solar tracking system using ic l293d and lm339 block diagram pdf

Generally, solar panels are stationary and do not follow the movement of the sun [1].Here is a solar tracker system That
tracks the sun’s movement across the sky and tries to maintain the solar panel perpendicular to the sun’s ray, Ensuring
that the maximum amount of sunlight is incident on the panel throughout the day till evening [2].
Photovoltaic’s is the field of technology and research related to the application of solar cells as solar energy [3]. Solar
cells have many applications. Individual cells are used for powering small devices such as electronic calculators.
Photovoltaic arrays generate a form of renewable electricity, particularly useful in situations where electrical power from
the grid is unavailable such as in remote area power systems, Earth-orbiting satellites and space probes, remote
radiotelephones and water pumping applications. Photovoltaic electricity is also increasingly deployed in grid-tied
electrical systems.
Solar Energy has been the power supply of choice for Industrial applications, where power is required at remote
locations. Most systems in individual uses require a few kilowatts of power. The examples are powering repeater stations
for microwave, TV and radio, telemetry and radio telephones. Solar energy is also frequently used on transportation
signaling e.g. light houses and increasingly in road traffic warning signals. Solar's great benefit here is that it is highly
reliable and requires little maintenance [4].
While the output of solar cells depends on the intensity of sunlight and the angle of incidence, it means to get maximum
efficiency; the solar panels must remain in front of sun during the whole day. But due to rotation of earth those panels
can’t maintain their position always in front of sun. This problem results in decrease of their efficiency. Thus to get a
constant output, an automated system is required which should be capable to constantly rotate the solar panel. The Solar
Tracking System is made as a prototype to solve the problem, mentioned above. It is completely automatic and keeps the
panel in front of sun where we get maximum output.
II. SYSTEM DEVELOPMENT
 East: Initiate the sensor
 During the day tracker function as the usual
 West: tracker function as usual
 At Evening and night tracker doesn’t react.
Fig. 1. Block diagram of solar tracking system
International Journal of Enhanced Research in Science Technology & Engineering, ISSN: 2319-7463
Vol. 2 Issue 8, August-2013, pp: (68-71), Available online at: erpublications.com
Page | 69
A solar cell, sometimes called a photovoltaic cell, is a device that converts light energy into electrical energy. A single
solar cell creates a very small amount of energy (about .6 volts DC) so they are usually grouped together in an integrated
electrical panel called a solar panel. Sunlight is a somewhat diffuse form of energy and only a portion of the light
captured by a solar cell is converted into electricity.
Sunlight is made up of packets of energy called photons. When the photons strike the semi-conductor layer (usually
silicon) of a solar cell a portion of the photons are absorbed by the material rather than bouncing off of it or going
through the material. When a photon is absorbed the energy of that photon is transferred to an electron in an atom of the
cell causing the electron to escape from its normal position. This creates, in essence, a hole in the atom. This hole will
attract another electron from a nearby atom now creating yet another whole, which in turn is again filled by an electron
from another atom.
One of the problems with solar power is that the output of the solar panel is variable. These solar systems are designed to
extract the maximum amount of power available from the solar panels and deposit it in the battery. These solar charge
controllers also protect your panels from discharging through the batteries after the sun goes down.
Talking of the design of solar panel battery chargers, solar panel battery charger manufacturers use thin film second
generation technology to create these devices. This is to take advantage of the flexible nature of this kind of solar cell
technology. Solar battery chargers used on boats and on water can be found in waterproof prototypes. Solar panels used
to capture and convert energy from the sun into electrons are offered in various volts gradations; a solar panel battery
charger is available from 2 watt to 30 watt range.
Table 1: Voltage and Current Specification
Discrete Components Ratings
Lead Acid Battery Voltage 12 VDC
Maximum Solar PV panel open circuit voltage 18 VDC
Continuous charge/load current 800mA
Maximum solar charge current (5 min) 850mA
Voltage across terminals (PV to Battery) 0.6 V
Voltage across terminals (Battery to Load) 0.3V
An LDR (Light dependent resistor), as its name suggests, offers resistance in response to the ambient light. The
resistance decreases as the intensity of incident light increases, and vice versa. In the absence of light, LDR exhibits a
resistance of the order of mega-ohms which decreases to few hundred ohms in the presence of light. It can act as a
sensor, since a varying voltage drop can be obtained in accordance with the varying light. It is made up of cadmium
sulphide (CdS).
An LDR has a zigzag cadmium sulphide track. It is a bilateral device, i.e., conducts in both directions in same fashion.

A solar tracker is a device that orients a payload toward the Sun. Payloads are usually solar panels, parabolic troughs, fresnel reflectors, mirrors or lenses.

For flat-panel photovoltaic systems, trackers are used to minimize the angle of incidence between the incoming sunlight and a photovoltaic panel. This increases the amount of energy produced from a fixed amount of installed power generating capacity. In standard photovoltaic applications, it was predicted in 2008-2009 that trackers could be used in at least 85% of commercial installations greater than one megawatt from 2009 to 2012. However, as of April 2014, there is not any data to support these predictions.

In concentrator photovoltaics (CPV) and concentrated solar power (CSP) applications, trackers are used to enable the optical components in the CPV and CSP systems. The optics in concentrated solar applications accept the direct component of sunlight light and therefore must be oriented appropriately to collect energy. Tracking systems are found in all concentrator applications because such systems do not produce energy unless pointed at the Sun.