1、 Solar Tracker David Crowe, Jeff McCormick, Joel Mitchell, Thomas Stratton, Jeff Schwane December 15, 2005 Duke University Smart House Pratt School of Engineering Abstract The Solar Tracker team was formed in the fall of 2005 from five students in an ME design team, and a Smart House liaison. We con
2、tinued the work of a previous solar tracker group. The task was to design a prototype tracking device to align solar panels optimally to the sun as it moves over the course of the day. The implementation of such a system dramatically increases the efficiency of solar panels used to power the Smart H
3、ouse. This report examines the process of designing and constructing the prototype, the experiences and problems encountered, and suggestions for continuing the project. 1.Introduction Solar tracking is the process of varying the angle of solar panels and collectors to take advantage of the full amo
4、unt of the suns energy. This is done by rotating panels to be perpendicular to the suns angle of incidence. Initial tests in industry suggest that this process can increase the efficiency of a solar power system by up to 50%. Given those gains, it is an attractive way to enhance an existing solar po
5、wer system. The goal is to build a rig that will accomplish the solar tracking and realize the maximum increase in efficiency. The ultimate goal is that the project will be cost effective that is, the gains received by increased efficiency will more than offset the one time cost of developing the ri
6、g over time. In addition to the functional goals, the Smart House set forth the other following goals for our project: it must not draw external power (self-sustaining), it must be aesthetically pleasing, and it must be weatherproof. The design of our solar tracker consists of three components: the
7、frame, the sensor, and the drive system. Each was carefully reviewed and tested, instituting changes and improvements along the design process. The frame for the tracker is an aluminum prismatic frame supplied by the previous solar tracking group. It utilizes an A-frame design with the rotating axle
8、 in the middle. Attached to the bottom of this square channel axle is the platform which will house the main solar collecting panels. The frame itself is at an angle to direct the panels toward the sun (along with the inclination of the roof). Its rotation tracks the sun from east to west during the
9、 day. The sensor design for the system uses two small solar panels that lie on the same plane as the collecting panels. These sensor panels have mirrors vertically attached between them so that, unless the mirror faces do not receive any sun, they are shading one of the panels, while the other is re
10、ceiving full sunlight. Our sensor relies on this difference in light, which results in a large impedance difference across the panels, to drive the motor in the proper direction until again, the mirrors are not seeing any sunlight, at which point both solar panels on the sensor receive equal sunligh
11、t and no power difference is seen. After evaluation of the previous direct drive system for the tracker, we designed a belt system that would be easier to maintain in the case of a failure. On one end of the frame is a motor that has the drive pulley attached to its output shaft. The motor rotates t
12、he drive belt which then rotates the pulley on the axle. This system is simple and easily disassembled. It is easy to interchange motors as needed for further testing and also allows for optimization of the final gear ratio for response of the tracker. As with any design process there were several s
13、etbacks to our progress. The first and foremost was inclement weather which denied us of valuable testing time. Despite the setbacks, we believe this design and prototype to be a very valuable proof-of-principle. During our testing we have eliminated many of the repetitive problems with the motor an
14、d wiring so that future work on the project will go more smoothly. We also have achieved our goal of tracking the sun in a hands-off demo. We were able to have the tracker rotate under its own power to the angle of the sun and stop without any assistance. This was the main goal set forth to us by th
15、e Smart House so we believe our sensed motion prototype for solar tracking will be the foundation as they move forward in the future development and implementation of this technology to the house. 2. Defining the Problem The project was to complete the “REV 2” design phase of the solar tracker to be
16、 used on the Smart House. While the team was comprised of members from the ME160 senior design course, the customer for this project was to be the Smart House organization. Jeff Schwane, a representative from the Smart House, was our liaison and communicated to our group the direction Smart House le
17、adership wished us to proceed. At our first meeting with Jeff and Tom Rose, the following needs were identified: 1. Track the sun during the day 2. Use no external power source 3. Weather proof 4. Cost effective power gain 5. Must look good 6. Solar panel versatile i.e. can fit different types of pa
18、nels With these needs in hand, we constructed a Quality Function Deployment chart. This chart can be found in Appendix A. The QFD showed the major areas of concern might have been: number of panels/size of panels, internal power requirements, motor torque required. At our first meeting we were also
19、able to set up our goals for the semester. Having a working prototype capable of tracking the sun was to be the main goal for the end of the semester, but we soon found that in order to accomplish this, we would be forced to omit portions of the design criteria in hopes they would be worked out late
20、r. This would result in the optimization of platform space on the roof to be irrelevant, with our goal being to have one platform track. It also led to the assumption that our base would not need to be tested for stability or required to be fastened to the roof. With an idea of where we were to begin, from scratch with the possibility of using the frame from the “REV 1” design, and an idea of where we were to finish, with a moving prototype, we constructed the Gantt
