CONTENTS• Introduction• What is a Solar Tracker ?• Need for a Sun Tracking System• Condition for Maximum Output• Basic Components• The Working• Applications• Advantages & Disadvantages• Conclusion
INTRODUCTION• EXTRACTING usable electricity from the sun was made possible by the discovery of the photoelectric effect.• Subsequent development of the solar cell, which is a semi-conductive material that converts visible light into a direct current.• Solar arrays, a series of solar cells electrically connected, generates a DC voltage which can be used on a load.
Contd…• Solar arrays are being used increasingly as efficiencies reach higher levels, and are especially popular in remote areas where placement of electricity lines are not economically viable.• For further optimization of these panels solar trackers are being implemented, which enhances the efficiency of panels by 30-35 %.
What is a solar Tracker ?• A solar tracker is a generic term used to describe devices that orient or align various payloads toward the sun.• Example for payloads are photovoltaic panels, reflectors, Collectors, lenses or other optical devices.• The system focuses on the optimization of the electric energy produced by photovoltaic cells through the development of a sun-tracking system.
Need For A Sun Tracking System• From dawn to dusk the sun keeps changing the angle from 0-90 rising and 90-180 declining.• In a year of 365 days the sun moves approximately 22.5 degrees north to 22.5 degrees south of the equator.• We get maximum energy from the sun when - The angle of the sun is degrees - The sun’s position is 0 +/- 5 degrees of the equator
Contd….• For the fluctuation factors mentioned previously, fixed solar panels does not give higher efficiencies.• A tracking system helps the solar panels keep oriented to the sun at the optimum possible angle.• The tracking system improves the efficiency of solar panels by 30% for single axis and an additional 6% for dual axis.
Conditions For Maximum Output• The difference between the incident ray and the reflected ray should be equal to zero, i.e. the rays should be perpendicular to the panel.• The altitude is directly proportional to the efficiency of the system up to a certain limit.• Very clear sky and clean atmosphere contributes a bit more to the efficiency of the system.
Basic Components• The Solar Panel• Stepper Motor• Actuator• Microcontroller• A Display Unit (Optional)• Interfacing Cables
The Working• Interfacing between hardware and microcontroller• Inputs to microcontroller• Controlling constraints
The Inputs• The various positions of the sun over a year for a particular geographical location is given as the primary input to the microcontroller.• The irradiance of the sun for a particular geographical location over a year is the secondary input for the microcontroller.• The real time clocking is enabled in the microcontroller.
Controlling Constraints• The microcontroller is programmed to orient the panel at optimum position against the sun, via comparing to the inputs given.• The microcontroller is set with a lower tolerance for the voltage produced.• If the voltage produced is above the tolerance then it holds the position of the panel.• If the voltage falls below the tolerance, then the panel changes the position in the forward direction.
Contd…• This voltage tolerance varies according to various seasons. Like summer has the highest voltage tolerance value.• A second voltage tolerance is given, so as to switch off the system when it falls beyond the tolerance.• This will help in cloudy and rainy days.• A panel will be reset to its default position at the end of the day and starts again the next day. This is accomplished by a timer & angle limits.
Applications• Can be used for small & medium scale power generations.• For power generation at remote places where power lines are not accessible.• For domestic backup power systems.
Advantages• Solar tracking systems continually orient photovoltaic panels towards the sun and can help maximize your investment in your PV system.• One time investment, which provides higher efficiency & flexibility on dependency over other sources.• Tracking systems can help reducing emissions and can contribute against global warming.• Bulk implementations of tracking systems help reduced consumption of power by other sources.• It enhances the clean and emission free power production.
Disadvantages• Initial investment is high on solar panels.• It’s a bit of difficult for servicing, as the tracking systems are not quite popular regionally.• Moving parts and gears which will require regular maintenance.• May require repair or replacement of broken parts over a long run.
Conclusion• On one hand we can see the worlds energy resources depletion to be a major problem.• On the other hand global warming, which is a major concern.• Switching to solar power, which is clean and green and enhancing its efficiency by using sun trackers is a great option in the near future .
References• http://www.solarpoweristhefuture.com• http://www.scientificamerican.com• http://www.linak.com/products• http://www.thesolarguide.com• http://www.patentstorm.us• http://www.free-power.org• http://en.wikipedia.org• Solar Energy – Principles of thermal collection & storage By S P Sukhatme