Solar 7. References…………………………………………………………………………………………………………41 Overview: The goals of this

 

Solar Energy Tracker with Web Server Interface

 

 

 

 

Index

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1.       Overview…………………………………………………………………………………………………………….  3

 

2.       Operational Specification…………………………………………………………………………………….  7

 

3.       Literature…..………………………………………………………………………………………………………. 9

 

4.       Progress………………………………………………………………………………………………………………  19

 

5.       Component List…………………………………………………………………………………………..37

 

6.       Detailed Action Plan ……………………………………………………………………………………………40

 

7.      References…………………………………………………………………………………………………………41

 

 

 

 

 

 

 

 

 

 

 

Overview:

 

The goals of this
project are to:

·        
Design and build a Solar Tracker using a PIC
microcontroller.

·        
Design and build a battery charger function to
be used in conjunction with the Solar Tracker

·        
Design a Web Interface to monitor enrgy output
and provide a control element to Solar Tracker.

Functional Design
Specification:

·        
The coordinates of the Solar Tracker will be determined using
a magnometer. The communication from the device to the PIC will be through I2C.

·        
The time of day will be sent to PIC from RTC through I2C.

·        
The designed printed circuit board will communicate with an
LCD screen and PC GUI using Hyperterminal which will display the coordinates
and energy output of the Solar Panel.

·        
There will be communcation to a Webserver through RS232 and
ESP8266-01 wifi breakout board. This will allow the Energy output of the panel
to be monitored on ThingSpeak datastream on Smart Devices.

·        
A program will be written to:

1.     
Implement RS232 and I2C comms using a PIC MCU.

2.     
Implement RS232 and Webserver comms using and WiFi breakout
board.

3.     
Read in analog values from voltage divider circuit and current
sensing circuit and use these to calculate the energy output of panel.

4.     
Read in analog values from 4 LDR’s and use a motor control
algorithm to turn motors on/off.

Fig 1.1 Main program
operation

 

Fig 1.2 Energy
Measurement program

 

The
energy monitor works by measuring the voltage and current output of the panel.
By multiplying these two values you get the generated power.

P =
U * I 
P= Power in Watt; U = Voltage in Volt; I = Current in Ampere.

By
integrating the Power over time you’ll get the total generated Power.

Voltage
measurement

The
voltage measurement is done by a voltage divider over the panel output. To get
the output range of the panels 0-22V down to a range of 0-5V to protect the
analog-digital-converter of the PIC.

Current measurement

The
current measurement is done by ACS712 hall effect current sensors module.

 

 

 

The aim of this project was to design and build a Solar
Energy Tracker capable of displaying energy output on an LCD and
Hyperterminal/HMI and communicating with a web server for remote access
monitoring. The Solar Tracker will also have a battery charging capability.
(fig. 1.3).

Fig 1.3 Solar Tracker
block diagram

 

 

 

It involved designing 2 PCB boards:

·        
Power board – for taking 17v supply from Solar Panel and
charging a 12V battery. The 12V battery supply is regulated to 5V for
components on main controller board. The 5V supply is regulated to 3.3v for
logic level converter and WiFi module boards.

·        
Controller board – containing PIC microcontroller which provides
interface to:

1.     
Voltage and Current sensing circuits supplied from panel and
battery charging circuit.

2.     
Light dependant resistor circuit which detects the optimum
light intensity and decides on the direction to face the panel,

3.     
Max232 chip provides the serial communication with LCD and
HMI and communicates with ESP8266 Wifi breakout board for web server.

 

PCB boards were developed in Multisim and Ultiboard
programs and printed.

The controller PCB board was designed to have ICSP
(In-Circuit Serial Programming) circuit with 5 pin socket for a PICKit2
programmer. That facilitated PIC microcontroller programming without physically
removing it from the board.

 

This initial report describes the main aspects of the
software (SW), hardware (HW) and mechanical development processes. Firmware
code is developed in the MPLAB program using C programming language.

 

 

 

 

 

 

 

Operational Specification:

1.     
Mode: is used to select whether the energy measurement is
started/stopped by the start/stopswitch on the PCB or by a control character
from the PC GUI (Graphical User Interface).

2.     
A variable contrast function LCD will be implemented via a
pot on the PCB Board.

 

3.     
A reset function will be provided which will allow the chip
to be reset via the MCLR pin of the PIC.

4.     
ICSP (In circuit serial programming) will be provided by a 6
pin header mounted on the PCB.

5.     
The PIC16F877 communicates with the I2C Magnometer, where the
resultant coordinates are displayed on the LCD aswell as a PC GUI using
Hyperterminal. 

6.     
The system has 2 inputs (Start/Stop and Mode) which define
its operation:-

 

Start/Stop:- The SPDT (single pole
double throw) PCB switch provided is used to start and stop the energy
measurement when Mode is set to “Local mode”. This switch has no effect while
Mode is set to “Remote Mode”.

 

Enable:- The PCB jumper is used to
select between “Local Mode” and “Remote Mode”.:-

            “Local Mode” :- In this mode the start/stop on the PCB is used to
start and stop the energy measurement. In local mode, the coordinates are only
displayed on the LCD screen. The Green Led is illuminated while the switch in
the position to start the measurements while the Red Led is illuminated when
the switch position is in the other state (i.e. stop state).

            “Remote Mode” :- In this mode the start/stop switch on the PCB has no
effect. A control character/string from the PC GUI is used to start the energy
measurements and data is sent to the webserver upon successful connection to
WiFi, while a different character/string is used to stop the measurement. The
Green led is illuminated while measurements are active and the Red Led is
illuminated when measurements have ceased. In this mode, the LCD screen must
display a message to the operator “REMOTE MODE”.

7.     
A 2-way terminal connector is used to supply 12V to the PCB
board from a power supply. A 5V volt regulator (7805) is used to step the 12V
down to 5V. Also a 10uF decoupling capacitor is used to decouple the 5 Volt
output.

8.     
The PIC16F887 is run off a 20MHz Crystal Oscillator.

9.     
A 16 pin straight wire-to-board connector is used to connect
to an external 2 x 16 LCD display, while a 10Kohm trim pot is used to allow
contrast adjustment on the LCD screen.

10.  A 9 pin D-type PCB mounted
connector is used for interfacing to the PC via RS232 with a null-modem cable.

11.  2 tests points provided on
the I2C lines for the PCB,will allow oscilloscope measurements to be taken on
the SDA/SCL signals.

12.  There will be 5 modular
component boards connected to the main control board;

·        
ESP8266 ESP-01 ESP01 WIFI Module – This is a UART to WiFi module with a
built-in TCP/IP stack used to connect the PIC to internet.

·        
GY-271
HMC5883L Triple Axis Compass Magnetometer Sensor Module – This is a digital compass
used to send coordinates to PIC through I2C.

·        
DS1307 I2C RTC
Real Time Clock AT24C32 Board Module – This is used to send time of day to PIC
through I2C.

·        
ACS712 Current
Sensor Hall Module 20A Range – This is a current sensor based on the Hall
effect which is connected to the ADC of the PIC to detect current generated by
the solar panel.

·        
Mini Motor Drive Shield Expansion Board L293D Module – L293D
is a typical Motor driver or Motor Driver IC which allows DC motor to drive on
either direction. L293D is a 16-pin IC which can control a set of two DC motors
simultaneously in any direction. It is used to drive the 2 linear actuators in
this project with outputs sent from PIC.

 

13.  There
will be 3 modes of operation using:

·        
LDR circuit and algorithm to determine optimum
light intensity and panel position.

·        
Digital compass and Real time clock to determine
position of sun at time of day.

·        
Energy output of panel used to determine optimum
light intensity and panel position.