| | Category | EN | P12 | Helius: A Solar-Tracking Mechanism for Efficiency Max. Of |
| | Photovoltaic Modules |
| | Abstract | Photovoltaic modules are generally plagued with a common dilemma, |
| | lack of efficiency due to their immobility. One solution to this dilemma can |
| | be found in one of the vast wonders of our environment, the sunflower. |
| | This American native plant possesses a characteristic that could possibly |
| | increase the efficiency of photovoltaic modules, when properly applied. |
| | The mystery behind this solution is the process known as heliotropism, the |
| | diurnal motion of plant parts (flowers or leaves) in the response to the |
| | direction of the sun. |
| | To apply this concept to the modern field of technology, this project will |
| | attempt to mechanically mimic the heliotrophic characteristics of the |
| | sunflower at its bud stage. Although the original design of the project was |
| | in the form of a mechanical sunflower, the main focus will be centralized |
| | around the control, or the head, of the sunflower. Four photovoltaic panels |
| | will be attached to each other to accurately track the location of the sun. |
| | The motion of the device will be powered by the Arduino Duemilanove |
| | microcontroller, which uses the Atmel ATmega328 and must be |
| | programmed with C++ language, and the OWI-535 Robotic Arm Edge for |
| | arrays, which was assembled along with the rest of the project. |
| | The methodology behind this project is fairly simple. Apart from the C++ |
| | coding, cross-partitions are implemented to ensure that the cell panel is |
| | always perpendicular to the direction of maximum illumination. If the panel |
| | is off-axis, one cell in a pair will be in partial shadow, so its output voltage |
| | will fall. The circuitry of the Arduino measures the voltage difference |
| | between the cells and turns on the appropriate drive motor to move the |
| | panel in the direction that will make it perpendicular again, when the |
| | shadow is eliminated. |
| | Two pairs of cells, two orthogonal drive motors, about 90 degrees of |
| | movement in each axis, produces more than enough solid angle of |
| | movement to track the light. The smart bit is making the measurements |
| | differential rather than absolute. If we just measured the illumination and |
| | used that as a guide, then the tracker would be fooled every time the Sun |
| | went behind a cloud. This way, if the panel is at right angles to the Sun, |
| | then the difference between the cells will be zero, no matter how bright |
| | the Sun is. Also, the tracker will eventually be configured to power itself, |
| | as well as supply an ample amount of energy for storage. |
| | Bibliography | http://www.national.com/an/AN/AN-20.pdf |