SLVAFC9 August   2022 TPS61094

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction of Solar Cell and MPPT
    1. 1.1 Traditional MPPT Solution
  4. 2Typical System with Solar cell
    1. 2.1 General Introduction
    2. 2.2 Specific End Equipment
      1. 2.2.1 System Requirements
  5. 3TPS61094 Solution
    1. 3.1 Supercap and Battery Design
    2. 3.2 Solar Panel Design
    3. 3.3 TPS61094 Description and Operation
    4. 3.4 System Solution
  6. 4Test Report Based on TPS61094 Solution
    1. 4.1 Test Waveform
  7. 5References

1 Introduction of Solar Cell and MPPT

A solar cell is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon. The common single junction silicon solar cell can produce a maximum open-circuit voltage of approximately 0.5 V to 0.6 V. Individual solar cell devices are often the electrical building blocks of photovoltaic modules. The most commonly known solar cell is configured as a large-area p-n junction made from silicon.

Open circuit voltage and short circuit current are the most important parameters of solar panels. In general, its operating voltage and current vary with the load resistance (Energy Harvesting From Single Cell Solar Panel for Li-Ion Battery Reference Design). Figure 1-1 shows the operating current and voltage corresponding to different loads, which is the VI/VQ curve of the solar cell.

Figure 1-1 VI/VQ Curve of Solar Cell

Under different lighting conditions, the same solar panel has different maximum output power according to different loads. It’s important to make the solar panel work at the maximum power point through adjustment. Maximum power point tracking is a technique used with variable power sources to maximize energy extraction as conditions vary. It maximizes energy extraction when conditions change. The central problem addressed by MPPT is that the efficiency of power transfer from the solar cell depends on the amount of available sunlight, solar panel temperature and the load’ s electrical characteristics. As these conditions vary, the load characteristic that gives the highest power transfer changes. The system is optimized when the load characteristic changes to keep power transfer at highest efficiency. This optimal load characteristic is called the maximum power point (MPP). MPPT is the process of adjusting the load characteristic as the conditions change. Circuits can be designed to present optimal loads to the photovoltaic cells and then convert the voltage, current, or frequency to suit other devices or systems.