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Solar charger circuit, Study Guides, Projects, Research of Energy and Environment

solar energy project

Typology: Study Guides, Projects, Research

2014/2015

Uploaded on 11/25/2015

Yasir.shah
Yasir.shah 🇬🇧

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Download Solar charger circuit and more Study Guides, Projects, Research Energy and Environment in PDF only on Docsity! Project Report on Solar Charger Circuit using IC LM317 Prepared by: Neha Kondekar Undergraduate 1st Year, Indian Institute of Science, Bangalore Guided By: Amit K Gupta, Prof. Navakant Bhat Centre for Nano science and Engineering, IISc Go Solar Table of Contents 1. Abstracts 2. Introduction 3. Theory 4. Experiments : Observations And Results 5. Summary 6. Conclusions 7. Further Interests Solar cells have come a long way from bulky 6% efficient chunks to thin films with as much as 30% efficiency. They are selling like hot cakes today given their necessity and utility. And the reason being they are faithful good chaps unlike oil which will soon be more precious to us than diamonds and the black monster: coal which has polluted the air, hand in cuff with the other fossil fuels. We need to understand solar panels so as to understand their applications. Today, we have mono- crystalline, polycrystalline and amorphous thin film panels. Mono-crystalline are so far the most efficient, given that they have the maximum silicon in a unit area so more current for the same number of photons. They are made out of a single silicon crystal as a continuous lattice. While for the polycrystalline panels, molten silicon is poured into molds and separate boundaries can be seen due to this. Lesser quantity of silicon in a unit area means lesser efficiency of production of electricity. Amorphous thin film panels are layers of silicon on a glass surface and are the least expensive. Hence, they are used in applications where you can do away with efficiency for lowering the costs. Solar panels are really useful in broad daylight but we need energy when the Sun isn’t shining above our rooftops. That’s why we need solar chargers which will store energy in rechargeable batteries. This project aims to make a solar charger using a voltage regulator IC so as to charge a Lead Acid Battery with the constant output voltage obtained through this IC LM317( Details explained later). Today there are many more options like a SOLAR CHARGER IC LT3652. This is an IC with embedded MPPT (Maximum Power Point Tracking) algorithm. MPPT simply means the IC gets the maximum possible power from the solar panel by sampling its output and applying the proper load resistance. This small chip simplifies life given its ease of use and maximum efficiency is always ensured. Source : Wikipedia Even 15% efficient solar panels installed across the world’s wasetelands can produce enough clean energy to sustain mankind for a year. Yet new technology is continuously being developed though solar energy generation is still in its infancy. The concept of SOLAR FARMING is new and catching up fast in investors. India is a tropical country and can soon become the Saudi Arabia of solar energy. With Concentrated Photo Voltaics (CPV : which increase efficiency by concentrating large amount of sunlight on the solar cells using mirrors) coming up in India, we are definitely headed towards a cleaner future. Reducing dependence on fossil fuels and cutting down on our carbon emissions is one of the most important aspects of solar energy. Another crucial point is it can make any country, especially tropical ones like India, self-sufficient in energy. With ambitious project like the National Solar missions aiming at producing 20GW (India’s energy consumption 2012: 100GW out of which 1GW was Solar energy) by 2020 is a big step toward progress. Rural areas are now lit up with solar lamps. Solar parks are also an emerging trend with Charanka Solar Park, Gujarat producing 20MW of energy. Government is also taking initiatives to encourage people to make use of the sun by subsidizing electricity bills for consumers using the solar panels. So if you make more energy than you use, you will end up in a profit without even burning a calorie! Going Solar is exciting but some challenges also need to be addressed. Space constraints, weather constraints and expensive technology involved do hinder the process. But with increase in production and development of technology, prices will fall, demands increase and we will be living in a cleaner, safer environment, making the energy we need. Renewable sources of energy alone can ensure sustainable development. Economic growth can also be ensured by energy reaching to each and every household in turn increasing the productivity of industries and standard of living of people. It is a bright future we have ahead of us; the only thing is we need to focus the glare rather than evading it. Theory This project aims to make a solar charger circuit using IC LM 317 which is an adjustable voltage regulator. SOLAR PANEL, 5W, 17.5V, 362X163X8MM Power Rating: 5W Power Voltage Max: 17.2V Current at P Max: 290mA Open Circuit Voltage: 21.4V Short Circuit Current: 320mA Solar Battery charger IC(LT3652) Battery: Li-ion(3.7V,1400mAh) IC LM 317 : Adjustable Voltage Regulator so as to have constatnt voltage charging for the battery Lead Acid Battery ; 6V, 5Ah Zener diode : To cut off charging after battery reaches saturation applications like our solar lamp, they are good enough. Care must be taken while handling acid batteries. • Diodes(1N5812): These are simply blocking diodes which ensure that the current flows only in one way so that the battery doesn’t discharge when the output from solar panel is low. • Zener Diode(1N4736) and the Transistor(BC548): This part of circuit ensures that once the charging cut off voltage is reached by the battery, the charging stops. The Zener is rated at 6.8V as breakdown. This allows all the voltage to drop across the Zener and the transistor switches on due to biasing of the Base-Emitter junction. The transistor acts like a switch and once the battery is charged, it draws all the current thus protecting the battery. Experiments Note: We conduct experiments step by step to understand how each component works and then assemble the circuit together. 1. TO study how solar panels behave to different intensities of light Conditions Open circuit voltage across the panel Covered with cardboard 0.263V Facing the desk 0.468V Covered with Paper 2.5V At the window(11am) 14.72V In the lab 7.62V At the desk 5.2V Using a torchlight at distance 15cm 11.22V At the terrace(2pm) 21.2V(maximum Voc=21.4V) Observations: Solar panels are heavily dependent on the intensity and the nature of light falling on them to produce any kind of voltage. The output varies right from 0.2V to 21.2V. Conclusions: Sunlight matters a lot. So to make the best out of a fixed solar panel, we need to have some kind of power tracking which will always allow the panel to produce a maximum power by impedance matching (external resistor across the cell). 2. To study the working of IC LM317(using power supply) Conditions: R1=180Ohm, R2=500ohm Vin Vref Vout Vin- Vout Iref(mA) Iadj(uA) 6.85V 1.225 4.64V 2.12V 6.81 19 8.30V 1.225 4.657V 3.67V 6.815 53 10.59V 1.224 4.65V 4.65V 6.815 46.6 12.16v 1.225 4.667V 4.667v 6.81 73 15.68V 1.225 4.68V 11.00V 6.81 99 23.67V 1.225 4.651V 18.19V 6.817 41 Using Solar panel Conditions: R1=180Ohm, R2=500ohm Vin Vref(V) Vout Iref(mA) Iadj(uA) 4.85V 1.225 4.64V 6.81 19 6.30V 1.225 4.657V 6.815 53 7.59V 1.224 4.65V 6.815 46.6 8.16v 1.225 4.667V 6.81 73 10.68V 1.225 4.68V 6.81 99 11.67V 1.225 4.651V 6.817 41 Observations: The output voltage from the IC is observed to be nearly constant with the input- output differential voltage ranging from 2.1V to 20V (Power supply limit). Results: IC LM 317 gives a regulated output for a particular range of input voltage. 3. To understand the working of LEDS Conditions: R1=120ohm, R2= 500ohm Observations: LED starts glowing with voltage across it>2.67V. Maximum Intensity at Vled=3.2V(Supply 25V). At that point, current through the LED=49.7mA. After that the LED blows out. So the LED is rated at 2.6V, 49mA practically. 4. To study working of Zener Diodes Setup: The Zener is tested for its rating using a power supply, LED and a resistor. The Zener conducts only after the voltage across it is>6.78V (i.e. reverse breakdown voltage). This is easily seen when the LED lights up. Observations: (Series resistor:1k) Vin Vzener Led status 1V 0.3V OFF 3.2V 2.1V OFF 6.4V 4.5V OFF 10.5V 6.77V ON 12V 6.77V ON After 15mins, Observations: Voc Vpanel Ipanel Vin(IC) Vop(IC) Vbattery(initially) After 10min After 15min Icharging 16.7V 7.961V 10mA 7.717V 6.228V 5.996V 5.997V 5.998V 1.733mA Results: The sun simulator gives an input of 7.961V to the circuit. But this limits the output voltage only to 6.228V hence the charging voltage is reduced too. This causes a charging current of 1.733mA which charges the 5Ah battery very slowly. Conclusions • Solar panels are as good as power supplies of an average of 12V in bright sunlight. The only problem is unregulated voltage due to variation in intensity of light. • IC LM 317 solves the problem by regulating the output voltage but it again dissipated 2V across it which makes the system less efficient • Solar charger circuits need voltage regulators so as to charge the batteries at constant voltage. • The battery charging process should be stopped once it is fully charged and this is ensured using a zener which will start conducting at the cut off voltage. • The charger circuit is a simple, ready to use lead acid battery charger and is a good way to tap sun’s energy on the go. Summary • Solar energy is a clean energy source and it is high time we understand its importance and embrace it in our daily lives. • Solar cells are the heart of any circuit. In the circuit for this project, Solar panels were used as a power supply and fed into a voltage regulator so as to have a constant voltage charging for the battery. • Batteries are the easiest way to store energy. Hence solar charger circuits aim at charging batteries rather than driving components. • Rechargeable batteries like Lead Acid, Li-ion and NiMH are used depending on the user’s requirements. Here we have used sealed Lead Acid ones. • It is also very necessary to cut off charging once the battery is fully charged. This is managed using a zener diode which switches on at the cut-off voltage and diverts the current through the transistor. • The battery is thus charged at constant voltage and at desired rate depending on the amount of current supplied. • Solar energy is the most abundant but least used source of energy. But it’s the solution to most of our problems • The major challenges we face in going solar is expensive technology, limited space and energy. We need to address them by having more efficient materials and most importantly awareness among people so that they use it to their benefits. References • www.main.org/polycosmos/glxywest/vimanas.htm - Indian Flying Machines • http://www.triplepundit.com/2011/08/solar-farming-potential-india/ - Solar Farming • http://en.wikipedia.org/wiki/Solar_cell • http://www.planetarypower.com.au/solar_panels.htm • http://www.earthtimes.org/energy/solar-cells-future/1403/ • Element14 – to look up devices, ICs • Physics of Solar Cells- A Text for Undergraduates, J Nelson Further Interests I am interested in learning how to make easy, portable and ready to use devices which run on solar power. The scope of imagination is large as solar power can run anything on DC voltage. Specifically, I want to explore solar chargers in greater detail and understand how to increase efficiency of power generation (IC LM317 drops the precious 3V across it thus wasting energy). Another area of interest Is exploring different technologies available in making solar cells( Mono-crystalline, Polycrystalline, Thin Films) and be able to explain why their efficiency changes so much by understanding their crystal structures.
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