Design and Fabrication of an Intelligent Controller for a Commercial Stand-Alone Photovoltaic System

In a stand-alone photovoltaic (PV) system, the battery gives the biggest recovering cost component of the system. Most attention must be given to this type of energy storage. An intelligent charge controller is one good way of prolonging the battery life. The charge controller system is a very well established technology that covers a spectrum of low-end to high-end technologies. It involves a combination of the art of electronic concepts, feedback and feedforward control system and power electronics devices. Besides controlling the recharging of the integral battery, the functions of the controller may also include switching the available option loads, monitoring the performance of the system and giving warnings when the system is not properly functioning. The objective of this paper is to present the design and fabrication of a charge controller that is compatible with most parts of the PV system. It is an intelligent low-cost battery operated controller intended for commercial uses. A simple proportional-integral controller will be discussed to first determine the optimum operating point, followed by the comparison between an ON-OFF controller, a proportional-derivative controller and a fuzzy logic controller. This paper also discusses the principles, circuitry design and components selection for the controller fabrication.