Why We Need Solar Tracker System ?
The electricity generated from fixed tilt angle solar array is less efficient throughout the day as the solar array is not facing the Sun directly (optimum angle) all the time. Sun moves 15 degrees every hour from East to West across the equator. The larger the angle difference between sunlight incidence and solar panels facing, the larger the losses based on cosine formula.
Secondly, due to the tilting of earth’s axis of rotation, the Sun also moves with variation ±23.5° in North-South direction across equator throughout the whole year. It will have slight losses even fixed array facing the optimum angle. East-West sun angle movement is a daily basis thus affecting the total production more significantly compared to North-South deviation from optimum angle which is movement on yearly basis. To understand how the Sun moves, we need to understand the Sun path diagram. The sun path diagram is a diagram describes the location of the sun and movement relative to latitude location.
100Wp Solar Panels
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DC Energy Meter
DC Energy meter display important measurement units such as voltage, current, power and energy. It is very useful to troubleshoot or analyse an electrical or project performance. Grab one at our affiliate link here !!!
MPPT Solar Charge Controller
MPPT Solar Charge Controller is a regulator that protect battery while charging and discharging. It also maximize the power generation of the Solar Panel. Kindly support us by getting at our affiliate link here !!!
What Is A Solar Tracking System ?
A Solar Tracking system rotates solar panels to face the sun all the time to increase power generation. The tracker helps to minimize the angle of incidence between incoming light and the panel, thus increases the amount of daily energy. It consists of a tracking algorithm (programming or mathematical coding in micro-controller), Control Unit (micro-controller), positioning system (the method – electrical / hydraulic / compressed gas), the driving mechanism (linear actuator / stepper motor), sensors (photodiodes / GPS astronomical tracker), and Sensing device (pyranometer, anemometer, photo resistor).
The 2 Common Solar Tracker Technologies
The solar tracker consists of two technologies: real time light intensity sensor or use astronomical calculation. Real time light intensity has a light sensor device attached at the side of the tracker to trace the sun direction using intensity differences concept.
Astronomical calculation is another technology using GPS coordinate and local time based on the site location to superimpose into the sun path algorithm thus purely using mathematics calculation without physical sensor. Solar tracker with light sensor is more common available in the market as it does not requires sophisticate control unit and settings.
Today’s blog is talking about the local time based Astrological method. It is a method that do not require Photo Sensors but only requires your local time to track the sun. With the help of Blynk App, we can let the micro-controller knows what time is your local time so that it superimpose with the Sun Path Database that is stored inside the micro-controller (NodeMCU). The advantage of using this method is simplicity with minimum wiring of installation (because without sensors). However, we need the internet to work all the time. It requires to communicate with Blynk Server to get the Time parameter input. This is another fun project to do any it is something more special compare to regular sensor-based solar trackers.
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Fixed Tilted Angle
Fixed Tilted Angle Solar Array is without moving parts. It has the largest conversion losses due to large angle difference between Solar Array facing and sun Direction. Assuming the Solar Array is facing at Optimum Angle, which the tile angle is equivalent to Latitude Angle of the site, From the Sun Path we can see, due to fixed location, the Solar Array facing is symbolized by a center Red Dot. The largest angle difference between the sun direction relative to Solar Array happens during Dusk and Dawn, thus has highest power conversion lost.
Single axis tracker
Single axis tracker can rotate panels in one degree of rotation which normally applied to East to West direction. It tilts solar panels to face East when sunrise, top at noon and West when sunset. The single axis tracker generally can increase additional daily production up to 25-30% compared to fixed tilt angle array. Single axis tracker normally tilted to optimum angle in North-South direction for maximum harvest. It is mostly used in utility scale PV power system as it is more cost efficient compare to dual axis. However, due to axis of rotation of the earth, there are some months the Sun Travel further away from Optimum Angle which could up to about 9% lost at max (23.5 degree difference worst case) on that particular time or month. However, on average, losses is just only about 5% due to angle of difference throughout the year.
Dual axis Solar Tracker
Dual axis Solar Tracker has two degree of rotation. Besides East and West tilting, it also has North and South tilting, which completes the coverage of the whole sun path direction. Dual axis continually facing the sun direction without large angle difference. Compared to single axis tracker, it may increase annual generation by another 5-10%. The add-on efficiency is relatively low due to low angle difference in North-South direction (only about ±23.5° deviation from optimum angle) which is on yearly basis compared to East-West direction (±90° deviation) which is on daily basis. Dual axis tracker is preferable for higher latitude countries where sun position changes dramatically between summer and winter. However, it has low demand compared to single axis tracker due to cost inefficiency. It is only used for application with high accuracy needed such as parabolic or mirror concentration for thermal plant.
So in this example, we will prefer DIY Single Axis Solar Tracker. It is more cost effective and Simpler to do.
The NodeMCU micro-controller is similar to Arduino micro-controller board. It is compatible with Arduino IDE software and is built-in with the ESP8266 module which can be connected to the internet. You can grab some at our affiliate link here !!!
Node MCU Micro controller Base
The based below the Node MCU can provide more flexibility on the connection ports to support more sensors. Besides, it also has 12V input port and able to provide 5V power supply to support the sensors. Support us by purchase it from our affiliate link here !!!
High Torque Servo Motor
Servo motor is a very precise on angle of rotation. It has position memory rather than typical DC motor thus Servo Motor is suitable for Solar Tracking System. High torque is required depending on the solar panels size and weight. Grab it here !!!
Warning : The Servo motor Gear is small, make sure to get high torque and industrial type if using on typical frame solar panel. Kindly determine whether it can support the weight of the solar panel.
DC-DC Buck Converter Module
DC to DC buck converter allows a wide range of DC input voltage to be step down and regulated to desired output voltage. It mostly applied on Solar DC direct application. You may need a multimeter to measure the voltage output by adjusting the trimpot. Grab one at our affiliate link here !!!
So in this project, what we will be using are :
- 1 x nodeMCU micro controller board
- 1 x DC-DC Step Down Converter
- 1 x High Torque (in this example is 20kgcm) Servo Motor.
- 2 x Pillow Block Bearings (20cm for 15mm pipe)
- Structural, Wiring and its accessories
Warning !!! The video just for demostration purpose only. The Solar Tracker must have an independent power supply (or at least connected to battery source for off-grid system or connected to adapter if there is grid power available to prevent coding error of the Tracking System during weak sunlight.
Ferrule Lugs and Crimper Set
Ferrule lugs are used at terminals for tight and secure connection. Besides, it also prevent stranded cables accidentally touching adjacent power line that may cause short circuit. Grab 1 at our affiliate link here !!!
- DC-DC converter from Solar Panel to NodeMCU base
- 5V from NodeMCU base to Servo motor 5V (Red)
- Gnd from NodeMCU base to Servo motor Gnd (Chocolate)
- D0 (GPIO 16) from NodeMCU base to Servo motor PWM (Orange)
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Software Step by Step Guideline
The software part will be divided into 2 parts: 1) the smart phone web interface Blynk App and the 2) programming part using Arduino IDE Software.
- Download Blynk App on your smart phone (Google Play / AppStore).
- Open and create an Account on Blynk App.
- Add New Project (see below section)
- Blynk will send a Auth Token to your email specifically for this project.
- At your project main page, swap to the left to open Widget Box.
- Add Widget : Value Display Widgets & Real-time Clock Widget
- Add other Widgets based on your desire:
Virtual pin V1 = Maintenance / Horrizontal Button (SWITCH or PUSH Type)
Virtual pin V2 = Energize Button for automate (PUSH Type)
Virtual pin V3 = Value Display (Show angle)
Add a Real Time Clock (RTC) Widget, set your time zone
On Laptop / PC
- Install Arduino IDE Programming Software (If you do not have the software, click here to download)
- Install Node MCU Board Manager for using Node MCU in Arduino IDE Programming Software (see below section)
- Install Node MCU ESP8266 Library for using Wifi codes in Node MCU (see below section)
- Install Blynk Library for enable the Node MCU using Blynk server (see below section)
- Install Time Library for time related programming codes. (see below section)
- Copy Auth Token from the email, note down the Wifi name & password.
- Upload the code to Node MCU Board.
Install Node MCU Board Manager
If this is the first time you are dealing with NodeMCU, you need to add NodeMCU board manager file into the IDE software so that the software can support the Node MCU board. To add the Support File, open Arduino IDE Software, go to files>preferences>Additional Boards Manager URLs, paste this link http://arduino.esp8266.com/stable/package_esp8266com_index.json to the black space and click OK. Go to Tool > Board > make sure the board is showing NodeMCU 1.0 (ESP-12E module).
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Install ESP8266 Wifi Library
If this is the first time you are dealing with Wifi programming, this ESP8266 Wifi Library file is needed to be installed to the Arduino IDE Software so that it can understand the programming function. Go to Tools > Boards > Boards Manager and download the ESP8266 library by ESP8266 Community
Install Blynk Library
If this is the first time you are dealing with Blynk server, this Blynk Library file is needed to be installed to the Arduino IDE Software so that it can understand the programming function. Go to Tools > Boards > Boards Manager and download the Blynk library by Volodymyr Shymanskyy
Install Time Library
In order to do programming codes related to Real Time Clock, you need to install the Time Library. You can download the .zip file here which I also downloaded from Github. Kindly download the .zip file on desktop. To download the Time Library file, open the Arduino IDE Software. Go to Sketch > Include Library > Add .Zip Library > Select the Downloaded Time-master.zip file. That’s it.
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