Design And Construction Of A Microcontroller Based Solar Charge Controller

ABSTRACT

Solar charge controller limits the rate at which electric current is added to or drawn from solar panel to electric batteries. It prevents overcharging and may protect against overvoltage, which can reduce battery performance or lifespan, and may pose a safety risk. It may also prevent completely draining (“deep discharging”) a battery, or perform controlled discharges, depending on the battery technology, to protect battery life. The terms “charge controller” or “charge regulator” may refer to either a stand-alone device, or to control circuitry integrated within a battery pack, solar battery-powered device, or battery charger.

CHAPTER ONE

1.0                                                        INTRODUCTION

Energy plays vital role for development in all sectors. With depletion of fossil fuels used for power generation and increase in demand for power, the gap between supply and demand is becoming more. Renewable energy sources can only provide solution to face this energy crisis. Out of renewable energy options, solar energy is the most potential source for all tropical countries. Sun radiates 180 billion MW of energy over Earth Just one hour of this energy could meet power needs of entire planet for a year. India receives 5000 Trillion KWhrs of energy from SUN per annum. This energy is clean, pollution free and inexhaustible and is available free and in abundance. Basically the components involved in solar system are PV panel, DC-DC Converter, Battery, Inverter.

The PV panel produces electrical voltage/current from solar energy. This solar panel can produce more than the rated voltage to the battery which can be dangerous to the battery due to the high radiation of the sun. In order to tackle the present energy crisis it is necessary to develop an efficient manner in which power has to be extracted from the incoming solar radiation. The use of the newest power control mechanisms called solar charge controller was invented.

Solar Charge controller is basically a voltage and/or current regulator to keep batteries from overcharging.

Solar Charge Controller is fully configurable and developed to meet the highest industry standards to ensure maximal efficiency in retrieving energy from any PV system. When connected to solar panels and batteries, the solar charge controller automatically charges the batteries in an optimal way with all the available solar power. Solar charger controller’s sophisticated three stage charge control system can be configured to optimize charge parameters to precise battery requirements. The unit is fully protected against voltage transients, over temperature, over current, reverse battery and reverse PV connections. An automatic current limit feature allows use of the full capability without worrying about overload from excessive current, voltage or amp-hour based load control.

1.1                                             OBJECTIVE OF THE PROJECT

The objective of this work is to design a device that will maintain the required voltage magnitude coming from solar panel necessary for the load or control the battery voltage supplied from solar panel. This device is built around a AT89C2051 microcontroller, Microcontroller AT89C2051 is the heart of the circuit. It is a low-voltage, high-performance, 8-bit microcontroller that features 2 kB of Flash, 128 bytes of RAM, 15 input/ output (I/O) lines, two 16-bit timers/ counters, a five-vector two-level interrupt architecture, a full-duplex serial port, a precision analogue comparator, on-chip oscillator and clock circuitry.

1.2                                                 SCOPE OF THE PROJECT

The main scope of project is, the photovoltaic cells are converting the sunlight in to electricity a charge controller is used. PV cells are bundled together in modules or panels to produce higher voltages and increased power. As the sunlight varies in intensity the electricity so generated usually charges through the charge a set of batteries for storing the energy. Controller in this project is used: To generate the variable PWM for DC-DC CONVERTER, to control the battery voltage and Controlling the load variation.

1.3                                         SIGNIFICANCE OF THE PROJECT

Solar Charge controller is basically a voltage and/or current regulator to keep batteries from overcharging. It regulates the voltage and current coming from the solar panels going to the battery. Most “12 volt” panels put out about 16 to 20 volts, so if there is no regulation the batteries will be damaged from overcharging. Most batteries need around 14 to 14.5 volts to get fully charged.

Solar Charge controller may also monitor battery temperature to prevent overheating. Some charge controller systems also display data, transmit data to remote displays, and data logging to track electric flow over time.

1.4                                              PURPOSE OF THE PROJECT

Use of batteries with solar panels is usually not good. So to avoid failure of batteries before time solar charge controller is used. For example you have a 12 volt battery and you want to charge it with 12 volt solar panel. 12 volt solar panel outputs 17-20 volt. So these 17-20 volt may damage battery due to overcharging, because batteries maximum charging voltage is usually between 13.5-14 volt. To avoid this issue we need to develop a regulator which can control flow of charge from solar panel towards battery. Solar charge controller is used for this purpose.

1.5                                          APPLICATION OF THE PROJECT

Solar Charge controller circuits are used for rechargeable electronic devices such as cell phones, laptop computers, portable audio players, and uninterruptible power supplies, as well as for larger battery systems found in electric vehicles and orbiting space satellites.

1.6                          PROJECT WORK ORGANISATION

The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this work is on the introduction to the study. In this chapter, the background, significance, objective, purpose, and application of the study were discussed.

Chapter two is on literature review of this study. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, recommendation and references.