DESIGN OF MONO-AXIS SOLAR TRACKING SYSTEM USING MICROCONTROLLER BASED STEPPER MOTOR KAMAL J K KOUSHIK VENKATRAMAN N PREM M PRASANTH K Guidance: Mrs.Kavitha (AP)

INTRODUCTION With the increasing threat of global warming and the depletion of fossil fuel reserves, many are adopting sustainable energy solutions. Other than the hydro power, the wind etc., photovoltaic (solar) energies have higher potential to meet our energy demands. The major advantage of a solar system is the enhanced reliability of the system.

OBJECTIVES To program the microcontroller for controlling the stepper motor. To connect the stepper motor with the panel thereby enabling panel rotation. To fix the mirrors on the panel for effective concentration of the radiation over the panel. To store the generated energy in the battery, invert it and finally transfer it to the load.

DESCRIPTION The main objective of our project is to track the solar radiation and increase the intensity of the solar radiation by employing reflecting mirrors over the panel and thereby improve the efficiency of power generation. In this, a solar panel is energized and the power thus generated is inverted and then fed to the load. The microcontroller controls the rotation of the motor depending upon the output of the solar panel.

BLOCK DIAGRAM

Working The solar panel receives sunlight along with the LDR The panel is mounted and a stepper motor controlled by a microcontroller is connected to it. The microcontroller receives the intensity of the sunlight in form of analog signal from LDR When the intensity of the sunlight becomes less when the sun changes its position, the panel rotates with the help of stepper motor facing the sunlight based on the control signal received from the controller. Then the battery is charged by the solar panel followed by inverted supply to the load

COMPONENTS Solar panel Stepper motor Micro controller Battery Inverter Load

Solar panel Solar panels use light energy from the sun to generate electricity through the photovoltaic effect. Majority of modules use wafer-based silicon cells or thin-film cells based on cadmium telluride or silicon. The structural member of a module can either be the top layer or the back layer. The panel used is a 3.5 W and a 12 V panel

Stepper motor A stepper or stepping motor converts electronic pulses into proportionate mechanical movement. Each revolution of the stepper motor's shaft is made up of a series of discrete individual steps. A bipolar motor is used which has 4 windings. Steps- 1.8’ per step Current -.45 A Resistance – 29 ohms

Microcontroller The PIC16F873A and PIC16F874A have one-half of the total on-chip memory of the PIC16F876A and PIC16F877A. The 28-pin device has three I/O ports, while the 40/44-pin devices have five. The 28-pin device has fourteen interrupts, while the 40/44-pin devices have fifteen. The 28-pin devices have five A/D input channels, while the 40/44-pin devices have eight.

Motor driver unit

EXISTING METHOD : Most of the systems in operation use a separate DC/DC boost converter connected in parallel to the rectifier stage, to perform the MPPT control for each of the renewable energy power sources. A simpler multi input structure has been suggested that combines the sources from the sun and the reflected radiation from the mirrors that are focused onto the panel.

PROPOSED METHOD: In this method, two mirrors are placed over the solar panel which effectively directs the solar radiation towards the panel. The microcontroller controls the movement of the panel depending upon the output voltage from the panel.

Inverter unit

Power supply unit Power supply is a reference to a source of electrical power. A device or system that supplies electrical or other types of energy to an output load or group of loads is called a power supply unit or PSU. The term is most commonly applied to electrical energy supplies, less often to mechanical ones, and rarely to others.

POWER CIRCUIT FOR MICROCONTROLLER

The operation of power supply circuits built using filters, rectifiers, and then voltage regulators. Starting with an AC voltage, a steady DC voltage is obtained by rectifying the AC voltage, then filtering it to a DC level, and finally, regulating to obtain the desired fixed DC voltage. The regulation is usually obtained from an IC voltage regulator Unit, which takes a DC voltage and provides a somewhat lower DC voltage, which remains the same even if the input DC voltage varies, or the output Load connected to the DC voltage changes.

MICROCONTROLLER

DRIVER CIRCUIT

There are many situations where signals and data need to be transferred from one subsystem to another within a piece of electronics equipment, without making a direct ohmic electrical connection. Often this is because the source and destination are at very different voltage levels, like a microprocessor, which is operating from 5V DC but being used to control a triac that is switching 240V AC. In such situations the link between the two must be an isolated one, to protect the microprocessor from over voltage damage.

OPTOCOUPLER Optocoupler uses a beam of light to transmit the signals or data across an electrical barrier and achieve excellent isolation. Optocoupler typically comes in a small 6-pin or 8-pin IC package, but are essentially a combination of two distinct devices: an optical transmitter and an optical receiver such as a phototransistor or light-triggered diac. The two are separated by a transparent barrier which blocks any electrical current flow between the two, but does allow the passage of light. This usually allows optocouplers to withstand voltages of anywhere between 500V and 7500V between input and output. Optocouplers are essentially, digital or switching devices, so they’re best for transferring either on-off control signals or digital data.

OPTOCOUPLERS

WORKING AC supply is given to Darlington pair of transistors on the driver circuit as well as to the bridge rect. on the controller unit. The dc o/p is given to the voltage regulator from which 5V is supplied to the microcontroller. The pulse duration of the pulses generated by the crystal oscillator is set by the microcontroller. The generated pulses are amplified and give to the driver unit. From here, the pulses are given to switches which conduct alternatively and produces AC output

COST ESTIMATION Solar panel-Rs.800 Driver Circuit-Rs.300 Stepper Motor-Rs Microcontroller-Rs.250 Arduino-R.1500 Inverter-Rs Battery-Rs

ADVANTAGES: The intensity of the solar radiation is increased. Uninterrupted power output. Minimum loss due to reduction of components.