Solar Powered, Multi-seated, Internetted Computer System Final Report December 3rd, 2008
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- Section 1 - Photovoltaic System Design
- Determining Size of Photovoltaic Panel Array
- Determining Solar Insolation Levels
Table of ContentsExecutive Summary 3 Acknowledgement 5 Table of Contents 7 Section 1 - Photovoltaic System Design 9 Determining Size of Photovoltaic Panel Array: 9 Determining Load Power Consumption: 9 Determining Solar Insolation Levels: 11 Sizing Battery Array 13 Wire Sizing and Connections: 15 Maximum Solar Power Output: 15 Inverter to Battery Wiring 17 DC-AC Inverter 18 Charge Controller 19 Conclusion 21 Section 2 - Power Management 22 Research 22 Voltage Measurements 23 Control Board 25 Power Management Board 26 Conclusion 26 Section 3 - Multi Seat System Hardware and Software 28 Thin Clients 32 Multiple-Motherboards 33 Multi-User 34 Testing/Conclusion 35 Section 4 - System Integration and Conclusion 36 Integration 36 Safety 37 Future Improvements: 38 Intelligent Monitoring 39 Conclusion: 42 Appendix 1 – Technical Roles and Responsibilities 44 Eric Tarkleson 44 Joshua Wong 46 Jakub Mazur 48 Ben Kershner 49 Appendix II - Schematics 50 Appendix III – Gantt Chart 52 52
Appendix IV - Nomenclature 53 Appendix V - References and Recommended Reading 54 Section 1 - Photovoltaic System Design
There are many types of solar systems but most can be categorized into a variation of the following: A “grid-tie” system where there are no batteries and the power grid provides back-up power. A hybrid “grid-tie” system where the power grid provides back-up for the solar panels and batteries act as a backup for the grid. In cases where there is no access to grid power an “off-grid” system is used, in which the battery bank stores and provides all the energy for the system without a backup. Since this is generally the case in under-developed areas this will be the system discussed here. There are also systems with generators as backups, they are comparable to “grid-tie” systems and will also be omitted from discussion here. Determining Size of Photovoltaic Panel Array:There are several steps involved in sizing the PV array, determining load power consumption, accounting for losses and dividing by solar insolation levels for deployment region. Determining Load Power Consumption:The first step is to determine how much power the total system load will draw. Power is measured in Watts: P = V ∗ I (Joule’s Law) However, the power rating is more useful when looked at in terms of time, this is indeed how electric companies charge consumers. For example a 200Watt light bulb running for 24 hours uses 4.8 KWh. 200Watts ∗ 24hrs = 4800 Watt-Hours or 4.8 KWh A list of all devices connected to the system should be made with their appropriate power draw available from specifications sheets or better yet, actual measurements.
Figure 2 - Power measurements on 11/11/2008. Note: Headsets, Keyboards & Mice are currently not included in calculations because the team is not in possession of them and their power consumption should be minimal. Since these devices are designed to plug into AC power, a DC-AC power inverter is needed. The power inverter ideally operates at 90% efficiency. Therefore the maximum inverter draw from batteries is: 238 Watts / 0.90 = 264.60 Watts This system power draw is then multiplied by the amount of hours per day that it will operate. 264.60 Watts ∗ 8hrs/day = 2116.80 Watt Hrs/day To compensate for system losses during battery charge/discharge cycles the total system power consumption is multiplied by a 20% compensation factor (Sunwize). 2115.52 Watt Hrs/day ∗ 1.2 = 2540.16 Watt Hrs/day Determining Solar Insolation Levels:In order to determine a good approximation of how much power the PV panels will output, solar insolation levels need to be considered. Solar insolation is the amount of incoming solar radiation incident on a surface, for PV applications the surface of interest is the earth’s surface. The values of solar insolation are commonly expressed in kWh/m2/day, which is the amount of solar energy that strikes a square meter of the earth's surface in a single day. This is commonly referred to as a “Sun-Hour-Day”. The amount of insolation received at the surface of the Earth is controlled by the angle of the sun, the state of the atmosphere, altitude, and geographic location. 
Figure 3 - World insulation levels. This map divides the world into six solar performance regions based on winter peak sun hours. It is important to keep this in mind when designing the system because as seen below in Figure 4, during the winter you have a much smaller ‘Solar Window’. Worst case scenarios should be calculated as it is better to have extra energy in the summer than not enough in the winter. Therefore the “Sun-Hour-Day” values for December (since December days are shortest) are generally used. 
Figure 4 - Sun path chart.  Figure 5 - Hankins. Solar Insolation Levels for Arusha, the prototype deployment area, are seen below in Figure 5. The compensated total power consumption per day value calculated above is then divided by the solar insolation values for given deployment region to determine minimum PV panel array power output requirement: 2540.16 Watt Hrs/day / 5.5 = 461.84 Watts Directory: classes -> ece480 -> capstone classes -> Unit 1: Exploration and Colonization classes -> Ap united States History Course Description classes -> Industrial Revolution classes -> 1–xx. The Redevelopment of a Warm Core Structure in Erin: a case of Inland Tropical Storm Formation classes -> Unit 7 Notes Organizer: C. Increasing Influences and Challenges); D. Challenges at Home & Abroad The United States in a Changing World (wwi) classes -> Unit 1: Colonial America (Twelve Days) Standard 1-2 Unit 2: Revolution (Ten Days) classes -> Review of Chapters 1-3, 8, and the appendix classes -> Seasonal Influences upon and Long-Term Trends in the Length of the Atlantic Hurricane Season capstone -> Configuring a Computer and Android Device for Android Development and Hardware Testing capstone -> Sponsor: Texas Instruments Ram Sathappan Download 4.42 Mb. Share with your friends:
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