Battery charge controller characteristics in photovoltaic systems

Abstract

Stand-alone photovoltaic (PV) systems are becoming increasingly viable and cost-effective for remote and/or offutility grid power requirements. Thousands of PV systems are being installed annually in the United States and abroad with typical applications including lighting, telecommunications, and other battery charging requirements. In general, a standalone PV system consists of a PV array, which converts sunlight to direct-current electricity, energy storage in the form of secondary batteries, loads or appliances, and a control system, which regulates battery charging and operation of the load. While PV module development over the past decade has resulted in a highly reliable product, the performance of battery and charge controller sub-systems have indicated a need for improvement. These deficient areas include proper specification of charging requirements and control set points for the battery type and environment. A better understanding of how batteries (less than 220 Ah) operate in PV systems is essential for the success of this market. Specifications applicable to the low charge/discharge rates typical in PV systems need to be published in the battery technical literature. This paper presents typical strategies for battery charge regulation and load control used in stand alone PV systems. Several charge algorithms (methods of controlling current to the battery) are presented, along with terminology used by the PV industry for battery charge controllers. Information gained from an extensive evaluation of commercially available charge controllers is discussed along with data collected from tests on PV systems in the field. Finally, an overview of battery performance characteristics needed for the successful design and long-term operation of PV systems is presented with the

On the Design of an Intelligent Battery Charge Controller for PV Panels

“…Charge controllers are designed to improve charge efficiency and safety. The primary function of a charge controller is to protect the battery from overcharge and over discharge in a stand-alone PV system [2]. There are a lot of studies about the charge controller in the literature.…”

“…There are a lot of studies about the charge controller in the literature. Harrington and Dunlop (1992) analyzed the typical strategies for battery charge regulation in stand-alone PV systems and conclude that the battery information is very important in designing PV systems [2]. Ullah et al (1996) focused on the design of a super-fast battery charger based on National's proprietary neural network based neural fuzzy technology.…”

Improvements to a Bi-directional Flyback DC-DC Converter for Battery System of the DC House Project

“…A shunt controller regulates the charging of a battery by interrupting the PV current by short-circuiting the array. A blocking diode is required in series between the battery and the switching element to keep the battery from being shorted [15]. A series controller regulates the charging of a battery by using series-interrupting where battery charging is terminated when voltage reaches a VR set point.…”

“…In a stand-alone photovoltaic (PV) system, charge controllers are commonly used to provide this type of regulation. Their primary function is to protect the battery from overcharge and over-discharge [15]. Basic charge controllers operate using set points.…”

“…At this point a controller will either discontinue battery charging or begin to regulate the amount of current delivered to the battery. The LVD is the voltage at which the load is disconnected from the battery to prevent over-discharge [15].…”