Solar Powered Charging Station Final Presentation Design Team

Solar Powered Charging Station: Final Presentation Design Team: Ben Hemp Jahmai Turner Rob Wolf, PE Sponsors: Conn Center for Renewable Energy Dr. James Graham, Ph. D Dr. Chris Foreman, Ph. D Revision C, 12/10/11

Agenda • • • Project Overview System Requirements Detailed Design Trade Studies and Research Test Results 2

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 3

Project Overview The Test Subject • Manufactured by No. Gas 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 4

System Requirements 5

Harvest Energy from 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 k. W/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 6

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 7

Charging Station External Interfaces Charging Station • EV requires 120 VAC, 60 Hz, 1ɸ • NEMA 5 -15 R receptacle needed to charge EV 8

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 9

Detailed Design 10

Solar Panel Array 11

Solar Panels Alternative Energies 230 W • 230 W maximum DC per SP • Poly-crystalline cells • MC-4 connectors connect to inverters • 60 cells per SP, soldered in series • Vmax (1000 W/m 2, 25°C, AM 1. 5) = 29. 7 VDC • Imax (1000 W/m 2, 25°C, AM 1. 5) = 7. 5 A • ~18% efficient • Size = 39. 375” (~3. 25’) x 65. 5” (~5. 5’) • ~ 2. 0 yards 2 or 1. 9 m 2 12

Inverters 13

Inverters Enphase M 215 Distributed Inverter • Maximum input power: 260 W • Output power: 215 W • DC operation range: 16 V – 36 V • Maximum modules for 240 VAC 20 A 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 14

Inverters (continued) Enphase M 215 Distributed Inverter 15

Energy Meters 16

Energy Meters Eaton IQ 150 • Powered by 120 VAC • Capable of measuring: • Voltage (True RMS) – Up to 416 VAC • Amperage (True RMS) – 5 A nominal, 10 A maximum • k. W • k. VAR • Frequency • Communicates with Gateway via Modbus Protocol 17

Energy Meters (cont. ) Eaton IQ 150 18

Gateway Eaton PXG 600 A 19

24 VDC Power Supply Eaton EZ 400 -POW • Supplies 24 VDC to power the Gateway • Powered by 120 VAC 20

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 21

Trade Studies and Research 22

Test Results 23

Test Results Energy Meters Voltage (V) Line - Neutral Power (W), Reactive Power (VAR), Power Factor 24 Amperage (A)

Questions? 25