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Solar Powered Charging Station: Final Presentation. Design Team: Ben Hemp Jahmai Turner Rob Wolf, PE. Sponsors: Conn Center for Renewable Energy Dr. James Graham, PhD Dr. Chris Foreman, PhD. Revision C, 12/10/11. Agenda. Project Overview System Requirements Detailed Design
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Solar Powered Charging Station:Final Presentation Design Team: Ben Hemp Jahmai Turner Rob Wolf, PE Sponsors: Conn Center for Renewable Energy Dr. James Graham, PhD Dr. Chris Foreman, PhD Revision C, 12/10/11
Agenda • Project Overview • System Requirements • Detailed Design • Trade Studies and Research • Test Results
Project Overview System Goals • Charge an electric vehicle (EV) from a charging station using 110 VAC, 60 Hz, 1ø as the charging source • Use power created by solar panels (SP’s) for the EV charging • Use grid-tied energy to make the charging times more predictable • Use instrumentation to monitor the energy created by charging station and energy used by electrical grid • This semester’s team is expected to design the complete system, but is only expected to implement the solar charging aspect due to planning with subcontractors
Project Overview The Test Subject • Manufactured by NoGas LLC in Nashville, TN • 50 MPH top speed/50 mile range • 72 VDC, 40 AH Lithium batteries with Battery Management System (BMS) • Regenerative braking • Built-in charger • 120 VAC charging with 1 to 8 hr. max charge time
Harvest Energy from Solar Panels Solar Panels • A solar array of multiple SP’s for solar charging • A solar study should be conducted to determine the number and size of SP’s needed to charge the scooter • Solar study determined seven solar panels are needed to reach 3.5 kW/day for worst case month • Conn Center funded two panels by vendor of choice • Decisions regarding fabrication technology and make/buy • Funded by Conn Center • Mounting location and attachment techniques must be determined (W.S. building, build structure, etc.) • “Cart-style” structure chosen for mobility
Convert Energy into a Usable Form Inverter • Inverters are needed to convert DC power from SP’s to AC power for charging station • Must operate with two 230 W SP’s • Must tie to grid • Limited to two breakers in W.S. breaker panel • Expandability Transformer • Required to charge EV with 120 VAC • Converts 240 VAC from inverters to 120 VAC for EV
Charging Station External Interfaces Charging Station • EV requires 120 VAC, 60 Hz, 1ɸ • NEMA 5-15R receptacle needed to charge EV
Monitoring, Control, and Data Logging Energy Meters • Monitor real-time power information from two of three branches • Power flow from solar array • Power flow from building Gateway • Record power information from energy meters • Stores data in a file • Retrievable from web-interface • Can be read from word processors or spreadsheet programs
Solar Panels Alternative Energies 230W • 230W maximum DC per SP • Poly-crystalline cells • MC-4 connectors connect to inverters • 60 cells per SP, soldered in series • Vmax (1000W/m2, 25°C, AM 1.5) = 29.7 VDC • Imax (1000W/m2, 25°C, AM 1.5) = 7.5A • ~18% efficient • Size = 39.375” (~3.25’) x 65.5” (~5.5’) • ~ 2.0 yards2or 1.9 m2
Inverters Enphase M215 Distributed Inverter • Maximum input power: 260W • Output power: 215W • DC operation range: 16V – 36V • Maximum modules for 240VAC 20A branch circuit: 17 • Inverters operate independently • Low-voltage operation • 96% efficiency • Works with 60-cell SP’s • Plug-and-play trunk cabling • No high voltage DC wiring • Complies with IEEE 1547 Anti-Islanding code
Inverters (continued) Enphase M215 Distributed Inverter
Energy Meters Eaton IQ150 • Powered by 120 VAC • Capable of measuring: • Voltage (True RMS) – Up to 416 VAC • Amperage (True RMS) – 5A nominal, 10A maximum • kW • kVAR • Frequency • Communicates with Gateway via Modbus Protocol
Energy Meters (cont.) Eaton IQ150
Gateway Eaton PXG600A
24 VDC Power Supply Eaton EZ400-POW • Supplies 24 VDC to power the Gateway • Powered by 120 VAC
Current Transformers Eaton • Measure current at specific branches in the circuit • 120 VAC wire from building to node • 120 VAC wire from transformer to node • Ratio used to compare current through the CT (branch circuit) vs. current output to the energy meters • Each CT is rated for a 50/5 ratio • Wire is wrapped twice for a 25/5 ratio • Better accuracy
Test Results Energy Meters Voltage (V) Line - Neutral Power (W), Reactive Power (VAR), Power Factor Amperage (A)