The system was designed to generate electricity around 200 Watts from mono crystalline Solar panels. It follows SUN to generate maximum amount of power, typically following SUN produces approximately 25% more energy than fixed Solar panels. Grid Tie inverter was used to feed electricity back to Grid.
Principle of Operation:
This system utilizes 4 sensors EAST, WEST, NORTH and SOUTH. Sensor feedback is fed to microcontroller which processes sensor data to measure the intensity of the SUN light. The difference is calculated and microcontroller initiates motion to balance the output of pair of sensors EAST/WEST and NORTH/SOUTH. The microcontroller keep on looping this cycle after few seconds to keep aligned with SUN. The panels automatically go back to EAST home location in dark.
The system also keeps track of the temperature, battery voltage etc. The data is sent back to host computer which collects and displays current stats on web a page.
There is an option to lay solar panels horizontal, this is usually required when there is a storm or high wind.
This can also be aligned vertical and can send back to rest in east direction so that next morning it starts following SUN from east direction.
Design:
I used Stellaris LM4F120 ARM MCU based Launchpad from TI (Texas Instruments). For east west rotation I used stepper motor with drive bought from SainSmart stepper driver board. For North South motion, I used linear actuator from servo city. This actuator uses 12V DC motor with potentiometer feedback. MCU reads potentiometer to keep track of linear actuator position.
System reads temperature and adjusts FAN speed which keeps the airflow inside the box to maintain temperature.
FAN runs at full speed when temperature exceeds 80 Deg F.
Whole system runs on 12V battery which in turn is charged by solar panels.
DC voltage produced by panels are fed to MPTT charge controller to charge battery and also connected to 300Watts Grid TIE inverter.
EAST/WEST motion uses stepper motor with Neugart 120 heavy duty planetary gear box. I removed flywheel from an old treadmill to make the base for holding solar panels.
All screws used are stainless steel and all enclosure panels are made from Aluminium to avoid corrosion from weather conditions.
Servocity Linear actuator is weather proof with rating IP65.
Status packet data is sent to host computer every few seconds. I used Lantronix serial to ethernet module to talk to host computer using TCP/IP protocol.
The host computer running Fedora linux hosts Apache webserver
PHP/Javascript code interacts with main controller inside housing to get sensor updates and displaying on client browser.
Please see the screenshot below.
http://www.youtube.com/watch?v=XWHsqVGJYRM&feature=youtu.be
The following are few steps taken to make this system.
1. Ground preparation for Panels. Selected corner of house where sun light is mostly available. Concrete platform for the system. See pictures below.
 |
| Floor preparation |
 |
Neugart heavy duty Gear Boxto hold Panels.         |
