A Really low voltage solar MPPT

Abstract

Energy harvesting or scavenging describes the process of extracting useful electrical energy from other ambient energy sources. Three main sources of ambient energy include vibrational, thermal and solar energy. Through the use of special materials that have the ability to convert one form of energy into the other energy harvesting can be accomplished. Even though most of the energy coupling materials currently available have been around for several decades, their use for the specific purpose of energy harvesting has not been thoroughly examined until recently, when the power requirements of many electronic devices has reduced drastically. Of the three main sources of energy, the solar cell has been the most effective is achieving this translation of energy. Solar cells have been widely used in low power electronics such as calculators where several of these are placed in series to achieve a voltage high enough to operate the device. Further serialization and scaling of solar cells allows solar arrays in terrestrial applications to reach enough voltage to generate three phase voltages for energy distribution in the main power grid. The scope of this project deals with the output characteristics of one solar cell as the energy source. The voltages range from 600mV to 3V depending on the solar radiation levels and the technology of the cell itself. The desired output voltage is 12V. Several circuit topologies to achieve this high voltage gain are presented and discussed. Algorithms to track the maximum power output of the solar cell are presented. As a result a practical circuit design is proposed to allow for further future research on the problem to be solved.