Design and Implementation of a Smart Terrace Energy System 1.INTRODUCTION Project by Manaswi deshmukh, Chetan thaware, Harsh shah Savitribai Phule University Demand for more energy makes us seek new energy sources. Researches for renewable energies have been initiated first for wind power and then for solar power. Efficiencies of wind and solar power could be increased by 50% by using it as a combination.the project is all about charging the rechargeable battery with all possible available sources of energy like solar energy using maximum temperature tracking point method so that the solar panel rotates according to the position of the sun using a servo motor, wind energy using wind mills or an array of windmills using F-20X aerodynamic technology. This work is expected to sustain some part of the daily domestic electricity consumption with an efficient utilization of solar and wind power. 2. ENERGY SOURCES In the recent times the need for energy has increased globally. The electrical energy has now needed for almost everything. This has made us to increase our energy production which implies extra pressure on our nonrenewable resources. The other way is to generate energy by using renewable resources of energy. 2.1. NON-RENEWABLE ENERGY RESOURCES Non-renewable energy resources are the ones that decades for reuse, such as oil, coal and natural gas, wood. 2.2. RENEWABLE ENERGY RESOURCES Renewable energy resources are the ones that are available and which renew itself with the time. Industrialization has remarked the use of renewable energy resources. Solar power, wind power, tide power, wave power, geothermal power are known ones. 2.2.1 SOLAR PHOTOVOLTAIC PANEL : The basic working principle of a solar panel is that it contains silicon cells containing small p-n junctions inside them. The incident photons works as a free charge carriers. These charge carriers are separated through the junction and then the electric current is generated. The arrangements of the silicon cells is different which produces different levels of voltage and current. The solar photovoltaic panel is selected on the system requirements and before selecting the panel we should kept in mind that its specifications cannot be altered thereafter. The selection of the solar panel depends on the time it takes to charge the connected battery. For the calculation purpose following equation can be used: Peak hour required= V * Capacity (battery) power (SPV) This equation can also be written as: Power (SPV) =V battery *Capacity (battery) peak hour required. 14
Since there are only 12 hours of sun so, a panel will be required which can charge the battery in 12 hours initially. A solar panel generates power only for 12 hours a day. So here this wind-solar system proves useful because it can generate power at times when sunlight is not present..2.2. WIND POWER: Wind power is converted into electric power with the help of wind turbines. Electric generator inside the turbine converts the mechanical power into the electric power. Turbine systems are available having ranges of 50W to 2-3 MW. The energy production by wind turbines depends on the wind velocity acting on the turbine. Wi power is used to feed both energy production and consumption demand in the rural areas. Wind turbines can be classified with respect to the physical features (dimensions, axes), generated power. Wind turbines with respect to axis structure can be classified as horizontal rotor plane located turbines, turbines with vertical or horizontal spinning directions with respect to the wind. Turbines with blade numbers: 3-blade, 2-blade and 1blade turbines. The maximum power available through wind resource is given by this equation : P = 0.5 * ρ * A * 3 (in watts) Where P= power ρ=density of air A=area perpendicular to the flow of wind V=wind velocity The above equation only gives theoretical power and so a power coefficient has to be added with the given equation Cp =0.4. P = 0.4 * 0.5 * ρ * A * 3( in watts). Since the system is designed for low wind speeds so the wind turbine needs to be small. For the calculations assumed are diameter of the turbine is 1 metre and that gives us the area of the wave front of the turbine to be 0.785m2. For Pune the data can be calculated as follows: - ρ=1.23 (kg/m3) A=0.785m2 V=6.5m/s The power output of this system according to equation is 53.03 watts. This result is totally theoretical and the actual results may differ. 2.2.2.1 BLADE DESIGN: The construction of the wind blade starts from the design of the turbine. There are basically two types of designs: - A.HORIZONTAL AXIS WIND BLADE (HAWB): An HAWB is the most commonly used because it is more efficient because the blades are always facing against the wind. That is why we have to make maximum power out of wind but it has a drawback that we have to keep tail always in winds direction. B. VERTICAL AXIS WIND BLADE (VAWB): Whereas in VAWB there is no need of a tail but the full power of wind is not utilized in this design it is more useful for high wind speed applications. The blades have been made of normal PVC pipe. So, at the speed of 5m/s the turbine rotates at 300 RPM and that is sufficient for the system as the electrical generation will be more with increasing wind speed. The proposed system will work on both solar and wind energy. The generated dc output will be monitored by the microcontroller continuously and on getting suitable input and suitable condition the generated power is supplied to the charge storage unit. 3. DESIGN AND IMPLEMENTATION OF DOMESTIC HYBRID ENERGY SYSTEM : 15
Integration of systems has more influence in terms of electric power production. Such systems are known as hybrid systems. Hybrid solar-wind applications are implemented in the field where all energy of the year is to be consumed without any chance for an interrupt. It is possible to have any type of energy resources to supply the energy demand in such as solar and wind. This project is similar with solar panel and wind turbine power. Photovoltaic solar panels and small wind turbines depend on weather conditions. Therefore only solar or wins power is not sufficient alone. A number of renewable energy expert claims to have a hybrid energy resource if both wind and solar power are combined within a unique body. In the summer, when sun beams are strong enough at that time wind velocity is relatively small. In the winter time, when sunny days are relatively of small duration, wind velocity is high on the contrast. Efficiency of these renewable systems also differs through the year. In other words, it is needed to have these two systems with each other to accomplish the continuity of the energy production in the system. A picture of the constructed hybrid system is show in Figure. The kinetic energy of the wind is converted to the mechanical energy in the rotor. The rotor shaft speed, 1/18, is Wind turbine first converts the kinetic energy to mechanical energy and then converts it to the electricity. The wind turbines in the system are consists of tower, alternator, speed converters (gear accelerated in the reduction gear and then transmitted to alternator). The electricity which comes from the alternator can be directly transmitted to DC receivers as well as it can be stored in the batteries. MPPT regulates the energy coming from these panels and monitors a continuous high power generation. The current from the MPPT is used to charge the battery. The working of the microcontroller depends upon the input output signals provided to it by other connected circuitry. To sense the solar panel input voltage, a voltage sense circuit has been used in this project. This is the batter charger circuit who s specifications are given as below: POWER SUPPLY DESIGN : Here our requirement is 5volt for PIC, LCD, ACS712 current module, LM324. This requirement can be fulfilled by using Zener regulator. We don t require external power supply because our requirement can be fulfilled by dropping down voltage available from solar cell with the help of Zener diode as regulator. HALL CURRENT SENSOR MODULE ACS712 5A MODEL: We want to measure the current but ADC can read voltage signal only so that we have to convert the current signal into voltage signal with precision.so we are using hall effect current sensor module ACS712. The device consists of a precise, low-offset, linear Hall circuit with a copper conduction path located near the surface of the die. Applied current flowing through this copper conduction path generates a magnetic field which the Hall IC converts into a proportional voltage. The current sensor chips: ACS712ELC-5B.Pin 5V power supply, on-board power indicator. The module can be measured plus or minus 5 amps, corresponding to the analog output of 185 mv / A. There is no the detection current through, the output voltage is VCC / 2. RECHARGEBLE BATTERY : 16
Thus to store solar energy generated by the panels, we have used lead acid battery of 6V and 4.5AH.For proper charging of battery we need charging voltage slightly greater than standly mode voltage of battery which is 6.8-6.9V and supply it 7.2V. Battery charging current required=10% of 4.5AH=450ma Output of regulator IC7808 is given as input to battery and current is limited with the help of current limiting resistor. ZENER DIODE REQUIREMENTS: Total current required=38.6ma Voltage required=5v Power rating required=0.193w ZENER DIODE SELECTION: Vin=8V(From IC 7808) Rs=(8-5)/38.6mA=77.20ohm~100ohm We have selected IN751A zener diode as it satisfies our requirements. For INS751A, Vz=5.1V,500mW LM324 OP-AMP: It is used as comparator.in order to control battery charging ckt, we are comparing battery voltage available with the reference voltage which is nothing but the voltage across zener diode. When battery voltage is greater than reference voltage,output of comparator goes +ve and which turns on the transistor and then relay switches its position and stops charging. Regulator IC: Required Vout=7.2(Battery charging voltage)+0.8(diode)=8v So we have selected LM7808 which meets all our requirements. Required current is less than current capability of LM7808, so we don t need current boost ckt. SOLAR CELL: Our project is capable of measuring voltage from 0V-30V. RESET CIRCUIT: We are connecting an RC circuit to the MCLR (pin1) of the microcontroller (18F452).The resistor and the capacitors values from the datasheet are 10kohm and 22pF respectively. The resistor capacitor combination gives the RC time delay for the microcontroller for it to operate properly. The PIC has an active low reset, the capacitor initially at 0V charges via the supply through a ohm resistance in series. Therefore the reset time of our circuit is: R*C=10K*0.1*10^-6=0.22usec 17
Total power wattage requirement=5(38.6ma) + 7.2(450mA) =3.433W Total power required =3.433W CRYSTAL CIRCUIT: Here we are connecting two capacitors which are basically of values 22pF each. In other words to give a pure square wave to the microcontroller. Basic rule for placing the crystal on the board is that it should be as close as possible to avoid any interference in the clock. An LCD has also been used to guide the user about various things taking place inside the charge controller. The LCD used in this project has been used in 4-bit mode to save the pins of the microcontroller. 4. SYSTEM COSTING: The system costing is based on the price of various items that are available at the time of the installation. However the price may be different for different locations and working conditions.depending upon the cost of solar panel, wind generator,charge controller,wind turbine assembly approximate budget is rs. 5000-6000. 5.CONCLUSION: This solar battery charger is just one of the examples of solar powered devices. We are re-using batteries because we are recharging them using solar energy. By doing this we are saving the non - renewable energy source and are avoiding electrical waste. Also we are not harming the environment and we are using the natural energy sources for our energy needs. If every one of us uses such more and more solar powered devices, the energy crisis can be minimized at a very great level. By using solar devices more we are directly decreasing the rate of consumption of non -renewable sources and are making these sources available to the upcoming generations. Thus we can be self dependent at the times of wars and not depend on government power supplies during the times of wars and this will always be the most efficient source of energy as sun never dies. 18