Welcome to my solar charge controller tutorials series.I have posted two version of my PWM charge controller.If you are new to this please refer my earlier tutorial for understanding the basics of charge controller.
This is project is entered to " 2015 Hackaday Prize ".If you want to support me and see the project in a new level,please follow and give skulls to my project @ hackaday.io.This will be very helpful for me.
This instructable will cover a project build for a Arduino based Solar MPPT charge controller.It has features like: LCD display,Led Indication,Wi Fi data logging and provision for charging different USB devices.It is equipped with various protections to protect the circuitry from abnormal condition.
The microcontroller used is in this controller is Arduino Nano. This design is suitable for a 50W solar panel to charge a commonly used 12V lead acid battery. You can also use other Arduino board like Pro Mini,Micro and UNO.
Now a days the most advance solar charge controller available in the market is Maximum Power Point Tracking (MPPT).The MPPT controller is more sophisticated and more expensive.It has several advantages over the earlier charge controller.It is 30 to 40 % more efficient at low temperature.But making a MPPT charge controller is little bit complex in compare to PWM charge controller.It require some basic knowledge of power electronics.
I put a lot of effort to make it simple, so that any one can understand it easily.If you are aware about the basics of MPPT charge controller then skip the first few steps.
The Maximum Power Point Tracker (MPPT) circuit is based around a synchronous buck converter circuit..It steps the higher solar panel voltage down to the charging voltage of the battery. The Arduino tries to maximize the watts input from the solar panel by controlling the duty cycle to keep the solar panel operating at its Maximum Power Point.
Specification of version-3 charge controller :
1.Based on MPPT algorithm
2. LED indication for the state of charge
3. 20x4 character LCD display for displaying voltages,current,power etc
4. Overvoltage / Lightning protection
5. Reverse power flow protection
6. Short Circuit and Over load protection
7. Wi Fi data logging
8.USB port for Charging Smart Phone /Gadgets
Electrical specifications :
1.Rated Voltage= 12V
2.Maximum current = 5A
3.Maximum load current =10A
4. In put Voltage = Solar panel with Open circuit voltage from 12 to 25V
5.Solar panel power = 50W
This project is consists of 40 steps.So for simplicity I divided the entire project in to small sections.Click on the link which you want to see.
1. Basics on MPPT charge controller
Updates as on 16th June 2015
Version-4 Design Ideas and Planning
After my version-3 Charge Controller became popular on web,I received mails and comments with request for making a higher rating Controller. So we are designing our Version-4 Charge Controller which is more advanced, greater capacity and useful more potential applications.When the project complete, it should be useful for off grid electricity users, control of autonomous street lights and signs, and many other applications that need medium power levels and efficient reliable operation
For all the ongoing activites click here
Problem in V-3 :
During my prototyping, I have faced a critical issue.The issue was that when I connect the battery to the controller,the connection between the battery and the switching ( buck converter ) become very hot and then MOSFET Q3 burn out.It was due to shorting of MOSFET-Q3. So Current flows from Battery -MOSFET Q3- GND which is unexpected.
To solve this problem I have asked to viewers. After taking suggestions from all, Keith suggestions really works for me.So I have modified few things.
Rectifications / Changes :
As per Keith suggestions
Modification in MOSFET Driver Circuit :
1. With the existing circuit, if the panel voltage is zero then the IR2104 has no VCC input. This may make its behaviour unpredictable.As per data sheet, the driver VCC should be in between 10 and 20 Volts for "proper operation".
2. It means the driver will always be working, and so there is a positive control over the switching MOSFETs at all times.
3. The voltage from the solar panels has been specified as up to 25 volts, which is a bit more than needed to connect a standard 36 cell solar panel. The voltage doubler circuit that generates the Vb voltage for the driver will turn that into 50 volts, which in turn will put 25 volts onto the Source-Gate interface of both Q1 and Q2. The maximum rating of this interface is 20 volts, so either of these FETs may become unreliable with a high solar panel voltage of more than 20 volts.
4. Using the battery for Vcc of the driver means that Q1 and Q2 both only have Source-Gate voltages equal to the battery, which is comfortably within the 10 - 20 Volt range of these MOSFETs.
Changes : Powering the MOSFET driver IR2104 from battery terminal ( 12V ) instead of solar panel ( earlier ).
If anyone making this controller, make this changes and test it. If you have any test results / suggestions, comments it below.