Introduction

Solar energy, radiant light and heat from the sun, is harnessed using a range of ever evolving technologies such as solar heating, solar photo-voltaic solar thermal electricity, solar architecture and artificial photosynthesis.

Solar Irrigation, a new emerging application in Solar Energy as well as Solar PV Industry, is now being implemented by many companies from India. Indian government and NGOs have come forward to support this technology financially and morally.

What is solar irrigation?
Well, it’s not so complex. It is a process in which the water-pump which is used by farmers to water their crops land and helps them significantly in irrigation work, will be powered by Solar PV array, with or without inverters (and battery bank, if needed).

Need of the 'Smart Irrigation System'

India is an agricultural country. Agriculture is the primary source of livelihood in rural areas. In our country 64% cultivated land is dependent on monsoons and we receive heavy rainfalls of short duration.

If not by excessive rainfall, farmers sometimes over-irrigate their fields. Excessive watering damages the crops and reduces the quality and quantity of the crops.

Water shortage leads to below average crop yields.

Thus, these two states cause an instability in the output levels of the crops.

Moreover, about 70% of our population depends on agriculture and one-third of our national income comes from agriculture. So, in order to utilize our resources efficiently we need a system that ensures proper irrigation and the quality of the crops. And that system is the 'Smart Irrigation System'.

The Smart Irrigation System

The smart irrigation system is different from the present solar irrigation systems. The present systems utilize solar energy to power the motors. But our system does more than that. And this is how-

• In addition to the usage of solar panels for powering the motors our system allows water in the field only when the field is dry, thereby, avoiding any crop damage due to over irrigation.

• Uses harvested rain water (initially) to irrigate the fields, thereby, conserving water and electricity.

• It is a zero carbon emission project.

The Project

The system has 4 basic modules:

1) Solar Module

2) Sensors

3) Pumps

4) Circuitry

(1) SOLAR MODULE

(2) SENSORS

We've used a total of 4 sensors. 3 for moisture sensing and 1 for rain water level sensing. One terminal of the sensors is grounded and the other is connected to a transistor circuit.

When the land is dry then there is no connection between both the terminals and the transistor circuit gives a logic high output (converted by ADC) to the micro-controller.

When water flows and the soil becomes wet then both the terminals get connected and the transistor circuit is grounded. Thus, logic 0 is given to the micro-controller. The micro-controller makes the decision on the basis of these inputs and the code.

(3) PUMPS

For the purpose of demonstration we have used A.C. pumps. In the fields, submersible pumps or turbine pumps may be used.

Submersible Pumps:

Submersible pumps are installed completely underwater, including the motor. The pump consists of an electric motor and pump combined in a single unit. Typically the pump will be shaped like a long cylinder so that it can fit down inside of a well casing. Although most submersible pumps are designed to be installed in a well, many can also be laid on their side on the bottom of a lake or stream. Another common installation method for lakes and rivers is to mount the submersible pump underwater to the side of a pier pile (post). Submersible pumps don't need to be primed since they are already under water. They also tend to be more efficient because they only push the water, they don't need to suck water into them. Most submersible pumps must be installed in a special sleeve if they are not installed in a well, and sometimes they need a sleeve even when installed in a well. The sleeve forces water coming into the pump to flow over the surface of the pump motor to keep the motor cool. Without the sleeve the pump will burn up. Because the power cord runs down to the pump through the water it is very important that it be protected from accidental damage. You wouldn't want a boat tangled up in the cord or a snapping turtle or alligator to bite through it!

Turbine Pumps:

A turbine pump is basically a centrifugal pump mounted underwater and attached by a shaft to a motor mounted above the water. The shaft usually extends down the center of a large pipe. The water is pumped up this pipe and exits directly under the motor. Turbine pumps are very efficient and are used primarily for larger pump applications. Often they consist of multiple stages, each stage is essentially another pump stacked on top of the one below. It works like a train with multiple engines hitched together pulling it, each stage would be a engine. Turbine pumps are typically the type of pumps you see on farms. When you see a huge motor mounted on its end and a pipe coming out sideways below the motor, that is most likely the motor for a turbine pump down inside the well. The turbine pump is mounted in a large concrete vault with a pipe connecting it to the lake. The water flows by gravity into the vault where it enters the pump. The pump motors are suspended over the vault on a frame. A jet pump is similar to a turbine pump but it works by redirecting water back down to the intake to help lift the water.

(4) CIRCUITRY & CODE

Note: This is not the actual connection diagram as PIC16F72 wasn't available in my ISIS library, although, this is the basic circuit diagram.

COMPONENTS & SPECIFICATIONS:

PROGRAMMING:

Code : Smart Irrigation System

The code is pretty simple. First, the ADC converter is activated, the input and output ports are set (PORT B is used for interfacing the LCD, Pin no. 2 and 3 of PORT C are used for providing the output to the ULN 2003A IC, Pin no. 4, 5 & 6 for inputs from moisture sensors and Pin no. 7 for input from rain water level sensor) and the LCD is initialized.

Then the condition of the three moisture sensors is checked. If they are dry i.e. their output is logic '0'
if((PORTC.F4 == 0)&&(PORTC.F5 == 0)&&(PORTC.F6 == 0))
then the program checks whether there is water in the rain water tank. If the output of the rain water level sensor is logic '1'
if(PORTC.F7 == 1)
then it means that there is water in the tank and the irrigation will start.

As soon as the moisture sensors become wet they give output as logic '1'
if((PORTC.F4 == 1)&&(PORTC.F5 == 1)&&(PORTC.F6 == 1))
the irrigation is stopped and 'Irrigation done' is displayed on the LCD.
Lcd_Cmd(_LCD_CLEAR);
Lcd_Out(1,4, "IRRIGATION");
Lcd_Out(2,7, "DONE");

If the output of the rain water level sensor is logic '0'
if(PORTC.F7 == 0)
then ground water is used for irrigation.

This enables the water to get in the field only when it is required.

Working

The working of the micro-controller was explained above in the coding section. Now, the output from the micro-controller is sent to IC ULN2003A. It is basically a transistor array and is used for giving proper signals to the relays. It inverts the output. The signal is then transmitted to the relay which drives the respective motor.


The following flowchart explains the complete working-

Animation-

Model-

Advantages

• Energy conservation
• Ground water conservation
• Environment friendly
• Fully automatic
• Protects fields from over irrigation
• Ease of use
• Cost effective
• Low maintenance

Benefits to the farmers

• No fuel costs & minimal maintenance costs
• More economical than present systems in the long run
• Enables cultivation of extra crops 
• Helps in providing critical protective irrigation in water scarce areas
• Saves time and labor 
• Improves agriculture productivity 
• Improves general quality of life with higher levels of income

Further Developments

• The efficiency and worth of this system can be increased by using a solar tracker system. A solar tracker is a device that orients a payload towards the sun.

• Use of bi-directional pumps can facilitate the removal of excess water from the fields (due to floods, rain, etc.)

Conclusion

The projected population of India being 1500 million by 2050 and agriculture remaining as the primary source of livelihood in rural areas, the focus should be on increasing the productivity.

Though our country claims to have developed in terms of science and technology, erratic power supply has almost become our routine now-a-days. India has a huge untapped solar off-grid opportunity and also receives heavy rainfall.

So, why not utilize what we have to increase the growth rate of our country and take it towards prosperity?

The Module & The Team

Links

Full Report
Code

Glimpses