A reliable and efficient circuitry for photovoltaic energy harvestin for powering marine instrumentations

This paper presents and demonstrates a simple and reliable electronic circuitry for photovoltaic energy harvesting which best suited for powering marine instrumentations. The main functions of the designed circuitry are: i) tracking the maximum power point of the photovoltaic cells which are subject to continuous movements due to sea waves, ii) power conversion and management of energy storages with a high efficiency; and iii) achieving a high level of reliability for operation of circuit in a harsh marine environment. The proposed circuitry is designed based on an analog controller which implements a sensor-less algorithm for maximum power point tracking. The power converter unit includes a simple buck converter with minimum electronic components. Compared with DSP-based digital controllers, the simplicity of the proposed analog controller highly improves reliability of the power conversion unit. The total power consumption of the electronic circuit is in the range of a few milliwatts. This enhances the overall efficiency of power conversion especially in low power (a few watt) applications such as powering of marine and metrological sensors. The circuitry also includes a control unit for battery charging to protect batteries against overcharging. The performance of the designed circuitry is experimentally demonstrated using a test setup for power management unit of an ocean-graphical buoy.