3KVA HYBRID SOLAR POWER SYSTEM BY OGBEKWE THEOPHILUS C

3KVA HYBRID POWER SUPPLY SYSTEM FOR 18-UNIT COMPUTER LABORATORY BY OGBEKWE THEOPHILUS C ABSTRACT In Nigeria presently, electrical power generated presently is grossly insufficient in terms of meeting the power demand in the country. Presently, the Information and Communication Technology (ICT) laboratory of the Electrical Electronic Engineering department depends solely on the central diesel generator for the Faculty of Engineering building which comes on at 10:30am and goes off at 4:00pm daily. Therefore there is need for alternative power supply system in order to reduce over-dependency on the utility grid. This project proposes a 3KVA hybrid power supply system for powering of the departmental Information and Communication Technology (ICT) laboratory. Based on load calculations for ICT laboratory, the system requires a 3KVA power inverter which converts power from 8 units of 24V/200AH deep cycle battery into AC power, 6 units of 300W solar panel for recharging the batteries through a 45A solar charge controller. The design procedure adopted includes various sizing calculations used to determine the required battery capacity, power rating of the solar panels and the inverter capacity. Also a new cable layout was designed for the eighteen (18) units of computers due to the insufficient funds, an incremental approach was adopted for achieving the required inverter capacity. Based on this approach, an initial 1500W inverter with 24V/100AH battery capacity and 560W solar panel array were installed to drive the 18 units of computer in the laboratory. Subsequently, another 1500W is expected to be installed in the future to take care of future load in excess of 1500W. The test results show that it took about two hours (2hrs) to discharge the battery under 761W load and five hours (5hrs) to fully charge back to 27.2V. It was observed that the intensity of the sunlight had great impact on the rate of charging of the battery. The results show that this solar installation can be used to compliment power supply for the ICT laboratory especially during power outages and downtimes of the central generator. CHAPTER ONE INTRODUCTION 1.1 Background The world today is a global village. Kudos should be given to “technology” and also to those who have brought this technology to limelight. Technology is growing at a pace that no one has been able to measure or quantify accurately. We have witnessed the invention of machines, electricity e.t.c by men who have simply applied their ideas to create something tangible and beneficial to the human race and the world at large. Michael Faraday was recognized as one of the leading scientist who made electricity viable for use in technology. In 1832 Faraday was able to prove that the electricity induced by a magnet and the voltaic electricity produced from a battery were all the same. During his time no one ever imagined that it would be feasible to generate electricity making use of renewable resources like the sun, wind e.t.c. We have seen today that electricity can be generated by so many ways. It has been shown that electricity can be generated using water (Hydroelectricity), Wind, Sunlight, Generators e.t.c. Generating electric power by placing photovoltaic cells under the sun is one of the fastest growing technologies in the power industry. This is because of the numerous advantages attached to solar power generation. Generating electric power using the sun’s power may be quite expensive, however, it is pollution free, flexible, and to an extent affordable [1]. 1.2 Problem Statement It is a general saying that necessity is the mother of invention. In reality, a problem simply creates a need for something. The sun offers the most abundant, reliable and pollution-free power in the world. However, problems with solar energy, namely the expensive cost and inconsistent availability, have prevented it from becoming a more utilized energy source. What is hampering solar power has everything to do with cost. It is five to eleven times more expensive to produce electricity from the sun than it is from coal, hydro or nuclear sources. This is because when there is a defined problem, it automatically means that a need has been created and finally a solution has to be created to meet this need. Growing up as a child in a neighborhood that is constantly faced with erratic power supply ignited the idea in me to create a system that is viable and renewable that can provide electricity anytime so as to solve the problem of erratic power supply. In such neighborhoods, even when it is dark, people still have to move or make some errands. In the dark cars still move in the neighborhood and it becomes dangerous with cars flashing their headlamps so bright that pedestrians can hardly see the surface of the road. If there was a street light, cars would not have to flash their headlamps so bright. Even in school environment there is a problem with powering most of the electrical gadgets like the computers, the laptops and also most of the lightning points. This trend is the main motivation behind this project which allows the solar panels to be viewed as of the best options to solve such problems. The use of the sun’s energy to provide electricity goes a long way to solve this problem owing to the fact that the sun is free of charge, pollution free and renewable. In a nutshell, the decision to design a solar power system for powering the ICT (Information and Communication Technology ) laboratory as a final year project was actually to meet the demands of the problem highlighted above which is found in some institution and neighborhood. 1.3 Aim and Objective of Study The objective of this project is to develop an important power system that will power a load of 3kva in ICT (Information Communication Technology) laboratory room. 1.4 Scope of the Study The scope of this work shall cover these areas. The work will cover the selection of solar charge controller, battery, inverter system and inter-connectors (cable) based on the requirement of the system. Design analysis of the solar panels. The economic analysis (bills of engineering measurement and evaluation). Testing and experimentation of the system. 1.5 Justification of the Study This work entails the design and construction of a solar power system that can power a load of 3KVA to power ICT (Information Communication Technology) laboratory room. Solar power system serves as alternative source of electrical power supply which is needed in the institution at large. 1.6 Limitation The capital (cost) of setting up a standard 3KVA system was a great problem due to insufficient funds and capital available and 1500W was installed instead. The proposed 3KVA will be completed once the funds are complete. CHAPTER TWO LITERATURE REVIEW 2.1 Overview of Solar Powered System The project actually involves the design and installation of 3kva solar power system for powering of ICT (Information and Communication Technology) laboratory room. However, the designer never included a solar panel in his final design as it was stated that the solar panel is quite expensive. This project utilizes a solar panel, an inverter, a rechargeable battery and finally a solar charge controller. Fig: 2.1 shows a typical solar power system. Figure 2.1: Typical Solar Powered System [2] 2.2 Types of Residential Solar Power System There are three main types of residential solar electric power systems: grid inter-tied; grid inter-tied with battery backup; and off-grid. These three broad types vary in how closely connected they are to the traditional power utility infrastructure, known as the grid. Each type has strengths that determine how suited they are to your needs [3]. 2.2.1 Grid Inter-Tied Residential Solar Power System A grid inter-tied solar power system is directly connected to the home and to the traditional electric utility grid. Grid inter-tied systems allow the homeowners to get power from either the home electric system or the utility grid. Switching between the residential system and the grid is seamless. The prime advantage of this type of system is the ability to balance the system production and home power requirements. When a grid inter-tied system is producing more power than the home is consuming, the excess can be sold back to the utility in a practice known as net metering. When the system is not producing sufficient power, the home can draw power from the utility grid. Grid inter-tied systems are the lowest cost type of residential solar electric system, due to having fewer required components [3]. 2.2.2 Grid Inter-Tied Residential Solar Power System with Battery Backup A grid inter-tied solar power system is also connected to the traditional utility power grid and adds battery-backup to the system. The addition of a battery backup enables the system to balance production and demand and protects against power outages. Solar electric system production depends on the available sunlight. When sunlight is abundant, production can exceed demand. When production exceeds demand, the excess power can charge the batteries, which store the electricity. When the system is producing less electricity than demanded by the home, the batteries can make up the shortfall. Grid Inter-tied systems are also connected to the utility power grid. This enables the homeowners to draw from the grid during periods of excess demand and to sell power to the grid when there is excess production. While grid inter-tied systems offer more flexibility, they are not without disadvantages. Charging and discharging batteries reduces the overall efficiency of the system and these systems are more complex to design and install and therefore more expensive [3]. 2.2.3 Off-Grid Solar Power System An off-grid residential system is completely disconnected from the traditional electric power grid. Without a connection to the utility grid, batteries are essential to balance periods of excess production and excess demand. To protect against shortfalls of power when the solar system is under-producing and the batteries are discharged, an electric generator is usually added to the system. The generator is used as a power source during periods of prolonged excess production or unusual demand [3]. 2.3 The Solar Charge Controller A solar charge controller manages the power going into the battery bank from the solar array.  It ensures that the deep cycle batteries are not overcharged during the day, and that the power doesn’t run backwards to the solar panels overnight and drain the batteries. Some charge controllers are available with additional capabilities, like lighting and load control, but managing the power is its primary job [4]. The solar controller in this report is actually divided into two parts namely the charge controller phase and the low voltage disconnect phase. Fig: 2.2 shows a well labelled diagram of a solar charge controller. The charge controller phase is responsible for controlling the charging rate of the battery so as to avoid over charging or over discharging the battery. The low voltage disconnect phase is responsible for disconnecting the load from the entire circuit when the batteries voltage falls short of the load requirement. Figure 2.2: Solar charge controller [4] 2.4 Types of charge Controller A solar charge controller is available in two different technologies, PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking). How they perform in a system is very different from each other [4]. 2.4.1 PWM Solar Charge Controller A PWM solar charge controller stands for “Pulse Width Modulation”. Pulse-Width Modulation (PWM) comes into play when the battery bank is full. During charging, the controller allows as much current as the PV panel/array can generate in order to reach the target voltage for the charge stage the controller is in. Once the battery approaches this target voltage, the charge controller quickly switches between connecting the battery bank to the panel array and disconnecting the battery bank, which regulates the battery voltage holding it constant. This quick switching is called PWM and it ensures your battery bank is efficiently charged while protecting it from being overcharged by the PV panel/array [5]. Figure 2.3: PWM Solar charge controller [6] 2.4.2 MPPT Solar Charge Controller An MPPT solar charge controller stands for “Maximum Power Point Tracking”. Maximum Power Point Tracking features an indirect connection between the PV array and the battery bank. The indirect connection includes a DC/DC voltage converter that can take excess PV voltage and convert it into extra current at a lower voltage without losing power. MPPT controllers do this via an adaptive algorithm that follows the maximum power point of the PV array and then adjusts the incoming voltage to maintain the most efficient amount of power for the system. [5]. Figure 2.4: MPPT solar charge controller [7] 2.5 The Solar Panel or PV (Photo Voltaic) Arrays Solar panels are devices that convert light into electricity. They are called "solar" panels because most of the time, the most powerful source of light available is the Sun, called Sol by astronomers. Some scientists call them photovoltaic which means, basically, "light-electricity" [8]. Figure 2.5: General layout of a solar panel [9] A solar panel is a collection of solar cells. Lots of small solar cells spread over a large area can work together to provide enough power to be useful. The more light that hits a cell, the more electricity it produces [8]. Fig: 2.5 shows the layout of a solar panel. 2.6 Types of Solar Panel The sun is not only a truly reliable and lasting energy source but also a very cost effective and efficient one, if the chosen types of solar panels and the environment are perfectly matched to one another. Such promising prospects have grown in an industry that has put a lot of effort into developing efficient techniques to generate, use, and store the sun’s energy by using different types of solar panels and converting the sunlight into valuable electricity [10]. There are two major types of solar panel which include Monocrystalline Solar Panels (Mono-SI) and Polycrystalline Solar Panels (p-Si) 2.6.1 Monocrystalline Solar Panels To make solar cells for monocrystalline solar panels, silicon is formed into bars and cut into wafers. These types of panels are called “monocrystalline” to indicate that the silicon used is single-crystal silicon. Because the cell is composed of a single crystal, the electrons that generate a flow of electricity have more room to move [11]. Fig. 2.6 shows the diagram of 300W polycrystalline solar panel for the design. Figure 2.6: A monocrystalline solar panel [11] 2.6.2 Advantages of Monocrystalline Solar Panel High efficiency Low-light performance Quick response to temperature Changes High life time value Lower size 2.6.3 Disadvantages of Monocrystalline Solar Panel Very expensive If the solar panel is partially covered with shade, dirt or snow, the entire circuit can break down. 2.7 Polycrystalline Solar Panel Polycrystalline solar panels are also made from silicon. However, instead of using a single crystal of silicon, manufacturers melt many fragments of silicon together to form the wafers for the panel. Polycrystalline solar panels are also referred to as “multi-crystalline,” or many-crystal silicon. Because there are many crystals in each cell, there is to less freedom for the electrons to move. Fig: 2.7 shows the diagram of polycrystalline. As a result, polycrystalline solar panels have lower efficiency ratings than monocrystalline panels [10]. Figure 2.7: Polycrystalline solar panel [12] 2.7.1 Advantages of Polycrystalline Solar Panel Less expensive 2.7.2 Disadvantages of Polycrystalline Panel Sensitive to high temperature only Lower life span Slightly less space efficiency. 2.8 Solar Batteries Solar batteries are used to store solar energy (solar electricity). Solar Battery discharge power as and when needed. Rechargeable solar batteries are used in off-grid PV systems to store excess electricity. Some solar battery banks use wet cells, while others use sealed or gel cell batteries. Some solar battery banks use wet cells, while others use sealed or gel cell batteries. Each of these batteries have different temperature, mounting, and ventilation requirements. Plate: 2.1 shows the battery voltage for this project which is 12V/100AH. In this project, it can be seen that the battery here is used to supply power to the load through the inverter. During the day when the sun is still shining, the photovoltaic panel simply charges the battery so that in the night or during hours of no sunlight the battery can still supply power to the load [13]. Plate 2.1: 12V 100Ah solar battery connected in series 2.9 Types of Solar Batteries Lead Acid Batteries Nickel –Cadmium (Ni - Cd) Batteries Nickel – Metal Hydride (Ni MH) Batteries Lithium Ion Batteries Lithium Polymer Batteries 2.10 Lead Acid Batteries Lead acid batteries are the common energy storage devices for PV systems. Lead acid batteries can be either 6V or 12V type in tough plastic container. The batteries can be flooded cell type or sealed/gel type [13]. 2.10.1 Flooded Cell Type Battery This is the most commonly used type of battery for renewable energy systems today. Flat and Tubular plate type are the versions of flooded batteries. In flooded batteries the electrodes are completely submerged in the electrolyte. During charging of flooded batteries to full state of charge, hydrogen and oxygen gases produced from water by the chemical reaction at negative and positive plates passes out through vents of the battery. This necessitates the periodic water addition to the battery [13]. 2.10.2 Sealed /Gel Type Battery These batteries have immobilized form of electrolyte. The sealed maintenance free lead acid batteries are also called as valve regulated lead acid (VRLA) batteries or captive electrolyte lead acid batteries. The sealed batteries are of two types namely gelled electrolyte type and absorbed glass mat type. Immobilized electrolyte batteries will have less electrolyte freeing problems compared to flooded electrolyte batteries. During charging process, hydrogen and oxygen gases are produced from water due to chemical reactions at the negative and positive plates. These gasses recombine to form water, thus the need for water additions is eliminated [13]. This type of lead acid batteries is suitable for PV applications because of the following reasons: Easy transportation. Suitable for remote applications because of less maintenance requirement. No need for water additions. 2.11 Gelled Batteries The addition of silicon dioxide to the electrolyte forms a warm liquid which is added to the battery and become gel after cooling. The hydrogen and oxygen produced during charging process are transported between positive and negative plates through the cracks and voids in the gelled electrolyte during the process of charge and discharge [13]. 2.12 Absorbed Glass Mat [AGM] Batteries In AGM batteries the glass mats are sandwiched between plates. These glass plates absorb the electrolyte. The oxygen molecules from positive plate moves through the electrolyte in the glass mats and recombine hydrogen at the negative plate to form water. Both gel and AGM batteries require controlled charging. In this batteries generally Lead calcium electrode are used to minimize gassing and water loss. Voltage and current must be controlled below C/20 rate [13]. 2.12 Nickel –Cadmium (Ni - Cd) Batteries In Ni-Cd battery positive electrode is made up of cadmium and the negative electrode by Nickel hydroxide separated by Nylon separators immersed in potassium hydroxide electrolyte placed in a stainless steel casing. It has longer deep cycle life and temperature tolerant compared lead-acid battery. Cadmium is replaced by metal hydrides due to environmental regulatory rules. Memory effect degrades the battery capacity when the battery is idle for long time. Memory effect is the process of remembering the depth of discharge in the past. If the battery is discharged to 25% repeatedly, it will remember it, and if the discharge is greater than 25%, the cell voltage will drop. To recover the full capacity the battery, it should be reconditioned by fully discharging and then fully charging once in few months [13]. 2.13 Nickel – Metal Hydride (Ni MH) Batteries It is an extension of Ni-Cd batteries with high energy density. The anode is made up of metal hydride instead of Ni-Cd. It has less memory effect and delivers high peak power. It is expensive than Ni-Cd batteries and overcharging damages the battery easily [13]. 2.14 Lithium Ion Batteries The energy density of Li-ion batteries is 3 times that of Pb-acid batteries. The cell voltage will be 3.5V, and few cells in series will give the required battery voltage. The lithium electrode reacts with the electrolyte creates a passivation film during every discharge and charge operation. This is compensated by the usage of thick electrodes. Because of this fact the cost of Li-ion battery is higher than Ni-Cd batteries. Further overcharging damages the battery [13]. 2.15 Lithium Polymer Batteries In this battery solid polymer electrolyte acts as both electrolyte and separator and the lithium electrode reaction with the electrolyte is less [13]. 2.16 The Solar Inverter System A solar inverter or PV inverter, is a type of electrical converter which converts the variable direct current (DC) output of a photovoltaic (PV) solar panel into a utility frequency alternating current (AC) that can be fed into a commercial electrical grid or used by a local, off-grid electrical network. Fig: 2.9 shows the diagram of an inverter system. It is a critical balance of system (BOS)–component in a photovoltaic system, allowing the use of ordinary AC-powered equipment. Solar power inverters have special functions adapted for use with photovoltaic arrays, including maximum power point tracking and anti-islanding protection [14]. Plate 2.2: 1500W Solar Inverter 2.16.1 Types of Solar Inverter System Basically, there are two types of inverters out there in the market The Stand-alone inverters and The Grid-tie inverters. 2.16.2 The Stand Alone Inverters Stand-alone inverters, used in isolated systems where the inverter draws its DC energy from batteries charged by photovoltaic arrays. Many stand-alone inverters also incorporate integral battery chargers to replenish the battery from an AC source, when available. Normally these do not interface in any way with the utility grid, and as such, are not required to have anti-islanding protection [14]. 2.16.3 The Grid Tie Inverters Grid-tie inverters, which match phase with a utility-supplied sine wave. Grid-tie inverters are designed to shut down automatically upon loss of utility supply, for safety reasons. They do not provide backup power during utility outages [14]. CHAPTER THREE METHODOLOGY 3.1 Design Procedure This chapter covers the major components that are used in the circuit design of this project, the block diagram of the design, the circuit diagram of the design work including the design calculations and considerations. The block diagram of the proposed hybrid power system for ICT laboratory is shown in fig 3.1. Figure 3.1: Block diagram of the solar power system for ICT laboratory 3.2 The principle of operation of the system The solar power system in fig. 3.1 is the typical block diagram showing the major components of the solar power system for the ICT (Information Communication Technology) laboratory. When sunlight strikes the PV panel, it converts this sunlight directly into DC electricity. The charge controller allows this DC electricity to start charging the battery. The inverter helps to convert the DC power supply from the battery to AC so as to be able to power the AC loads. 3.2 Major System Components The major components of the systems are; The PV module The solar batteries The charge controller The inverter system 3.3 Determination of Load Demand In order to size the solar system correctly, the power rating of each appliance that will be drawing power from the system. Table 3.1: Determination of Load Demand for ICT laboratory S/N Items Qty Power(W) Total Watts(W) Diversity Factor Diversity factor × Total watts Hours per Day(H) Total Hours per day(WH) 1 Ceiling Fan 3 50 150 1 150 4 600 2 LED Lamp 6 15 90 0.6 54 5 270 3 Standing Fan 1 150 150 0.6 90 2 180 4 LCD Monitor 10 100 1000 0.6 600 4 2400 5 CPU 10 150 1500 0.6 900 4 3600 6 Laptop 8 65 520 0.6 312 4 1248 2106W 8298WH 3.3.1 Sizing of the Inverter From table 3.2, it can be seen that the peak demand is 2106W, thus the inverter needs to be able to deliver this power. It will thus be logical to use a 3kW inverter. Note: Inverter must always be higher in capacity than the maximum demand. 3.3.2 Sizing of the PV Array (Solar Panel) Accordingly to table 3.2, system will use approximately 8298W hour per day. Then there is need to generate more energy than you use. The effective charging hours per day vary as per location, the further north you are the more effective hours of charging per day you have. Effective charging hours is based on the exposure to the sunlight, which is lower in the rainy season and higher in the summer/dry season and is based on average of a year. Depending on the angle of the panels it is more likely to get better performance in summer/dry season than rainy season or vice versa. Let's assume we have an average of 5 hours charging per day. If we increase the 8298Wh per day to say 9000Wh (to Allow for some extra charging), the amount of panels we will need is [15]: (3.1) 9000W.h/ 5 Hours = 1800W (3.2) Thus we need 1800W of solar panels. If we use 280W panels, that would mean 1800W/280W = 6.42 ≡ 7 panels If we use 300W panels, that would mean 1800W/300 = 6 panels (3.3) So the desired number of the solar panel for the design is 6 panels, each rated at 300W. 3.3.3 Sizing of the Batteries An inverter has a rating and it is not usually good to load the inverter up to the 75% of its rating [15]. Total load demand (WH) = 9000Wh (3.4) Efficiency = (3.5) Input = = 9473.7Wh (3.6) To determine the system voltage, we use a standard [16]; 1Kva – 2.5KVA = 24V/48V 3Kva – 10KVA = 48V/120V The total energy demand in watt hour = 9473.7Wh The system voltage for the design = 48V The charge demand = = = 197.4Ah (3.7) Battery capacity = (3.8) 329Ah Battery to use for the design = 200Ah, 12V Total number of batteries = (3.9) Total number of batteries = 3.3.4 Sizing of the Charge Controller The MPPT Solar regulator is designed according to the output current rating required to the battery. We know we have 1800W of panels (independent of the configuration) and from the design we are using a 48V battery bank. Then MPPT. (3.10) If we choose a 24V system, this would regulate 1800W/24 = 75A MPPT. The lost power of a 75A MPPT is double the current of a 40A MPPT, yet another reason to work with a higher battery voltage. 3.4 The breakdown of the Solar Power Installation The Complete Solar Power System is thus: 1 x 48V 3kW Inverter system 6 x 300W Solar Panels 8 x 200A.h deep cycle batteries 1 x 45A PWM Regulator. Figure 3.2: The 1500W Installation Circuit Diagram The fig. 3.2 shows the typical layout of the 1500W hybrid solar power system that consist of new layout of sockets for the twelve (12) units of computer systems and system unit, 30A solar charge controller, 600V/100A change over, two units of 100AH/12V connected in series, 1500W inverter system, two (2) units of solar panel connected in parallel. Plate 3.1: Pictorial overview of the 1500W installation CHAPTER FOUR TEST AND RESULTS 4.1 TEST ANALYSIS AND DISCUSSION The following tests were carried out during The installation During loading When on no-load. 4.1.1 Solar Panel Testing There are two things that needs to be measured in order to ensure the panel is functioning properly. Manufacturers open circuit voltage: 39.3V Open circuit voltage: 34.6V Short circuit current: 2.0A Manufacturer’s short circuit current rating: 9.38A To measure open circuit voltage, the panel can or cannot be in sunlight but care must be taken since the panel will be live when it is in sunlight and there is possibility of electric shock. The reading was taken using multimeter. The readings (open circuit voltage and short circuit current) should be compared with the rating of put in place by the manufacturers. The reading gotten also depends on the sun intensity as of the time the reading was taken. 4.1.2 Charge Controller Testing A visual inspection testing was conducted to check how the voltage going to the battery was regulated at full charge. The calculated battery voltage was = 13.2V × 2 The total battery voltage = 26.4V The charge controller voltage display was 27.2V at full charge. This value 27.2V was the practical value. 4.1.3 Battery Testing Without a functioning charge controller, it will not be completely certain to determine the battery’s capability to hold a charge. A visual inspection was carried out to determine the healthy condition of the battery. Things to look out for include: Leaking acid Crystallization on the terminals Physical damage like cracks on the battery. The battery was connected in both series and parallel and their respective voltage and current was obtained. Battery rating = 12V/100AH Total number of batteries = 2 Series connection: Voltage = 24 volts Current = 100amp. Parallel connection: Voltage = 12 volts Current = 200amp 4.2 System Design Testing (under no-load): Here is the specifications for the installation 1×1500W inverter system 2×280 watts solar panel 2×12V/100AH battery 1×30A charge controller Under no-load the 24V battery was carefully connected to the 1500W inverter and these readings was taken down. The voltage was tested and it reads 230V The frequency meter reads 50Hz The battery voltage reads 27.2V 4.3 System Design Test (on-load test) This test was conducted by connecting loads to the inverter individually and removing them before putting in another load and also another test was conducted by connecting all the loads incrementally without removing them until the inverter reaches its tripping point. Table 4.1: The table of load versus watts consumption when loads are connected individually LOAD WATTS CONSUMPTION(W) Computer system 1 72 Computer system 2 72 Computer system 3 57 Computer system 4 86 Computer system 5 72 Computer system 6 72 Computer system 7 86 Computer system 8 72 Computer system 9 57 Computer system 10 72 TOTAL WATTS = 718W Table 4.2: The table of load versus watts consumption when the loads are all connected incrementally. Number of computer systems WATTS CONSUMPTION(W) 1 72 2 129 3 250 4 302 5 337 6 361 7 417 8 457 9 526 10 590 Standing Fan 761 The total watts consumed by the loads = 761W 4.4 The rate of discharge of the battery on full load During the discharge of the battery, the solar panel was disconnected from the solar charge controller to avoid charging and discharging the battery by the applied loads and reading was taken at an interval of 20minutes. The battery voltage before discharge was 27.2V. Table 4.3: The rate of discharge of the battery Time(min) Terminal Voltage(V) 20 26.4 40 25.5 60 24.7 80 23.9 100 23.1 120 22.2 Figure 4.1: Graph of Rate of Discharge of Battery 4.5 The rate of charge of the battery During the charging of the battery, the solar panel was connected back to the solar charge controller to enable the solar panel charge the battery and reading was taken at an interval of one hour (1hr). The battery voltage before charging was 22.2V. Although the intensity of the sun was low during this charging period. Table 4.4: The charging rate of the battery Time(hour) Terminal Voltage(v) 1 23.2 2 24.1 3 25.4 4 26.7 5 27.2 Figure 4.2: Graph of Rate of Charge of Battery Table 4.5: Bill of Engineering Measurement and Evaluation (BEME) Item Quantity Unit price (#) Cost (#) Monocrystalline Solar panel 2 70,000 140,000 12V/100AH Deep cycle Battery 2 55,000 110,000 Charge controller 1 25,000 25,000 1500W Inverter 1 60,000 60,000 6”×3” Patress box 13 150 1950 Trunk box 12 length 250 3000 2 in 1 13A Sockets 13 500 6500 11/2 inch concrete nail 1 pkt 350 350 2.5mm2 cable 1 coil 11,500 11,500 I00A Change over 1 1,800 1,800 Silicon Gum/glue 1 700 700 Insulation tape 3 100 300 Engraving of names on the equipment’s 1,500 1,500 Hack saw with blade 1 1500 1500 Board with nails 300 300 Board for hanging inverter 1 700 700 Concrete nail and screw 300 300 13A plug 1 300 300 Leasing of Ladder 1,000 20 yards of 10mm2 wire 2 10,000 20,000 15A socket 1 300 300 Workmanship 10,000 Transportation 1,000 Miscellaneous 10,000 Total #408,000 CHAPTER FIVE CONCLUSION AND FUTURE WORK The Solar/mains power supply system can provide an uninterrupted power for a residential building. All the power the system needs will be generated by a solar panel that will store its charge with a sealed deep cycle battery. 5.1 CONCLUSION The proposed 3KVA Hybrid powered supply for ICT laboratory is an attempt to explore the possible changes that can be made to adverse environmental effects of fossil power and the dangers carbon from generators. A developing country like Nigeria where the power generated presently is insufficient and sunlight is usually abundant, represents one of the biggest potentials of solar power generation. Solar power could be generated all year round but it works best when the sun is at its maximum. Solar powered uninterruptible power system can be optimally used during the dry season when water level in the dams are low for sufficient hydro power generation and there's high availability of solar radiation due to high sunshine hours compared with other season, that are favorable for hydro power generation. Moreover, given both the immediate and long-term harmful effects of power generation through burning of fossil fuels and the dangers of nuclear power to reduce the over dependence on hydropower, the abundant of sunlight is the best answer. With independent break-through that advance technology combined with governmental and industrial cooperation, solar power is poised to take an ever-expanding role in power generation. With regards to high evaporation, nuclear waste and the effects of fossil fuel on the environment caused by conventional ways of power generation, we hope that the time when solar power will become more widely used than conventional power is not far away. We need a solar future if we are to live in a powerful and intact environment. Finally, considering the availability of solar energy in Nigeria, present technologies for the conversion of this energy into power and the economies of the power generated, the generation of power from solar energy in Nigeria is viable. 5.2 RECOMENDATION The design of this project was successful. However, there are certain factors that limit the proposed 3KVA solar power system plan which is insufficient funds. The inverter used in this project is of smaller rating (1500Watts) compared to the proposed 3KVA inverter system and this means that it has great limitations to the loads it can carry. The battery and solar panel should also be increased for better performance and a solar panel of about 300 watts would be a good choice. This is because an inverter with a higher power requirement will simply demand a higher current from the circuit. Also a bigger battery with a higher ampere hour factor should be used for future design. This will go a long way to boost the overall current in the circuit. REFERENCES [1] A. G. Bin Mat Husin (Universiti Teknologi Malaysia, 2009) [2] Typical Solar Powered System https://blurts.me/solar-panels-wiring-diagram-installation.html/solar-energy-in-pakistan-basic-architecture-of-power-and-panels-wiring-diagram-installation/. Last retrieved 6th July 2018 [3] Residential Solar Power System https://www.cleanenergyauthority.com/solarenergyresources/3typesofresidentialsolarelectricpowersystems. Last retrieved 6th July 2018 [4] Solar Charge Controller, www.energy.wsu.edu/Documents/SolarPVforBuildersOct2009.pdf [5] Guide-Comparing-PWM-MPPT-Charge-Controllers https://www.phocos.com/wp-content/uploads/2015/12/Guide-Comparing-PWM-MPPT-Charge-Controllers.pdf. Last retrieved 6th July 2018 [6] PWM Solar charge controller http://store3.sure-electronics.com/dc-te11157. Last retrieved 6th July 2018 [7] MPPT solar charge controller https://www.wattuneed.com/en/mppt-regulator/4797-regulator-mppt-srne-48v-60a-0712971136731.html. Last retrieved 6th July, 2018 [8] solar-panels http://www.qrg.northwestern.edu/projects/vss/docs/power/1-what-are-solar-panels.html. Last retrieved 6th July, 2018 [9] solar-panel diagram https://www.mrsolar.com/what-is-a-solar-panel/. Last retrieved 6th July 6, 2018 [10] Types of solar panel https://www.ecokarma.net/solar/types-of-solar-panels/. Last retrieved 6th July 6, 2018 [11] Monocrystalline-solar-panel http://www.poweracu.com/photovoltaic/monocrystalline-solar-panel-lg-neon2-lg315n1c-g4-neon-2-315wp.html. Last retrieved 6th July, 2018 [12] Polycrystalline solar panel http://energyinformative.org/best-solar-panel-monocrystalline-polycrystalline-thin-film/. Last retrieved 6th July, 2018 [13] P. Manimekalai, R. Harikumar, S. Raghavan, An Overview of Batteries for Photovoltaic (PV) Systems International Journal of Computer Applications (0975 – 8887) Volume 82 – No 12, November 2013. [14] Types of solar panel http://wikipedia.com/types-of-solar-inverter. Last retrieved 6th July, 2018 [15] G. van der Merwe, Photovoltaic Solar system calculator, http://www.solarpanel.co.za/solarpowercalculator.html, Last retrieved 14th July, 2018 [16] LTI Power Systems, Industrial Inverters 24 / 48 / 120VDC https://www.ltipowersystems.com/Catalog/Datasheet-1-10kva-Inverter.pdf, Last retrieved 16th July 2018