Abstract:
Over the years, perovskite solar cells have continued to improve, and now the Internet
of Things (IoT) devices can be powered by these emerging photovoltaic (PV) cells for indoor
applications. This work develops a PV-powered charger that constantly supplies an IoT device
and has a stand-by battery. The battery serves to assist the PV during Fractional Open-Circuit
Voltage (FOCV) Maximum Power Point Tracking (MPPT) probing, low PV generation, and
night times. Battery charging and discharging simulations are included as well. Simulations
were conducted using LTspice software. The perovskite solar cell simulation model is designed
using on-site behavioral conditions. The battery model is designed according to the common
Li-ion battery behavior. Voltage matching between the PV and battery is performed using a
boost converter. The charger uses a FOCV MPPT approach. Sample and Hold (S&H) circuit
technique is included to enhance MPPT performance. FOCV applies a scaling constant to
calculate maximum power point voltage using open-circuit voltage; however, the scaling
constant is different for each irradiance level. Therefore, a light-dependent resistor (LDR) is
added to the voltage divider part of the FOCV for maximum power point adjustments during
light level variations. Case studies of PV-powered charger were conducted for irradiance levels
of 0.03 and 1 sun, and different battery charge states. According to simulations of different
scenarios demonstrated in case studies, the charger circuit operates as designed initially.