solar panel monitor systemsenior design final presentation april 22,2010 group #2 department of...

Solar Panel Monitor System

Senior Design Final Presentation

April 22,2010April 22,2010

Group #2

Department of Electrical Engineering and Computer Science

Members

� Benjamin Brindle – EE

Devin McLean – CpE� Devin McLean – CpE

� Robert Parrish – EE

Senior Design Final Presentation - Solar Panel Monitor System 2

Project Purpose

The Solar Panel Monitoring System provides a low cost means to monitor solar panels wirelessly through the World Wide Web that will cut cost in maintenance and installation.


RequirementsAll objectives are derived from the requirements handed down to us from QuickBeam

Energy:

� Antenna ability to transmit minimum of 0.1 mile

� Low cost components less than $150 for prototyping

� Must be able to tolerate all environment conditions -10C to +70C

� Store enough power for more than 24 hours

� Last as long as the life of the solar panel approximately 20-30 years

� Report data at least every 15 minutes

Reasons QuickBeam Energy is interested in this device:

� A cost-effective way to monitor their solar arrays from any location

� Gives their customers the satisfaction of seeing the power they are saving from their home computer

� Gives them the ability to troubleshoot their solar panels, more specifically the ability to narrow down the location of the panels that are not performing correctly

� To do their own market research to see which panels are performing better

� The data to assess the life-cycle of their solar panels and make future decision of the purchase of panels

� Free up regular maintenance personnel to do other jobs


Return of Investment

� With remote and wireless monitoring, solar panel problems can be prevented before costly maintenance

� Maintenance costs about $2,000 per residential installmentresidential installment

� ROI = ($2,000-$164.74)/$164.74 = 11.14

� Therefore, ROI = 1114% return

2nd Annual UCF - Progress Energy Symposium in Renewable & Sustainable Energy

Project Outline


BASE STATION

Base Station

� The base station is the device that receives data from the solar panel sensor and outputs it to a webpage.

� It is assumed that the base station has access to an AC power source and an Ethernet cable for Internet AC power source and an Ethernet cable for Internet connectivity.

� The base station is capable of:

� Wireless Data Reception

� Data Storage

� Data Handling

� Data Output


Base Station Implementation

� The base station is composed of an Asus WL-520GU router.

� It is connected to a D-Link ANT24-0700 2.4GHz 7-dBi omni-directional antenna for additional range.range.

� The antenna boosts the base station’s transmitting power to approximately 25.5 dB.

� The router is operated by DD-WRT, which is a highly customizable Linux based open source firmware.


Base Station Implementation


Wireless Data Reception

� Since the base station is a router, the solar panel device connects to the base station’s Wireless Local Area Network (WLAN).

� While connected to the WLAN, the solar panel device establishes a telnet connection to the DD-WRT’s telnet server.server.

� Throughout the entire time that the solar panel device is powered on, the base station receives new data every 15 seconds through the telnet connection.


Telnet Server


Data Storage

� The base station has the capability to store up to 2GB worth of solar panel device data.

� Each data insertion consists of four separate entries of 13 bytes of time, current, voltage, and power.

� Example entry: 11.321

� The base station receives data every 15 seconds.� The base station receives data every 15 seconds.

� Data storage can continue for 2868 hours, or 119 days.


Data Handling

� The data received by the base station is handled by both parties.

� First, the solar panel device inserts the time, current, voltage, and power data into log files via telnet commands.

� Second, the base station uses a shell script to convert the data into a webpage.

� This shell script is executed every 15 seconds via a telnet � This shell script is executed every 15 seconds via a telnet command from the solar panel device.

root@DD-WRT:~# /bin/sh/solar.sh

Shell script execution:

rm index.htm more v >> index.htm

more v.txt >> index.htm more h >> index.htm

more p >> index.htm more t.txt >> index.htm

more p.txt >> index.htm more c >> index.htm

more f >> index.htm more c.txt >> index.htm


Data Output


SOLAR PANEL DEVICE

CURRENT SENSOR

Current Sensor Choice

� Hall Effect Sensor measures flow of current by being in proximity to conducting deviceconducting device

� This is an advantage because no direct connection to the

circuit is necessary.

Senior Design Final Presentation - Solar Panel Monitor System20

Calculations for Power

o Equation for calculated current from

transducer: I= Vout – Vref

G

� I in amps, Vout in millivolts, Vref in millivolts and G in millivolts / amp

� G is the sensitivity with a typical value of 25.8 mV/A with a standard deviation of .4 mV/A


Sensitivity as a function of distance from primary conductor.


Current Sensor

Model: FHS 40-P KIT 9


SOLAR PANEL DEVICE

EXPLORER 16

Solar Panel Device Explorer 16

� The solar panel device microcontroller is responsible for:

� Reading data from the current sensor

� Transmitting the data to the base station wirelessly

� The Explorer 16 Development Board, which comes with the PIC24FJ128GA010 microcontroller from Microchip, is used to perform these tasks.perform these tasks.

� This setup was chosen for the following features:

� External 5V/ground supply for current sensor

� Easy to interface with microcontroller’s pins

� SPI interfacing for wireless module

� C compiler

� Analog to Digital Converter

� 16 MIPS


Solar Panel Device Explorer 16

PIC24 MCU

ADC Inputs

Senior Design Final Presentation - Solar Panel Monitor System

ZG2100M

26

Reading Sensor Data

� The solar panel device reads the current sensor’s measurement as an analog signal.

� The PIC24 uses its third analog to digital conversion channel to convert the analog signal to a digital and numerical value.


Transmitting Sensor Data

� The solar panel sensor will communicate with the base station via the ZeroG ZG2100M module.

� Small size: 21mm x 31mm x 3.7mm

� SPI interface to Explorer 16/PIC24

� Supports standard IEEE 802.11b wireless� Supports standard IEEE 802.11b wireless

� Data rate of 1 & 2 Mbps

� Supports WEP, WPA, and WPA2 security

� Runs on 2.7 – 3.6 volts, 0-70° C



� TCP/IP Stacks and Radio Drivers programmed in C are used for Wi-Fi functionality.

� The drivers are configured to connect to the base station’s wireless network when power is supplied



� Once connected to the base station’s WLAN, the solar panel device will establish a telnet connection.

� It will transmit the current sensor’s data and other calculations every 15 seconds.

� Four total data insertions every 15 seconds:

� Time, Current, Voltage, and Power� Time, Current, Voltage, and Power

� An example telnet command:

� echo “11.321
” >> c.txt

� The echo command copies the text within the double quotations to the screen, and the >> command takes the copied text from the screen and appends it to the filename that follows.


BUCK CIRCUIT

Buck Regulator

� A buck converter was chosen because linear regulators are inefficient. This would allow us to maintain efficiency as voltage is being converted.

Using a wide range linear power regulator, � Using a wide range linear power regulator, the efficiency would be 5/60 or 8.33% at maximum yield. Using switching technology, the efficiency can be kept around 70%


Buck Regulator

� We chose the LM2575 HV adjustable Buck

� Range of 1.5- 60 volts

For prototype using 2 panels � For prototype using 2 panels this range is acceptable

� The circuit to the right controls the feedback loop of the buck, which sets the output voltage


Buck Schematic


Buck PCB Layout


Buck Implementation


BATTERY CHARGING

CIRCUIT

Battery Selection


Battery Equations

� Buck Circuit .01 A

� Current Sensor 11mA

� PIC24 Development Board with ZeroGWireless Module .03A

� Battery Charger-Float mode (battery maintain) .04 A, Charge mode .5 A

� Maximum consumed- .55 A


Acid Etching

We decided to etch our own boards and used an Acid Etch technique. First, we printed the reverse image of the board onto laminated paper, then used a iron to make the then used a iron to make the toner adhere to the board. Then proceeded to acid etch the board. The process took us about 2 hours from start to finish.


Solar Panel Battery Charger

� Design Considerations

� Charge a 12 volt battery

� Take in to account ambient temperature and overchargingtemperature and overcharging

� Be able to tell when the battery is charged and enter float mode or switch off

� Have minimal draw off the solar device, reducing power consumption


Solar Panel Battery Charger

� We used the LM317 to adjusts the Voltage for charging

� A SOC feedback loop was constructed that consists of the LM317 and the potentiometer which allows us to change the output voltage.

� An LM334 acts as a comparator to read when battery has reached charge and changes to a float mode to maintain reached charge and changes to a float mode to maintain battery and prevents overcharge

� A diode array, which takes advantage of the thermal characteristics of PN diodes, is used to lower or raises the reference terminal of the LM317 by 22mV every 1 degree C during float mode. This fulfills our Automatic ambient temperature compensation requirement.


Battery Charger Schematic


Battery Charger PCB layout


Battery Charger Implementation


LT1510 Battery PCB Layout


LT1510 Battery Charger Implementation

When we initially decided to use the LT1510 we were using a lithium-ion battery. Deciding that the capacity of these batteries were not meeting our requirements we switch to a lead acid battery. The LT1510 capabilities are overkill for this type of implementation, and it was decided to go for a simpler configuration.


TESTING


Testing

Several issues arose and were resolved during the testing phase of senior design.

Issue 1: Solar Device and Current Sensor

� Data recorded was not getting properly sent form the current sensor to the A/D converter, and we were getting bad readings on the website.

Issue 2: Buck Circuit

� The original design for the buck circuit was surface mount parts and proved too difficult to test. Therefore, a through hole alternative was used.

Issue 3: Battery Charge Controller

� At first, the battery charger did not appear to be charging the battery correctly. This was due to the solar panels not producing enough current.


ADMINISTRATIVE

CONTENT CONTENT


Milestone ChartAugust September November December Janurary February March April

Fall Semester (Senior Design 1) Spring Semester (Senior Design 2)

Solar Device Circuits Construction

Research Different

Base Station SolutionsBase Station Code Completed

Router

Selected

Website CompletedTelnet Finished

Research and Design Build Prototype

Research

Microcontrollers

Design Base Station

Design Solar Device

Part Acquisition

Timeline

Construct

Enclosures

Senior Design 1 Paper Due

PresentationFinal

Presentation

Research Wireless

Solutions

Base StationSolar Device Interoperability

Battery Selection

Microcontrollers

Design Wireless

Functionality

Microcontroller

Selection

Buck Circuit

Battery Charger Circuit

Current Sensor

Testing

Individual Action Item


BudgetPart Name Company Amount

12V 12AH Battery Batteries Plus $47.91

Capacitors/Inductors/Resistors Digi-Key $39.56

Cap cer 2.2UF 100V Digi-Key $40.07

FHS 40 PCB Kit Digi-Key $47.99

ZeroG Development Kit microchip direct $209.29

OptiMOS 2 Pwr-Tranc Mouser Electronics $4.45

Solder Parts/5V reg/16pin IC/Forceps Radio Shack $19.84

Soldering Gun Radio Shack $95.83

capacitors Skycraft Parts & Surplus $6.82

Ring 16-14 and 1/16 Tin Bit The Home Depot $4.22

9V DC 1A Power Supply ebay $5.53

9V DC 500mA Power Supply ebay $10.70

Pickit 2 ICD Interface microchip direct $19.72

Pickit 2 microchip direct $34.59

Explorer 16 Development Board Newark $143.82

Battery Charger Parts Digi-Key $61.79

Flux/misc comp Skycraft Parts & Surplus $32.70

PIC24 Prototyping Board microchip direct $27.68

Pictures from presentation board Kinkos $16.00

Parts for battery charger Digi-Key $63.78

Parts for buck Digi-kKey $58.35

Progress Energy Symposium board/materials Staples $23.25

Enclosure Cases Radio Shack $21.44

High Wattage Resistors Skycraft $6.00

More breadboards Radio Shack $9.67

Total = $1,051.00Senior Design Final Presentation - Solar Panel Monitor System 54

Work Distribution � Ben

� Microcontroller Research

� Buck Circuit Design

� Testing Buck Circuit

� PCB transfer

� PCB Assembly

� Devin� Wireless/Base Station Research� Wireless/Base Station Research

� Developed Code for Base Station and Solar Panel Device

� Set up website and Telnet client

� Testing of Code

� Sensor Testing

� Robbie� Battery/Charger Research

� Battery Charger Circuit Design

� Testing Battery Charger

� PCB Design

� Assisted in PCB assembly


QUESTIONS?


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