N.Arunraja

S.Gowtham Aswin

The modern demands for electricity is pushing the energy sector to its limits. With the risk of exhausting the fossil fuels becoming a reality, it is necessary to focus more on renewable sources such as solar energy.

To make use of this bounty-full source, one of the prominent methods is to use solar panels, to get electrical energy out of solar energy.

But to achieve maximum potential power extraction, the solar panel must be held normal to suns radiation at all times.

OBJECTIVE DESCRIPTION

This project aims at

maximizing the power

output of a solar panel by

orienting the solar panel

according to the position of

sun throughout day.

The system uses a simple

traveling nut actuator to

impart the required motion

to the solar panel. A

microcontroller is used to

operate the stepper motor to

effectively control the

panel's position with respect

to the sun.

Azimuth : It is the

angle by which the sun

is displaced from the

exact centre of the sky.

Zenith : It is the actual

inclination of the sun to

the apparent horizontal

plane.

AZIMUTH ZENITH

The azimuth of the sun to a location varies from one place to another.

It is in direct proportion to the latitude of the considered location.

Generally, for southern India it is about 15 degrees in average.

The corresponding arrangement can be adjusted by changing the lengths of the

The zenith of the sun varies

approximately from 0 to 180

degrees throughout the day.

To achieve normal orientation

of the panel to the suns rays, a

simple timed motor controlled

using a microcontroller is

used.

The basic idea is to use a simple mechanical system which aligns the solar panel using a linear actuator. The solar panel is mounted on a rotating shaft.

This shaft is fixed to the frame through bearings. One end of the shaft is fixed with an extended lever arm which is connected to a linear actuator.

Any linear motion to the arm rotates the solar panel by an angle corresponding to the linear displacement.

The linear actuation is provided by a stepper motor which has been coupled to the lead screw and nut arrangement

The major components in the

setup include

1. Frame and bearings

2. Shaft

3. Panel holder

4. Lever arm

5. Lead screw and Nut

arrangement

6. Stepper motor

7. Microcontroller setup

SOLAR PANEL :

A 18 cell 9V 5W solar panel was acquired from Free Spirits

Green Labs. It is a polycrystalline solar panel, which has a life of

more than 25 years.

MICROCONTROLLER :

An Arduino platform board with Atmega-8 microcontroller was

used for the project.

STEPPER MOTOR :

After initial calculations a simple and mass produced 5V stepper

motor (28BYJ-48) is selected. It is 12 steps per revolution,

geared motor with a gear ratio of 64:1.

TRAVELLING NUT ACTUATOR :

It is a simple leadscrew and nut arrangement where theleadscrew is fixed. The nut moves linearly with respect to the rotarymotion of the leadscrew.

SHAFT AND PANEL HOLDER :

The solar panel is kept in a panel holder of suitable design, thispanel holder is fixed to a rotating shaft which in turn is fixed to theslider arm.

SLIDER ARM :

As the nut moves corresponding to the leadscrew movement, itslides in a slider arm connected to the shaft which converts thelinear motion into corresponding rotary motion.

DRIVE SETUP :

The stepper motor is independently fixed to the panel with the help

of two screws. The drive from the plank is transmitted through a

pair of gears to lead screw. A M6 thread rod of pitch 1mm is used

as the lead screw in this arrangement.

The thread rod is cut to a required length and is put in the steel

plank through a drilled hole. The lead screw is held in place using a

lock nut, thus allowing free rotation. The gear ratio given to the

motor and the shaft is 2.5.

The nut arrangement is provided by the connection joint, which is

drilled with a 6mm bit and tapped with a M6 tap. This is threaded

along the lead screw providing the nut arrangement of the lead

screw.

A. Lead Screw Calculation

Moment required to turn the solar panel :

Weight of the solar panel setup = 15 N

Distance of CG of solar panel from shaft axis = 50mm

Moment required = W*d = 7.5N-mm

Force to lift the connection joint :

Radius of the lead screw = 3mm

Force = (Moment)/(Radius of lead screw)

Force to lift setup = 25N

Torque required to drive the lead screw:

T = (F*d/2)*((1+d)/(d-l))

Taking

Coefficient of friction for steel, = 0.15 Applying to the torque equation,

Required torque, T = 15.35 N-mm

Thus the stepper motor has a rated torque of 64 N-mm, which is well above the minimum required torque for the lead screw.

B.Slider Calculations

The required stroke length of the travelling nut is calculated from trigonometric relations :

cos(/2) = R(max)/R(min) Taking an angle, = 105 (by careful considerations) R(max) = 30/cos 52.5 R(max) = 49.28 mm Slider length = R(max) - R(min) = 20 mm Total stroke length = 2*R(max)*sin(/2) = 84mm C.Alignment Calculations

From 9am to 4pm; Total hours = 7 hrs. Angular rotation = 15 degrees per hour By ignoring the linear to angular motion inequivalency, Required displacement per hour = 84/7 = 12mm Pitch of the lead = 1mm Required revolutions per hour = 12/1 = 12mm Having a motor actuation for every 10 minutes, Required revolutions per 10 mins = 12*10/60 = 2

The required interfacing of stepper motor and microcontroller is

through simple C programming in Arduino IDE, which is imported

to the microcontroller.

The following conditions are achieved in the programming logic :

1. Two rotations per every 10 minutes from 9 a.m to 4 p.m.

2. Complete reset to the original position after 42 complete rotations.

RESULTSIn increased output is observed. Various studies from external

sources indicate an increase of output by 15-20%.

THANK YOU

QUERIES?