Maximum power point tracking implementation and solar tracker energization challenges in off-grid battery-less PVRO...

This paper proposes a Maximum Power Point Tracking (MPPT) algorithm for an off-grid, battery-less photovoltaic system that powers a solar desalination plant, including parallel reverse osmosis (RO) modules. The open circuit voltage and surface temperature of the PV array are first measured. Then the MP point voltage (V_MP) is estimated. The PV voltage is estimated before each RO module is activated. So, the RO units are activated sequentially, before reaching the Maximum-Power-Point (MPP). A single-axis solar tracker is integrated to boost power generation capacity. The solar tracker, controlled by a calendar-based relay, does not require a radiation sensor. As the battery has no role in the steady operation of the system, it is replaced with pre-designed capacitors to handle the start-up inrush current of the tracker's motor in the absence of a battery. A two-stage return algorithm is proposed for the solar tracker to return the panels to their initial direction without the need for a battery. So the entire system works without a battery backup. Experimental results from a 1100-watt solar system powering ten RO modules with a total demand of 860 watts demonstrate that the simultaneous implementation of the proposed MPPT and the hourly-operating solar tracker can enhance water desalination capacity by 71%.