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Group 10
Amber Scheurer, EE
Eric Ago, EE
Sebastian Hidalgo, EE
Steven Kobosko, EE
System Overview
Solar
Array
MPPT Charge
Controller
LCD
Inverter
Battery
Wireless
Wireless
We designed a charge controller that implements
MPPT and demonstrates it in a fully functional standalone photovoltaic system.
Motivation and
Value of Project
Maximize the cost return on investment
for solar panels by using Maximum Power
Point Tracking (MPPT) algorithms
LCD screen and wireless data transfer
Useful for testing, research, and
maintenance
Potential for industrial scaling
Incorporate a charge controller system
with one controller per panel
Goals
Charge controller has to be inherently low power
Utilize Maximum Power Point Tracking to
increase efficiency
User/Researcher Friendly Design
LCD Screen
Wireless Data Transfer to Computer Station
Inexpensive
Specifications
Solar Panel delivers > 14 V
Total System Power Output > 200 W
12 V Battery with > 30 Ah
Wireless range > 20 m
Approximately 90% Efficient
PV Panel
Light
Sensor
Temp.
Sensor
Charge Controller
LCD Screen
Current
Sensor
Voltage
Sensor
Boost
Micro
Controller
Buck
Current
Sensor
Battery
Voltage
Sensor
Temp.
Sensor
XBee
XBee
MCU
Inverter
Solar Panel
47.3 in
Parameter
Siemens SP75
Rated Power
75 W
Type
Single-Crystal
Rated Voltage VMPP
17.0 V
Rated Current IMPP
4.4 A
Open Circuit Voltage 21.7 V
Short Circuit Current 4.8 A
Provided by Florida Solar Energy Center
20.8 in
Microcontroller
ATmega328P
Parameter
Arduino UNO
Chip
ATmega328P
Digital I/O
14 Pins
Analog Input
6 Pins
PWM Output
6 Pins
Communication
I2C, Serial
Protocols
• Arduino Bootloader
• Open Source
Microcontroller Peripherals
XBee
RX
Temperature
Sensors
SCL
SDA
TX
ATmega
328P
Irradiance
Sensor
D2
A3
A2
Current
Sensors
A1
A0
PWM
Voltage
Sensors
PWM
LCD
TX (D4)
BuckBoost
Circuitry
Current Sensor
ACS711ELCTR-12AB-T
Parameter
ACS711
Sensor Type
Hall Effect
Operating Voltage
3 – 5.5 V
Current Sensing
-12 – +12 A
Operating Temp.
-40 – 85 °C
Voltage Sensor
Voltage Divider
Parameter
Source
Sensor Type
Voltage Sense
Voltage
Divider
PV panel
Voltage
Divider
0 – 21 V
R1
2.7 kΩ
R2
10 kΩ
Output Voltage
0–5V
R2=10kΩ
R1=2.7kΩ Vo
Irradiance Sensor
TSL235R-LF
Parameter
Operating Voltage
Output
Operating Temp.
Light Wavelength
Range
Output Frequency
TSL235R-LF
5V
Square wave
50% Duty Cycle
-25 – 70 °C
320 – 1050 nm
200 – 1000 KHz
Temp Sensor
DS1624
Parameter
DS1624
Operating Voltage
3 – 5V
Temp. Range
Internal Memory E2
Protocol
-55 – 125° C
256 Bytes
I2C
LCD Screen
Parameter
20 x 4 LCD
Communication
Serial
Color
Black on Green
Operating Voltage
5V
Max Current
60 mA
Wireless
Module
Parameter
Xbee Series 1
Protocol
802.15.4
Communication
Serial
Transmitting
Power
1 mW
Outdoor Range
90 m
Frequency Band
2.4 GHz
Operating Voltage 3.3 V
Wireless
Subsystem
Battery
Sun Xtender PVX-420T
Parameter
Sun Xtender
Chemistry
AGM
Nominal Voltage 12 V
Capacity
42 Ah
CCA
40 A
Number of
Charges
1000
Inverter
Cobra CPI 880
Parameter
CPI 880
Output Power
800 W
Surge
1600 W
Wave output
Moderate Sine
Input Voltage
12 V
Output Voltage
109 – 120 VAC
AC Outlets
2
USB
1
3 in.
H-Bridge Topology
Buck-Boost DC/DC
Regulator
• Single Inductor
Buck/Boost Architecture
• Separate Buck and Boost
Operating Modes
• Synchronous 4-Switch
Operation for Higher
Efficiency
• Wide Input Voltage
Range: 4.5V to 40V
• Wide Output Voltage
Range: 12V to 15V
Boost Operation
Buck Operation
MPPT Algorithms
Efficiency
Programming Potential
Difficulty
for “error”
Incremental
Highest
Conductance Method
Complex
Yes
Perturb and Observe
Method
High
Average
Yes
Constant Voltage
Method
Low
Low
No
Perturb and Observe Method
MPP
Power
Pmax
Voltage
Vmp
VOC
Battery Charging Stages
Bulk
Absorption
Float
LCD: LCD.print
Xbee: Serial.write
Start
Sensor Read:
Battery Voltage
Float or
Absorption
Adjust
PWM
Regulated
Power
Delivered to
Battery
Bulk
Sensor Read:
Battery Current
I > I0
I < I0
Increase
Voltage
Decrease
Voltage
Printed Circuit Board
Schematic
Testing: Drawing 4.29 A
5/
10
/2
01
2
4:
5/
48
10
:0
/2
2
01
PM
2
4:
5/
;
48
10
:3
/2
5
01
PM
2
4:
5/
;
4
10
9:
/2
09
01
PM
2
4:
5/
;
49
10
:4
/2
5
01
PM
2
4:
5/
;
50
10
:1
/2
8
01
PM
2
4:
5/
;
50
10
:5
/2
1
01
PM
2
4:
5/
;
5
10
1:
/2
25
01
PM
2
4:
5/
;
51
10
:5
/2
8
01
PM
2
4:
5/
;
52
10
:3
/2
1
01
PM
2
4:
5/
;
53
10
:0
/2
7
01
PM
2
4:
;
53
:4
4
PM
;
20
18
12
4
17.3 V
16
14
12.5 V
10
8
6
3.4 A
2
2.0 A
0
Vpanel(V)
Ipanel(A)
Vbatt(V)
Ibatt(A)
Parts List
Cost per part
Number of parts
Total Cost
Solar Panel
Siemens SP75 75W Module
Loaned
1
$0.00
Charge Controller
Printed Circuit Board (Student Special)
Serial Enabled 20x4 LCD - Black on Green 5V
Sensors
Electrical Circuit Components
Misc Lab Supplies (Bread Board, wire, solder, etc.)
$33.00
$29.95
$14.00
$215.00
$48.00
2
1
1
1
1
$66.00
$29.95
$14.00
$215.00
$48.00
Battery
Sun Xtender PVX-420T
$156.88
1
$156.88
Inverter/Outputs
Cobra CPI 880
$80.00
1
$80.00
Microcontroller
Arduino Uno SMD (ATmega328)
$30.00
1
$30.00
Wireless Components
Xbee Explorer Board
Xbee Module
$24.00
$26.00
1
2
$24.00
$52.00
Mounting
Misc Parts for Mounting (Aluminum, Wheels, etc.)
$108.00
1
$108.00
Total:
$715.83