Automatic solar tracker - A new trend to minimise the use of non renewable sources of energy.

1. Concept : We all are familiar with the Solar Panel :
Newton's corpuscular theory of light,
that light is made up of small particles
called “corpuscles” which travel in
straight line with a finite velocity and
energy.
SOLAR ENERGY :
 It is the major Eco-friendly & Pollution
less method of producing the
electricity today.
 Acc. to- U.S. solar research center:
“ If we convert the Total Solar
energy reaches to earth in one time It is a large component made up of the no of
into ELECTRICITY, then it will be more photovoltaic cells connected internally with
enough than whole power used by all each other. Used to grab the sunlight and to
the nations per year. “ convert it into the ELECTRICITY.

2. What is a solar tracker ?
A Solar tracker is a device used
for orienting a solar photovoltaic panel
or lens towards the sun by using the
solar or light sensors connected with the
machine ( ex: stepper motor, servo
motor, gas filled piston ).
Hence, The sun tracking systems can
collect more energy than what a fixed
panel system collects.

3. NEED OF SOLAR TRACKER
Commercial purpose :
• Increase Solar Panel Output
• max.efficency of the panel
• Maximize Power per unit Area
• Able to grab the energy through out
the day .

4. Types of Solar Trackers
1. Single Axis Solar Tracker
The sun's position in the sky varies both Single axis solar trackers can either have a
with the seasons (elevation) and time horizontal or a vertical axle. The
of day as the sun moves across the horizontal type is used in tropical regions where
sky. the sun gets very high at noon, but
the days are short. The vertical type is used in
• Hence there are also two types of
high latitudes (such as in UK) where
SOLAR TRACKER :
the sun does not get very high, but summer days
can be very long.
 Single Axis Solar Tracker.
 Dual Axis Solar Tracker.

5. 2. Dual Axis Trackers Dual axis Solar tracker fig :
Double axis solar trackers have both a
horizontal and a vertical axle and so can
track the Sun's apparent motion exactly
anywhere in the world.
This type of system is used to
control astronomical telescopes, and so
there is plenty of software available to
automatically predict and track the
motion of the sun across the sky.
Dual axis trackers track the
sun both East to West and North to
South for added power output (approx
40% gain) and convenience.

6. Overview of Present Tracker Drive Types
Solar tracker Drives, can be divided into
three main types depending on the
type of drive and sensing or
positioning system that they Solar Tracker
Drives
incorporate.
• 1. Passive trackers : use the sun’s
radiation to heat gases that move the
1.Passive
tracker across the sky. 2.Active 3. Open Loop
Trackers
Trackers Trackers
• 2. Active trackers : use electric or
hydraulic drives and some type of
gearing or actuator to move the
tracker.
• 3. Open loop trackers : use no sensing
but instead determine the position of
the sun through pre recorded data for
a particular site.

7. 1. Passive ( Gas ) Trackers
Passive trackers use a compressed when the sun appears and disappears
gas fluid in two canisters each place in west & behind clouds, causing the gas in the liquid in
east of the tracker. The mechanism is in such a cylinders to expand and contract resulting in erratic
way that if one side cylinder is heated other movement of the device, often causes DAMAGE.
side piston rises causing the panel to tilt over
the sunny side.
This affects the balance of the
tracker and caused it to tilt. This system is very
reliable and needs little maintenance.
Advantages :
They are cheaper & effectively increase the
efficiency of the solar panel.
Disadvantages:
gas tracker will very rarely point the solar panels
directly to the sun, due to the temperature
varies from day to day and Overcast days are
also a problem can damage the panel.

8. 2. Active Trackers
Active trackers : measure the light
intensity from the sun by using “ light
sensors “ to determine where the solar
modules should be pointing.
Light sensors are positioned on the
tracker at various locations in specially
shaped holders.
If the sun is not facing the tracker
directly there will be a difference in light
intensity on one light sensor compared
to another and this causes to determine
in which direction the tracker has to tilt
with the help of the stepper or dc motor
in order to be facing the sun.
DRAWBACKS: On overcast days it will be
not so working properly due to clouds.

9. 3. Open Loop Solar Trackers
DEFINATION : Open loop trackers determine the
position of the sun using computer controlled
algorithms or simple timing systems.
1. Timed Trackers-
A timer is used to move the tracker
across the sky. Incremental movement throughout
the day keeps the solar panel pointing the sun.
Advantages: can be utilize as one or two axes
panels.
Disadvantage: Does not take into account the
seasonal variation in sun position.
2. Altitude / Azimuth Trackers-
It uses the astronomical data or sun
position algorithms to determine the position of
sun for any given time and location by using micro
controller.
Once the position has been calculated, the
modules are moved using servo motors and there
position measured by encoders built into the
tracker frame.

10. Some Interesting Power Facts
Efficiency increased by using solar trackers for one PV-cell.
INDIAN POWER
GENERATION
8% Thermal
3%
Hydro
25%
Nuclear
64%
Renewable
souces