This document summarizes a solar tracking and power generation project conducted by students at UC Santa Barbara. It discusses how solar tracking can maximize the amount of sunlight collected and describes the key components of the system, including Fresnel lenses, photovoltaic cells, thermoelectric generators, microcontrollers and motors for autonomous solar tracking. Performance results are provided, showing a theoretical power of 6W but actual generation of 1.94W, with a net energy production of 0.142Wh over 5 minutes. Areas for further improvement are also noted.

1. Matthew Honea
Alex Marsh
Daniel Dicarlo
Richard Schapker
University of California Santa Barbara
June 2010

2. • 89 Petawatts of sunlight reaches the earth’s
surface
• Humans consume 15 Terawatts, about 1/6000
of what reaches earth
• Solar receives the least funding for research
when compared to other energy sources

3. • Need maximal sunlight on lens to focus power
to thermo module
• Rayleigh scattering will cause the sunlight to
diffuse at non-direct angles
• Solar tracking will give us maximal beam
power

6. • Creating a fully functional autonomous system
for solar tracking
• Establish communication links and processing
information gathered from thermocouples,
pyronometers, limit switches and stepper
motors
• Store power collected from the system into
onboard batteries

7. •Both lenses have same focusing power
(Fresnel #1, Plano-Convex #2)
•Picture shows how a Fresnel lens is made
of sections, reducing its thickness but
causes images to be blurred
•Can be made of plastic, has short focal
length and cheap to produce (used in
lighthouses)

8. • Photovoltaic like cool temperatures
• Thermoelectric like hot temperatures
• Maximum efficiency of photovoltaic is about
23%
• Thermoelectric devices have about 5-6%
traditionally. New methods have raised this
number to 12% and above

9. • Photovoltaic technologies cause current when
the photons of the light excite the electrons in
the material to move to a higher energy state
• Thermoelectric current is caused when the
heat source drives electrons in n-type
materials and holes in p-type materials from
the hotside to the cool side

10. •Peltier effect discovered in 1834,
junction between metals absorbed
heat at one end and released heat
at the other
•We want to maximize the
temperature gradient, keeping the
hot side hot and the cool side cool
•Hot side can reach 500 degrees
Kelvin while cool side should remain
at 300 degrees Kelvin

11. ZT is the figure of merit for
a thermoelectric device
defined by:
Where T is the average
temperature, S is the
Seebeck coefficent, ρ is the
electrical conductivity, and k
is the thermal conductivity.
The higher ZT, the higher
the effective efficiency

12. ErAs:InGaAlAsErAs:InGaAlAs

16. • Start by using commercially available
materials (Bi2Te3) using Seedbeck effect
• Two Boxes – Controls and Lens
• Lens will track sun using a series of
coordinates specified by location on earth and
time/date.
• Energy will be stored in lithium-ion batteries

17. • TI MSP430
Microcontroller
• 16 MHz processing
speed
• LCD display
• I/O directly supported
• 16bit A/D conversion
• 512k memory

22. •Steps are controlled
on a grid
•Gears are designed to
move .45 degrees per
step
•Azimuth rotates180°
•Elevation rotates 90 °

28. Theoretical power through system – 6W
Actual Power Generated – (1.3V, 1.5 A) - 1.94 W
Power Sustainability during 5 min period
Motor control energy used – 0.02 W h
Net energy generated – 0.142 W h
---------
Total Energy produced – 20.4 W h/day

29. • Bigger lens attachments
– Replace 11” with 18” and triple the power
• Excess power? Cool something with Peltier
junction
• New Thermoelectric materials
• Combined photovoltaic and thermoelectric
– Separating the wavelength spectrum

31. John Bowers’ Research Group
Richard Schapker
Ilan Ben-Yaacov