International Journal Of Scientific Research And Education Volume 3 Issue 12 Pages-4687-4691 December-2015 ISSN (e): 2321-7545 Website: http://ijsae.in DOI: http://dx.doi.org/10.18535/ijsre/v3i12.03 Implementation of Solar Inverter for Electronic Lab Equipment Author Meenakshi Dixit 1, Dr. A. A. Shinde 2 1 M.Tech. Electronisc, 2 Dept. of Electronics BVDUCOE Pune,India Email-meenakshidixit@gmail.com, aashinde@bvucoep.edu.in ABSTRACT- Nowadays, electrical energy is one of the important needs of human being. Some energy sources such as coal, diesel, petrol etc. are used to generate electricity. But these resources are limited. Renewable energy resources such as solar energy or wind energy can be used to generate electrical energy. Solar energy is renewable energy that is found in large quantity. Proposed system uses solar energy. To avoid damage of load due to voltage fluctuation this system uses battery parallel to solar panel. The paper describes development of a 100W solar inverter for electronic laboratory equipment. The objective of this system is to design, build and test solar inverter. The solar system comprises of solar panel, charge controller, Inverter and monitoring system. This system monitors voltage and current ratings from inverter. Index Term Battery level indicator, dc-ac power conversion, monitoring using pic 18f4520, Photovoltaic systems INTRODUCTION Earth receives thousands of times more energy every day from the sun than is consumed in all other resources. This energy can be used in residential or commercial applications. Solar panel is used to collect this energy. Output of solar panel is in the form of DC. All electrically plug-in appliances work on AC supply. So it is required to convert DC energy into AC. For this conversion solar panels are being used. Solar (PV) panel is made up of collection of multiple solar cells. Solar cell consists of semiconductors. There are two types of semiconductors in PV cells: one is positively charged and another is negatively charged. When light strikes on the semiconductor, electrons are freed from negatively charged semiconductor. These electrons attract to the positively charged semiconductors and generate voltage difference. When load is connected electrons flows through the circuit and creates electricity. If intensity of light is greater, then flow of electricity is greater. Figure 1 shows i-v characteristic of solar cell. When the voltage of PV module is less than Vmp, current will drop slowly. But as the PV panel voltage increases to Vmp current will drop quickly [6]. At same time power of PV module will reach its maximum power point (MPP). As the PV panel temperature increases, voltage output decreases and vice versa. Figure 1 I-V characteristics of PV cells Meenakshi Dixit, Dr. A. A. Shinde IJSRE Volume 3 Issue 12 December 2015 Page 4687
In solar system we obtain energy using semiconductor material from the light of the sun. Solar panel does not have moving parts. It has zero emissions and no maintenance. They are used in industrial, commercial, institutional and residential applications. We can reduce the energy imports and dependence on gas and oil by constructing solar system. It reduces the risk of fuel-price volatility. Solar panel supplies energy for small-scale applications where electricity is limited and most expensive. In the present study, a solar (PV) system is proposed with simple technology that works as a standalone device. This system consists of implementation of solar inverter, charge controller and monitoring system. Section II describes the block diagram of solar inverter. II. BLOCK DIAGRAM OF SOLAR INVERTER Fig 2: Block diagram of solar inverter Fig 2 shows block diagram of solar inverter. It comprises of solar panel, charge controller, battery for storage, Inverter, peripheral device and monitoring system. System uses 75W of solar panel, 12V of batteries for storage. When solar energy falls on to the solar panel it will convert it into DC energy. By using charging circuit battery will charge in proportional with the solar energy. Charge controller controls the charging of battery and protects it from damage. Then inverter takes DC power from battery and converts it into AC power. Load is connected at the output of inverter. Voltage and current from inverter is measured by using voltage and current transformers and given to the microcontroller. Microcontroller converts voltage and current into power and display it on LCD. A. Charge controller- Charge controller is used for preventing the battery from over charging as well as from fully discharging so as to protect battery life. Charge controller also indicates battery level by using 10 LEDS. At the time when battery is charged fully it disconnects from solar input. And when battery is discharged to its lowest level it will disconnects from inverter. B. Inverter- An inverter is a device that converts electrical energy in DC form into AC. There are different types of inverters. 1. Voltage source inverter(vsi) 2. Current source inverter(csi) This system uses VSI inverter. This type of inverter is served by voltage source with low input impedance. Voltage at the output remains same irrespective of current drawn from it. PWM technique is used to produce required frequency. Solar inverters are classified as follows: 1. String inverter 2. Centralized inverter Meenakshi Dixit, Dr. A. A. Shinde IJSRE Volume 3 Issue 12 December 2015 Page 4688
3. Micro-inverter This project uses micro-inverter. In micro-inverter solution one inverter is used for one PV panel. So there is no PV mismatch. MPPT can be done at each panel level [5]. So efficiency is maximized. It is good for large production with low manufacturing cost. This technology is typically used for residential and commercial applications because that have low power requirement. This will recover panel mismatch losses as well as partial shading losses. Inverter block consists of oscillator for generating required frequency. Frequency is controlled by using PWM technique. Inverter input is 12V from battery and output is 230V 50Hz. C. Output Device: Output device can be any form of load. This system uses any one or two electronic laboratory equipment as a load. e.g. CRO. System uses solar inverter to drive the load. In case of low battery supply to load can be change from inverter to mains supply. This system can drive load up to 85W. Beyond that inverter will be automatically disconnects from load. D. Controller unit: PIC 18F4520 is used to sense the voltage and current from the inverter and display power on the LCD. Voltage and current from inverter is measured by using Voltage and current transformers. It also senses the battery level and if the battery is discharged to threshold then it displays Battery low on LCD. Microcontroller senses battery level, if battery is low then inverter will switch off automatically. As the inverter switches off, load can drive from mains supply. RESULTS Following figure shows connections of complete process to be performed. It includes different circuits such as PIC connections to various components, charging circuit, inverter circuit, change-over circuit, etc. Figure 3: circuit connection Figure below shows the battery charging level. This shows battery level is 70%. Figure 4: Battery level indicator When load is connected LCD displays power of load. Figure below shows output power when load is connected. Output of oscillator is shown below. Meenakshi Dixit, Dr. A. A. Shinde IJSRE Volume 3 Issue 12 December 2015 Page 4689
Figure 4: Output of oscillator Following figure shows the output of inverter which is taken from voltage transformer. Output of voltage transformer is 12V, 50Hz. Figure 5: Output of Inverter When load is connected LCD displays output power. Following figure shows LCD display when there is no load connected at output. Figure 6: LCD display at No load Following figure shows LCD display when 60 Watt load is connected at output. Figure 6.1: LCD display at 60 watt load Meenakshi Dixit, Dr. A. A. Shinde IJSRE Volume 3 Issue 12 December 2015 Page 4690
Observation table: Table 2: Observation table for different loads Following table shows observations for different loads. Load Theoretical Backup of Inverter (W) (H) 85 3.40 3.05 60 5.12 5.00 35 8.54 8.30 Practical Backup of Inverter (H) CONCLUSION This system is designed to operate electronic lab equipment through solar energy. The design uses solar energy that helps in reducing conventional energy generated i.e. electricity. The design requires only one time investment. This inverter can be called as smart inverter because it shows battery level. As well as when battery is low and load is greater than 85W it switches off inverter automatically. At the time inverter is off load drives from mains supply. REFERENCES 1. V.C. Kotak1, Preti Tyagi DC To DC Converter in Maximum Power Point 2. Tracker International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering (An ISO 3297: 2007 Certified Organization) Vol. 2, Issue 12, DECEMBER 2013 3. P.Murugan1, R. Sathish Kumar Simulation Analysis of Maximum power Point Tracking in Grid connected Solar Photovoltaic System IJISET - International Journal of Innovative Science, Engineering & Technology, Vol. 1 Issue 2, April 2014 pp.2348-7968 4. Sachin Jain and Vivek Agarwal, Senior Member, IEEE. A Single-Stage Grid Connected Inverter Topology for Solar PV Systems With Maximum Power Point Tracking IEEE transaction on power electronics, vol 22, No.5, September 2007.Pp.1928-1940. 5. Huang-Jen Chiu, Yu-Kang Lo A Module-Integrated Isolated Solar Microinverter IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 60, NO. 2, FEBRUARY 2013 pp.(781-788) 6. Mervin Johns, Hanh-Phuc Le and Michael Seeman Grid-Connected Solar Electronics University of California at Berkeley Department of Electrical Engineering and Computer Sciences 7. FENG TIAN Solar based single stage high-efficiency grid- connected inverter 8. www.wikipedia.com 9. www.google.com Meenakshi Dixit, Dr. A. A. Shinde IJSRE Volume 3 Issue 12 December 2015 Page 4691