Executive SummaryAcknowledgementSection 1 - Photovoltaic System DesignDetermining Size of Photovoltaic Panel Array:Determining Load Power Consumption:Determining Solar Insolation Levels:Sizing Battery ArrayWire Sizing and Connections:Maximum Solar Power Output:Inverter to Battery WiringDC-AC InverterCharge ControllerConclusionSection 2 - Power ManagementResearchVoltage MeasurementsControl BoardPower Management BoardConclusionSection 3 - Multi Seat System Hardware and SoftwareThin ClientsMultiple-MotherboardsMulti-UserTesting/ConclusionSection 4 - System Integration and ConclusionIntegrationSafetyFuture Improvements:Intelligent MonitoringConclusion:Appendix 1 – Technical Roles and ResponsibilitiesEric TarklesonJoshua WongJakub MazurBen KershnerAppendix II - SchematicsAppendix III – Gantt ChartAppendix IV - NomenclatureAppendix V - References and Recommended ReadingSolar Powered, Multi-seated,Internetted Computer SystemFinal ReportDecember 3rd, 2008Sponsored By:In Cooperation With:Michigan State University University of Dar es SalaamECE 480 - Design Team #2 - Fall 2008Management Jakub MazurWeb Josh WongDocument Ben KershnerPresentation/Lab Eric TarklesonExecutive SummaryWith the increasing proliferation of affordable, reliable personal computers into the marketplace, there is a great demand to develop affordable personal computers for remote and underdeveloped areas. Before deploying a computer system into such harsh conditions several obstacles must be overcome, including source of electricity, telecommunications, and the savannah climate. The Lenovo Corporation has tasked this team to develop a solar-powered computer workstation that can accommodate up to eight users. The solution must be robust enough to withstand the harsh environment with as little technical maintenance as possible, yet still be affordable for rural schools.A bank of solar panels charges a small battery bank using a commercially available charge controller. A custom engineered battery management system monitors voltages and currents from the solar panels and the battery to calculate system data. The system also monitors case temperatures to insure everything is operating within a safe range. Should the battery become discharged or temperatures rise above the safe limits the system will automatically shut itself down. All power data is logged to the computer and stored for system optimization. A small LCD panel displays pertinent system informationA single computer can connect up to 8 monitors, keyboards and mice. Each terminal allows independent simultaneous logons. The operating system is Linux based and uses only free and open source software (hereinafter referred to as FOSS).Since this project has three vastly different, but equally important main tasks that needed to be researched, tested, and built this report is split into three main sections. First is solar power system design, second is power management, and thirdis Multi seat hardware and software. Each section will address the research, design issues, testing, and conclusions that were found. The last section will deal with system integration and project findings and conclusions. Since we did not deal with the telecommunications issues these will not be addressed in this report.2AcknowledgementWe would like to thank our sponsor, Lenovo, for their help in making this project a success. We also would like to thank our team members in the Telecommunications department as well as the faculty and students working with usat the University of Dar Es Salaam, Tanzania.Also we would like to thank LEM and Man vs. Machine for their donations and samples. Their engineers and salespeople were very helpful in guiding us in the right direction.This project would not have been possible without the help of our facilitator Dr. Jian Ren. Also we would like to thank Dr. Goodman for helping keep us on track and helping us plan our deployment of this project in Tanzania.3Figure 1 - Power system block diagram.4Table of ContentsSolar Powered, Multi-seated, Internetted Computer System 1Executive Summary................................................................................................................................................ 2Acknowledgement................................................................................................................................................... 3Section 1 - Photovoltaic System Design.......................................................................................................... 7Determining Size of Photovoltaic Panel Array:............................................................................................7Determining Load Power Consumption:......................................................................................................... 7Determining Solar Insolation Levels:................................................................................................................ 8Sizing Battery Array.............................................................................................................................................. 11Wire Sizing and Connections:............................................................................................................................ 12Maximum Solar Power Output:........................................................................................................................ 13Inverter to Battery Wiring.................................................................................................................................. 14DC-AC Inverter.......................................................................................................................................................... 15Charge Controller................................................................................................................................................... 16Conclusion.................................................................................................................................................................. 17Section 2 - Power Management....................................................................................................................... 18Research...................................................................................................................................................................... 18Voltage
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