Designing of an Efficient Light Sensor Circuit for Competent Solar Home Systems in Bangladesh

Transcription

1 International Journal of Engineering & Computer Science IJECS-IJENS Vol:12 No:06 37 Designing of an Efficient Light Sensor Circuit for Competent Solar Home Systems in Bangladesh Ahmad Jawad *, Tawheed Hasan, Mohammod Ashraful Hoque, Ahammad Department of EEE, Ahsanullah University of Science & Technology 141 & 142, Love Road, Tejgaon Industrial Area, Dhaka-1208, Bangladesh * ahmadjawad.eee@gmail.com Abstract Stand-alone Solar Photovoltaic system is very popular in off-grid areas of Bangladesh. But recently the government is encouraging the use of solar electricity in urban areas too. Now-a-days people have to use solar systems to get electricity connection in newly completed buildings to meet certain percentage of their electricity demand. The solar electricity is stored in battery and then inverted to alternating current for use. These batteries can also be charged from the power line electricity. In this paper a light dependent switch is designed for the efficient use of solar systems. The light sensitive switch automatically charges the battery from power line after sunset, if the battery is not fully charged. The design of the switch and its analysis is presented using Yenka and Orcad Pspice package. Index Term Automatic Battery Charging, Automatic Switching, Grid Tied, Light Sensor Circuit, Solar Home System. I. INTRODUCTION Electricity plays a vital role in industry, agriculture, and transport sectors of Bangladesh but at present the electricity companies of this country can hardly meet the public demand. More than 55% people do not have direct access to electricity and although the remaining people have access, but reliable and quality power is still beyond their reach. [1] Even the power generation in Bangladesh is not sufficient enough to fulfill the demand of the urban consumers. The demand of power during daytime is now about MW and the effective generation capacity is MW. [2-3] Bangladesh has been facing a severe power crisis for a decade. Load shedding is a regular phenomenon throughout the country. [4] Power generation in the country is almost entirely dependent on natural gas, which accounts for 81.4% of the electricity generation of the total installed capacity of 5248 MW [2-3]. To fulfill the electricity demand more power generation units must be established. But burning fossil fuels emits carbon di oxide, nitrogen oxide, sulphur dioxide and other toxic metals into our atmosphere which directly causes increasing incidents of lung disease, polluting soils and waters, damaging crops. The Fig. 1 [5] below illustrates clearly that, Bangladesh is one of those countries where carbon emission is increasing day by day and for the sake of creating more power by using the limited fossil fuel would make the situation worse. Fig. 1. Carbon Emission Scenario of the World

2 International Journal of Engineering & Computer Science IJECS-IJENS Vol:12 No:06 38 Renewable energy technologies especially solar energy would be one of the most suitable for solving this omnipresent crisis of Bangladesh. Recently electricity connections are given to the new residential buildings here on condition that 3% of light and fan load has to be supplied by solar systems. [6] In this paper a new timing switch circuit is proposed for efficient use of Solar Home System (SHS). II. BASIC SOLAR HOME SYSTEMS The solar home system has following components (Fig. 2). III. THE PROJECT Fig. 3. Solar PV Modules Used In This Project Fig. 2. Basic Stand-Alone Solar Home System a) PV module (connected to a charge controller) It is used to harvest energy from the sun It is beyond question that performance of a renewable energy system is highly dependent on the environmental conditions and so a site-specific analysis is required to investigate the Light Sensor Circuit (LSC). In this work, a rooftop smart solar system with light sensitive device having low voltage alert is studied for a house situated in Kazipara, Mirpur, Dhaka. Solar irradiation data is taken for the location North and East; Sunlight Condition: Sunny; Maximum temperature: 47 C; Average temperature: 26.1 C; Average wind speed: 7.15m/s and Average rainfall: 203mm/yr. The factors of the solar system that was considered in this case is, System voltage: 12V; Depth of Discharge (DOD): 60%; Day of autonomy: 0 day; Daily sun shine: 4.5 hours; Charging efficiency: 80%; Wire loss: <3% and Module efficiency: 55-65% (considered 55%). In this research work, the module capacity is 210Wp. b) Battery (connected with a charge controller and an inverter) It is to provide energy storage or backup power in case of a power interruption or outage in the grid c) Charge Controller (connected with a solar harvester and a backup device) It limits the rate at which current is added to or drawn from the battery, prevents overcharging and may prevent against overvoltage. d) Inverter (Connected in between a battery and the AC load) It converts the system direct current (DC) to alternating current (AC) for providing energy support to the AC load e) Safety device It is to provide an automatic switching system to ensure that the SHS is running properly without any disturbance and constant monitoring Fig. 4. Charge Controller Used in this Project IV. COMPONENTS OF THIS PROJECT The detailed description of the components used in this project is described below. Previously the solar systems were not provided with safety device. In this paper a new switch is introduced which will help to increase the lifetime of the SHS. Impact of this device will be beneficial for solar systems.

3 International Journal of Engineering & Computer Science IJECS-IJENS Vol:12 No:06 39 B. Charge Controller Specification (Fig. 4) WellSee Solar Controller Ws-Al a System Voltage 12V Maximum Charging Current 15A High Voltage 14.4V Disconnect(HVD) Low Voltage Disconnect(LVD) 10.8V C. Battery Specification (Fig. 5) Fig. 5. Solar Battery Used in this Project A. PV Module Specification (Fig. 3) ZD75-12M ZD65-12M Maximum Power P max 75W 65W Open Circuit Voltage (V oc ) 21.6V 22V Short Circuit Current (I sc ) 4.7A 4.17A Voltage At Pmax (V mp ) 17.3V 17.5V Current At Pmax(I mp ) 4.34A 3.71A Tolerance Of P max +/- 3% +/- 3% Weight 8KG 6KG Fig. 6. Inverter Used in this Project System Voltage Battery Capacity Discharging Time D. Inverter Specification (Fig. 6) Power Standby consumption Inputs Outputs Output Frequency Output Voltage Power Navana Solar Power Battery 6nsp100 12V 100Ah 10Hr 300 VA 4.8 VA Screw terminals 1x Earth contact/1x Euro socket 50 Hz 230 V/AC 300 VA V. IMPLEMENTATION OF CIRCUIT The mentioned Circuit (Fig. 7) is designed and developed in the project laboratory of Ahsanullah University of Science and technology(aust). All logistics are supported by AUST. This circuit is simulated in Yenka and Orcad Pspice family package 9.2. This light sensor circuit is also energy efficient as it does not waste much energy in the circuit. One can get satisfactory output compared to what he/she has given as input. It has also been measured in the software (Fig. 8). V1 represents the light detector circuit (Fig. 9). We know, reducing the intensity of light incident on the LDR increases its resistence. This allows more current to flow through the base of the transistor, increasing the emitter-collector current and reducing the voltage at the collector. When light falls upon this LDR, current flows through the circuit and the BJT (Bipolar Junction Transistor) gets switched on and we see the LED glowing with red light. When there is no light on LDR, current does not flow in this circuit and hence the BJT remains switched off, leading the LED to remain in the OFF state. Fig. 7. Diagram of Designed Light Sensor Circuit (LSC)

4 International Journal of Engineering & Computer Science IJECS-IJENS Vol:12 No:06 40 Fig. 9. Diagram of Light Detector Circuit when Light Dependent Resister (LDR) is fully illuminated with R = 400Ω Fig. 8. Input Output Curve of Designed Light Sensor Circuit (LSC) VI. USE OF LIGHT SENSOR CIRCUIT TO AN EFFICIENT SOLAR HOME SYSTEM There are various uses of this circuit. When the intensity of the sun is enough, users get power from the solar system. This time users turn off the grid connection and connect the solar system to the load. It means that it has to be done manually. At present all SHS users operate their SHS in this manner. This paper proposes the SHS to be automated. Users no more need to switch on their solar SHSs manually. This developed Light Sensor Circuit (LSC) will automatically switch on-off the SHS. Fig. 11. Diagram of Light Detector Circuit when Light Dependent Resister (LDR) is fully darkened with R = 1MΩ Fig. 10. Diagram of Light Detector Circuit when Light Dependent Resister (LDR) is partially illuminated with R = 4KΩ Fig. 10 and Fig. 11 also shows the characteristics of this light detector circuit. When there is some light, which cannot totally illuminate the LDR leads the LED to remain OFF. When more darkness arises, LED remains at the same state. In Fig. 8 both the input and output wave shapes are plotted in the same graph. The green arrow indicates input wave shape and the red arrow indicates output wave shape. Relationship between input and output is compared in this graph using Orcad Pspice family package 9.2. It is clearly visible that the difference between the voltages of input and output of the light sensor circuit is very low. VII. LIMITATIONS OF WORK This work has been done by considering one site at Kazipara, Mirpur, Dhaka. The limited no. of resources in our hand forced us to consider minimum possible location to include in our work. If we would have the opportunity to consider quite a few number of sites then the analysis would be more enriching. VIII. CONCLUSION This LS circuit will bring a good change in SHSs. Increasing the efficiency of SHSs will be feasible with the help of this circuit. By applying this new device it will also be possible to make the solar systems economically more viable. At present, the SHSs are facing some difficulties due to not having the LS

5 International Journal of Engineering & Computer Science IJECS-IJENS Vol:12 No:06 41 circuit. People unconsciously turn on grid connection during daytime, which is sheer misuse of the grid electricity. But with this developed circuit it will be not possible to turn on national grid during daytime. In cloudy days and during nighttime, when solar intensity is not enough, this circuit will automatically turn on the national grid, which will allow us to save electricity. With this proposed device, the efficiency, longevity and performance of SHSs will be increased. In addition to this, saving money in the long run would be possible due to the longevity of the SHSs. This work s novelty lies in the discovery that the selection between renewable and grid sources will become fully automated and the performance becomes better from both a commercial and an eco-friendly point of view for a developing country like Bangladesh where grid connection is available but cannot supply the full demand of mass people. REFERENCES [1] (2012) Bangladesh Power Development Board website. [Online]. Available: [2] Bangladesh Power Development Board (BPDB), Annual Report , [3] Power Cell, Power Division, Ministry of Power, Energy and Mineral Resources, Power System Master Plan Update, [4] D.I. Swarna, A. Jawad, Ahammad, Life Cycle Assessment of Grid Tied SHSs in Bangladesh with Respect to Conventional Sources, IJECS: International Journal of Electrical & Computer Sciences, vol. 12, Issue. 5, pp , October 2012 [5] (2012) International Sustainable Campus Network website. [Online] Available: [6] (2012) Bangladesh Economic News website. [Online] Available: