SunPower T0 Washing System by Charlie Joy Atlund Smith David Hohn Eric Wallace Mechanical Engineering Department California Polytechnic State University San Luis Obispo 2010 Statement of Confidentiality The complete senior project report was submitted to the project advisor and sponsor. The results of this project are of a confidential nature and will not be published at this time. Statement of Disclaimer Since this project is a result of a class assignment, it has been graded and accepted as fulfillment of the course requirements. Acceptance does not imply technical accuracy or reliability. Any use of information in this report is done at the risk of the user. These risks may include catastrophic failure of the device or infringement of patent or copyright laws. California Polytechnic State University at San Luis Obispo and its staff cannot be held liable for any use or misuse of the project. SunPower T0 Washing System Eric Wallace [email protected] Atlund Smith [email protected] David Hohn [email protected] Charlie Joy [email protected] Contents Introduction .............................................................................................................................................. 1 Background ............................................................................................................................................... 1 Cleaning Methods ................................................................................................................................. 1 Soiling Methods .................................................................................................................................... 3 Measuring Cleanliness .......................................................................................................................... 4 Objectives ................................................................................................................................................. 4 Design Requirements ............................................................................................................................ 4 Engineering Specifications .................................................................................................................... 5 Method of Approach ................................................................................................................................ 6 Design Development ................................................................................................................................ 7 Ride‐on‐Panel Concept ......................................................................................................................... 7 Drive Up Row Concept .......................................................................................................................... 8 Linear Move Concept ............................................................................................................................ 9 Aisle Concept ........................................................................................................................................ 9 Decision Process ................................................................................................................................. 10 Revised Project .................................................................................................................................... 10 Decision Process for Test Rig .............................................................................................................. 10 Description of Final Design ..................................................................................................................... 12 Design Description .............................................................................................................................. 12 Analysis ............................................................................................................................................... 14 Safety Considerations ......................................................................................................................... 14 Maintenance ....................................................................................................................................... 15 Build Plan ................................................................................................................................................ 15 Verification Plan ..................................................................................................................................... 17 Testing .................................................................................................................................................... 17 Experimental Procedure ..................................................................................................................... 17 Equipment List .................................................................................................................................... 18 Data Analysis ....................................................................................................................................... 19 Future Considerations ............................................................................................................................ 20 Water tank .......................................................................................................................................... 20 Water Treatment ................................................................................................................................ 20 Repeatability ....................................................................................................................................... 21 Soiling method .................................................................................................................................... 22 Data collection .................................................................................................................................... 22 Reference Cell Use .............................................................................................................................. 22 Two phase ........................................................................................................................................... 23 Safety .................................................................................................................................................. 23 Alternative Cleaning Methods ............................................................................................................ 24 Conclusions and Recommendations ....................................................................................................... 28 Nozzle Type ......................................................................................................................................... 28 Nozzle Fan Angle ................................................................................................................................. 28 Stand‐Off ............................................................................................................................................. 28 Operating Pressure ............................................................................................................................. 29 Panel Orientation ................................................................................................................................ 29 Boom Orientation ............................................................................................................................... 29 Hard Water Mitigation ........................................................................................................................ 29 References .............................................................................................................................................. 30 Appendix A: Decision Matrix .................................................................................................................. 33 Appendix B: Supporting Analysis ............................................................................................................ 34 Appendix C: Bill of Materials .................................................................................................................. 37 Appendix D: Build and Test Plan – Phase I ............................................................................................. 39 Appendix E: Main Test Data ................................................................................................................... 42 Appendix E : Reference Cell and Pyranometer Consistency Testing Results ......................................... 47 Appendix F. Picture Contents by Picture Number .................................................................................. 50 Appendix G: Nozzle Data from Spraying Systems Co. Technical Reference ........................................... 54 Appendix H: Pictures of Equipment Used .............................................................................................. 55 Introduction The initial purpose of this project was to develop a system to clean T0 ground mounted trackers installed in large solar power plants in order to improve overall electrical output. To justify cleaning, the system’s