Flexible photovoltaic micro-power system enabled with a customized MPPT

With the requirement for self-powering functionality in wearable electronics, a small power range flexible photovoltaic micro-power system is evidently needed. Furthermore, non-flexibility, large volume/weight, power consumption constraints, and cost considerations make it impractical to directly use the large power range complex maximum power point tracking (MPPT) algorithm and hardware in wearable electronics. This work aims to design a fully flexible photovoltaic micro-power system for reliable energy supply within the low power range for wearable electronics. In this study, a customized fractional open circuit voltage (FOCV) algorithm and a performance-matching DC-DC converter are designed, and then integrated with a flexible perovskite solar module to develop a fully flexible photovoltaic micro-power system. Indoor and outdoor experiments are conducted to evaluate its performance. The designed MPPT system achieves a high tracking accuracy of 99.25% at a power of 0.539 W with a fast tracking time of 0.20 s, which is an effective improvement over the traditional algorithms. These values are 97.8% and 0.21 s under shaded lighting conditions. The MPPT system is lightweight (4.6 g) with a size of <3 × 3 cm2. Tracking experiments with flexible solar modules after bending also demonstrate the flexibility of the system, which also shows the high utilization and fast response capability for small power range photovoltaic outputs. The fully flexible photovoltaic micro-power system demonstrates great potential for future wearable electronics and expands the way to efficiently harvest solar energy in highly adaptive and dynamic applications.