1 Introduction

The Maximum Power Point Tracking (MPPT) is essential in solar-powered systems to make sure that photovoltaic (PV) panels deliver the highest possible power output, which varies depending on sunlight intensity, temperature, and dynamic environmental conditions such as cloud cover or shading. The power generated by a solar panel is the product of voltage and current (P = V × I), and this relationship forms a curve where the peak corresponds to the maximum power point (MPP).Without MPPT, the system can operate at less than excellent voltage and current levels, leading to significant decrease in available energy.

The BQ2575x family of buck-boost battery chargers includes an internal MPPT feature based on full panel sweeps, where the input voltage is stepped down across a wide range while monitoring charge current. This method identifies the voltage that yields the highest charge current (and by extension, power).

While the full panel sweep can accurately locate the maximum power point and is an excellent choice for most solar charging applications, the full panel sweep requires sweeping the panel every time the MPP needs updating. As shown in Figure 1-2, the operating voltage often moves away from MPP during the sweep, causing the charge current to temporarily decrease. This lowers the average power harvested and reduces efficiency. Additionally, with a minimum timer of three minutes, environmental changes within that window can cause the system to deviate from the true MPP until the next sweep occurs, further impacting efficiency and is not an excellent choice for rapidly changing conditions.

For applications that require faster or more continuous tracking, such as mobile or shaded solar environment, MPPT performance can be improved by implementing the Perturb and Observe (P&O) algorithm externally using a host microcontroller.