voltage & Current Applied to Field Coils Disadvantages: Requires Complex Drive Circuitry Requires additional Sensors Higher Cost Some designs require manual labor (Hand wound Stator Coils)

28. Microcontroller Freescale HCS08  10bit analog to digital converter  Ease of use  Inexpensive  Available Code

29. Personnel Assignments

30. Expected Costs Cost EachQuantityCost Per Panel Motor$40.001 Panel Covering$50.001 Gears$2.504$10.00 Chain$1.5020$30.00 Gear Box$25.001 Cover Sensors$1.504$6.00 Temperature Sensors$1.252$2.50 Battery$50.001 Active Solar Panel$100.001 $313.50

31. Questions?