1 / 31

Introduction to Solar Power for ICT4D

Introduction to Solar Power for ICT4D. Stephen Okay Abdus Salam Int’l Center for Theoretical Physics Trieste, Italy February 27, 2008. “Solar Panels”. “Solar Panel” can mean multiple things Panel with tubing to heat hot water Panel containing photovoltaic cells to generate electricity

nathaniel-gates
Download Presentation

Introduction to Solar Power for ICT4D

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Introduction to Solar Power for ICT4D • Stephen Okay • Abdus Salam Int’l Center for Theoretical Physics • Trieste, Italy • February 27, 2008

  2. “Solar Panels” • “Solar Panel” can mean multiple things • Panel with tubing to heat hot water • Panel containing photovoltaic cells to generate electricity • This lecture covers this latter meaning

  3. PV Panel basics • Solar PV cells work via “photovoltaic effect” • photons hit the panel and “knock out” electrons in a silicon substrate, creating “gaps” in the electron shell of the silicon atoms which propagate through the substrate producing an electrical current • Only 10-15% efficient • Most photons pass through the silicon layer(s) • Some reflect off • Some are absorbed • ...and generate heat • remainder will generate electrical current via electron “gapping”

  4. Operational characteristics of PV panels • Power generated proportional to amount of light falling on them. • Share some characteristics with batteries • Weaker, damaged or shaded cells can drag down array performance forcing “good” cells to work harder under load. • Additional electronics needed to guarantee continuous rate of output. • Affected by heat and environment • Chemical structure affects efficiency and performance • Differences from batteries • Perform better in hot conditions, poorer in colder ones • P/N Junction forms diode limiting current flow back into panel

  5. Types of PV Cells • Silicon • Crystalline • Amorphous • Nanocrystalline • Non-Silicon photoreactive substances • Dye • Polymer • Thin Film

  6. Photovoltaic effect in a P-N junction PV panel Photons N - P-N Junction(Potential gap) - + Current P

  7. Measuring PV Cell Efficiency • Maximum Power Point • Point at which maximum power is generated for a given level of irrradiation. Calculated for positioning and alignment of PV arrays. • Basically an application of Ohm’s Law, seeking maximum V x I, minimal R • Energy Conversion Efficiency • Percentage of electrical power converted AND collected when a PV cell is hooked up to an open electrical circuit. • Quantum Efficiency • Percentage of photons received and converted into energy vs. photons received. • Not the same as Energy Conversion Efficiency, has more to do with wavelength of light being absorbed by panel • Link to Formulas for Calculating PV Efficiency

  8. Finding Maximum Power Point

  9. Series Construction of Solar PV Panels:Wiring Parallel 24V 350 mAh 6V 1400mAh Voltage additive, amperage constant Voltage constant, amperage additive series-parallel 6V 350mAh PV cell 24V 1400 mAh Both voltage and amperage are additive

  10. Construction cont’d: cells to panels

  11. Support Electronics • Power Inverter • Convert DC current from panels to AC • Leveling diodes • Balance power produced by panels to make up for defects/uneven performance in individual cells in a panel • Prevents battery from draining back into the panel(s) • Charge controller • Provides consistent level of current into the battery from current coming from the PV panels. • Sun-pointing system • Tracks sunlight and pans/tilts PV array towards max sunlight • Tends to be expensive. Analysis/study should be done to determine cost/benefit point. • Cheap solar tracker prototype

  12. Solar Arrays - Key Components PV(“Solar”) Panel array DC Inverter WiFi AP Bypass/Leveling diodes between panels deal with bad/shaded cells Charge Controller POE Injector Inveneo Comm Station 12V Deep Cycle Battery*

  13. Key Considerations for solar installations • Intended use • Primary power vs. Backup power • Panel Characteristics • Take 10% off the rated power immediately. Be prepared to lose another 5-10% after initial measurements. • Location • Insolation value(Geography/Climate Dependant) • Mounting/Positioning • Anti-theft/Anti-pest • Charge Controller • Battery • “Wet”/”Flooded” cell • Gel/Sealed cell

  14. Batteries • Variable quality and sizes around the world • “Wet” cells are by far the best in terms of charging, capacity, discharge curve, etc. but require maintenance and care • High temperatures yield greater output, but shorten useful life • Lower temperatures yield significantly lower performance but extend life • Like PV panels, requires electronics to compensate for “dumb” nature.

  15. Insolation / Climate affect feasibility of solar power • Insolation • Amount of solar energy received on a given area over time measured in kWh/m^2* • Decreases w/ cosine of angle from Normal(Equator=0, Poles=|90|) • Affected by • climate (cloud cover, seasonal weather, pollution, etc.) • local topography(mountains, tree cover, building density,etc) • seasons *From the Wikipedia entry

  16. Insolation / Climate • Climate has additional effects beyond contribution/influence on insolation calculations • Batteries • Better performance in hot climates, but store poorly • Significant performance hits(-20% or >) in cold climates, but store well • PV Panels • Opposite of batteries

  17. Costs • May 2007 • PV Panel $4.50/Watt • Charge Controller $35(10A model) • 100Ahr AGC Battery $130-150 • Mounting hardware: UniRac < $50-80/panel, Custom frame/mountings and installation at local market rates.

  18. Insolation Maps: Americas

  19. Insolation Maps:Africa/Near East/Asia/Oceania

  20. Insolation Maps: Europe

  21. Use of solar power at Inveneo installations • Solar Power Equipment(per computing station) • 110W PV panel delivering 12V DC • Phocos CML-10 Charge Controller • Universal UB121000 sealed AGM battery(100A hr) • 25A fuse/circuit breaker between battery and controller • Heavy Gauge(#8 or lower) wiring • Mounting hardware & tools for roof/structure mounting • Powering... • Inveneo Comm. Station: Computer, Wireless AP and VOIP ATA • 20W draw when all components on, 4W for just WiFi and ATA • Computer, AP, ATA can be individually on/off • AP & VOIP can run 24/7, computer 5-6 hours/day* *Assuming at least 6 hours direct sun per day with a margin for 1 “rain day”. This can be pushed to 2-3 days w/ additional usage monitoring/management.

  22. Use of solar power at Inveneo installations • Insolation and climate • Uganda - Solar is backup power • semi-stable power via mains or generator • Rainy season affects long-term utility/reliability • Burkina-Faso - Solar is primary power source • No mains power in most regions • Dry, arid climate, nearly constant sunlight(high insolation value)

  23. Inveneo in Burkina Faso

  24. Inveneo in Burkina-Faso: Solar arrays at Komtoego

  25. Komtoega School, Burkina Faso

  26. ActionAid Village Empowerment Program - the ICT Reflect Circle • Rural Uganda

  27. Solar power size & capacity planning links • National Renewable Energy Lab(NREL) HOMER Evaluation software • http://www.nrel.gov/homer • Advanced Energy Group(AEG) Solar Installation Calculator • http://www.solar4power.com/solar-power-sizing.html#solar • How to wire Solar PV Panels • http://www.partsonsale.com/learnwiring.htm • Guide to Solar Charge Controllers: • http://www.solar-electric.com/charge_controls/solar_charge_controllers.htm • Battery usage FAQ • http://www.windsun.com/Batteries/Battery_FAQ.htm • Calculating MPPT, Energy efficiency, etc. • http://en.wikipedia.org/wiki/Photovoltaic_effect#Silicon_processing

More Related