A modular strategy for isolated photovoltaic systems based on microcontroller

Many different types of commercial regulators can be found in the market. These devices can be basically divided into two categories according to their operation mode: those which modulate the input voltage using PWM (pulse-width modulation) in order to generate the output voltage required to charge the batteries; and those which make the PV (photovoltaic) array operate in their MPP (maximum power point), which can be tracked in several different ways. The former are normally used for low-power applications, whereas the latter can provide an increase of power up to 25% as compared to their PWM counterpart. This paper presents a regulator which can operate in the maximum power point of PV arrays by means of a microcontroller. A simple, highly-accurate algorithm suitable to be implemented in a low-cost microcontroller has been developed in order to make PV arrays track and operate in their maximum power point. The control strategy proposed allows parallel connection of different regulators, thus making it possible to keep and integrate previous equipment.