Component choices and Software Development

28^th Nov 2012

Week five:

The Vishay bpw24r photodiode is suitable for the 3 sensors required in this tracking device, this photo sensor will be biased with a voltage and calibrated to the micro controller, this component  has a small aperture of 12 degree’s so it is more directional and will not pick up the incidental light (noise frequencies) that are undesirable as readily.
Other components like the BJT’s have been chosen so as to allow for enough current to flow to power the movement of the servo’s these are 2N2222, they have a max current of 0.6 amps collector to emitter so these can be limited to the required current of around 0.2 amps.

Ref. http://www.engineersgarage.com
/electronic-components/2n2222-transistor

Ref. http://us.100y.com.tw/ChanPin.asp?MNo=57169

Software and Testing:

As the flow diagram is satisfactory for the function of the tracker the writing of the software is to be started  using the Arduino UNO R3 and a test circuit is to begin.

Ref. http://www.arduino.cc/en/Main/arduinoBoardUno

Sensors and Servo's

25^th Nov 2012

Week Four:

With the block diagrams and software flow charts completed to prototype level a clearer picture has emerged as to the needs of the circuit and software.

The sensors:

The following reasons need to be addressed for the type of sensor to be used.

• A fast response time even at low voltages. 

• Visible light is the most energetic for solar panels which operate between(400 - 1100 nm),  Therefore the light spectrum of this device needs to cover visible to nearly infrared frequencies.

•  A shallow angle of sensitivity to be more directional and therefore less susceptible to noise.

• Low current suitable for interfacing with the Micro-controller.

·         Set as a common collector this will provide low voltage levels at low light levels suitable for the A/D of the Micro-controller.

Main control software.

The motors (servos):

As servos are the be used and there power supply to be turned on and off switching transistors will have to be used to protect the Micro-controller from the high currents needed for the servos, also protection diodes implemented across the power supply of the motors to prevent damage to the switching transistors from the collapsing coils in the motors.

The signal lines may also have to be protected depending on the current drawn by them, the signal lines will be programmed to move the servos as shown with the software flow charts.

Servo control software.

Block diagram and software flow chart.

http://pvsuntrac3.blogspot.ie

20^th Nov 2012

Week Three:

In the lab further investigation was done into photodiodes as to functionality and response frequencies, it was decided that light dependant resistors (LDR) are to slow in their response time to be considered so photo sensors or infrared sensors would be better suited to the overall design.

The best way forward from this point was to create the circuit block diagram and a software flow chart so as functionality of the design can be validated and after when the goals are outlined by these methods investigation into the actual components that will be will be used. These are to be readied for the following week’s lab for the supervisor.

Further Research

Week Two:

On reflection over the week the ideal prototyping platform for development of this project would be the Arduino as it is easily configured and the software is familiar as it is very like the C programming language, the Atmel micro controller could then be incorporated into the PCB design for the finished product.

In lab further research was sought for efficiencies and studies as to the drop off in efficiencies at different angles to the sun however little could be found on the nets about it that was freely published.

The Light spectrum was investigated. Ideas about setting a calendar and a position tracker in software to track its position were investigated. However for the moment a simple zero position switch can be implemented and this can be used to position the tracker to the east for the next day.

http://cholla.mmto.org/lights/spectra/

A sensor is needed to analyze the sky either by comparison using light dependant resistors or by perhaps infra red sensors further investigation is needed for the method.

The motor also will have to be discussed as one has to rotate more than 180 degrees and the other maximum of 90 so a stepper and a servo might be ideal also the servo could be useful for a feedback software update in a future development for better sensitivity or even develop a software readout of position (the latter is not initially going to be used).

first week research ideas ????

3^rd year project Pv. Solar panel tracker.

Author Aiden Sweeney

B00045183

6^th Nov 2012

Week one:

 In week one on presentation of the assignment some research was conducted into the origins of the photo voltaic effect, This was first observed by Aleixandre Edmond Becquerel (1820 – 1891) a French physicist in 1839 ( http://www.solareworld.com/blog/green-community/solar-history-alexandre-edmond-becquerel).

Much research has been conducted since to the development of modern photo voltaic solar panels.

Leaving the state of play in efficiencies of conversion around 15%for domestic panels to about 40% for use in satellites where this is obviously more expensive using multilayer panels.

As the world thirsts for power it makes sense to maximise the capacity of solar cells and this sort of tracking can be an efficient method of maximising output.

Large solar arrays like the one at Nellis Air force base in the USA implement such tracking devices and on its implementation in 2007 it was expected to save the USAF a million dollars a year

http://www.nellis.af.mil/news/story.asp?id=123079933

This image or file is a work of a U.S. Air Force Airman or employee,
 taken or made during the course of the person's official duties. As a work of the U.S. federal government,
the image or file is in the public domain.



Pv panels are most efficient when they are positioned at 90 degrees to the sun, so a quick reflection at this point one motor to rotate the panel is ideal if it is placed on the equator however for temperate climates the maximum arc of the suns rotation in midsummer is far greater than 180 degrees so controlling accurately that and a horizontal of a maximum of 90 degrees the use of a micro-controller for two motors should be needed.