solar powered charging station: final presentation

Solar Powered Charging Station:Final PresentationDesign Team:Ben HempJahmai TurnerRob Wolf, PE

Sponsors:Conn Center for Renewable EnergyDr. James Graham, PhDDr. Chris Foreman, PhD Revision C, 12/10/11

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

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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

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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

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System Requirements

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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

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Convert Energy into a Usable FormInverter• 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

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Charging Station External Interfaces

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

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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

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Detailed Design

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Solar Panel Array

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Solar PanelsAlternative 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 yards2 or 1.9 m2

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Inverters

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InvertersEnphase 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

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Inverters (continued)

Enphase M215 Distributed Inverter

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Energy Meters

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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 17

Energy Meters (cont.)

Eaton IQ150

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Series Connection Through Current

Transformer From Solar Panel Branch

Series Connection Through Current

Transformer From Building Branch

Building’s Ground

Building’s Line

Building’s Neutral

Gateway

Eaton PXG600A

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24 VDC Power SupplyEaton EZ400-POW• Supplies 24 VDC to power the Gateway• Powered by 120 VAC

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Current TransformersEaton • 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

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Trade Studies and Research

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Test Results

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Test ResultsEnergy Meters

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Voltage (V) Line - Neutral Power (W), Reactive Power (VAR), Power Factor

Amperage (A)

Questions?

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