DESIGN AND BUILDING OF STAND ALONE 2KVA PV GENERATOR
A stand-alone power system is an off-the-grid electricity system for locations that are not fitted with an electricity distribution system. Typical stand-alone power system include one or more methods of electricity generation, energy storage, and regulation. Storage is typically implemented as a battery bank, but other solutions exist including fuel cells. Power drawn directly from the battery will be direct current extra low voltage (DC ELV), and this is used especially for lighting as well as for DC appliances. An inverter is used to generate AC low voltage, which more typical appliances can be used with. This stand-alone photovoltaic power system is independent of the utility grid and uses solar panels in conjunction with batteries.
TABLE OF CONTENT
TABLE OF CONTENT
DEFINITION OF TERMS
2.0 LITERATURE REVIEW
2.1 PHOTOVOLTAIC SOLAR SYSTEM
2.2 DIFFERENT TYPES OF SOLAR CELLS
2.3 PHOTOVOLTAIC SOLAR GENERATOR
3.0 PHOTOVOLTAIC SYSTEM SIZING
3.1 FACTORS AFFECTING PHOTOVOLTAIC SYSTEM SIZING
3.2 SIZING OF THE SOLAR ENERGY
3.3 SIZING OF THE BATTERY
3.4 SIZING OF THE VOLTAGE REGULATOR
3.5 SIZING OF THE INVERTER
4.0 CASE STUDY: AN OFFICE IN PURE AND APPLIED PHYSICS DEPARTMENT, LAUTECH, OGBOMOSO.
4.1 GEOGRAPHY LOCATION
4.2 OFFICE APPLIANCES
4.3 SIZING THE SOLAR ENERGY
4.4 SIZING OF THE BATTERY BANK
4.5 DISCHARGE DURATION
4.6 SIZING OF THE SYSTEM WIRING
4.7 SYSTEM COMPONENTS SUMMARY
The sun provides the energy to sustain life in our solar system. In one year, the earth receives enough energy from the sun to meet its energy needs for nearly a year. Photovoltaic is the direct conversion of sunlight to electricity, it is a beautiful alternative source of energy to conventional sources of electricity for many reasons it is safe, silent, non – polluting, renewable, highly modular in that their capacity can be increased incrementally to match with gradual load growth, it is reliable with minimal failure rates and projected service lifetimes of about 20 to 30 years. It requires no special training to operate, it contains no moving parts, it is extremely reliable and it’s virtually maintenance free, and can be installed almost anywhere.
A photovoltaic system is a complete set of interconnected components for converting sunlight into electricity by photovoltaic process including array, balance of system and load. The intensity of sunlight that reaches the earth varies with time of the day, season, location and the weather condition, the total energy on a daily or annual basis is called Irradiation and indicates the straight of sunshine. Irradiation is expressed in Whm – 2 per day or KWh.m-2 per day. Different geographical regions experience different weather patterns, so the site we live is a major factor that affects the photovoltaic system design, the orientation of the panels, finding the number of days of autonomy where the sun does not shine in the sky and choosing the best tilt angle of the solar panels.
Photovoltaic panels collect more energy, if they are installed on a tracker that follows the movement of the sun although it is an expensive process; for this process they are usually fixed in a particular position with an angle called the tilt angle B. This angle varies according to seasonal variation, for instance, in summer the solar panel must be more horizontal while in the winter, it is placed at a steeper angle.
In this project, the various components of a photovoltaic system and factors affecting its design for the purpose of domestic use is explained. Then a residence model with medium energy requirements in one of the offices in Pure and Applied Physics Department, Ladoke Akintola University of Technology, Ogbomoso is taken as a study case. The design procedures of the photovoltaic system will be provided in ascending manner.
1.1 SYSTEM DESCRIPTION
Photovoltaic system is considered of a variety of equipment in addition to the photovoltaic array, a balance of system that wired together to form the entire fully functional system capable of supplying electric power and these components are:
1. Photovoltaic Cells: Represent the fundamental power conversion units, they are made from semi – conductor materials and convert sunlight energy to electricity. Individual photovoltaic cells are usually quite small, producing around 1 to 2 watt of power. To increase the power output of a photovoltaic cells, they have to be connected together to form modules, modules are connected in parallel and series to form larger parts/units called Panels and Arrays to produce electric power that meets any electric need.
2. A storage Medium: Battery bank which is involved in the system to make the energy available at night or at days of autonomy (sometimes called dark days) when the sun is not providing enough radiation the standard batteries that are used in solar system are lead – acid batteries because of their high performance; long life and cost effectiveness.
3. A Voltage Regulator or Charge Controller: Is an essential part of nearly all power system that change batteries, the basic function of a controller is to block reverse current and prevent battery from getting overcharged. Some controllers also prevent battery over discharging, electrical overload, display battery status and the flow of power.
4. An Inverter: Is device that changes a low d.c voltage to usable a.c voltage. It is one of the solar energy. Systems main element is the solar panel generate d.c voltage. Inverters are different by the output wave format, output power and installation type. It is also called power conditioner because it changes the form of the electric power. There are two types of output wave format: Modified Sine wave (MSW) and Pure Sine wave (PSW). The MSW inverters are economical and efficient, while the pure sine wave inverters are now sophisticated with high end performance and can operate virtually any type of load. There are two types of inverters that can be installed, the stand alone installation and grid connection installation.
5. Balance of System such as protection devices that keep the system components safe during their operation including blocking diodes that protect the components from getting damaged by the flow back of electricity from the battery at night. Bypass diodes that are connected across several cells to limit the power dissipated in shaded cells by providing a low resistance path for the module current and lightning protection that includes devices to protect the sensitive electronic components from the high voltage transient and ground faults. Wiring is a mean, through which the components of a solar energy system are connected together; correct wire needs to be used to ensure low loss of energy and to prevent overheating and possible damage or even fire. Using correct wire size and types of wire will enhance the performance and reliability of the photovoltaic system. The size of the wire must be large enough to carry the maximum current expected without undue voltage loss.
6. A.C and D.C Loads: Are the appliances (such as lights and radio e.t.c) and the components (such as fridges, water pumps, washing machines e.t.c) which consume the power generated by the photovoltaic array.
The photovoltaic system has been classified according to how the system components are connected to other power sources such as stand alone (SA) and utility – interactive (UI) system. In a stand alone system, the system is designed to operate independent of the electric utility grid, and is generally designed and sized to supply certain d.c/a.c electrical loads. A bank of battery is used to store the energy in a form of d.c power that is produced by photovoltaic modules to be used at nights. The d.c output of the batteries can be used immediately to run certain low d.c voltage loads such as lighting bulbs or refrigerators or can be converted to a.c voltage to run a.c loads which constitute of most of the appliances.
The aim of this project is to install a 2KVA stand – alone photovoltaic system, using an office in physics department as a case study.
1. To generate electricity from solar energy in which the source is free in nature and abundant.
2. To find solution to irregularity in power supply by PHCN
3. To carry out the system sizing in solar power generator.
4. To study the performance of each component constituting the solar power generator.
1.4 Significant Study
In respect to failure of power supply and perpetual increase in fuel price to run power and most times fuel scarcity, there is need to introduce the use of solar energy power system towards a stable power supply for developing and developed nations of the world.
1.5 Definition of Terms
SUN – Source of energy
SOLAR PANEL – It’s device that converts light energy to electrical energy
SOLAR REGULATOR – It’s a device that regulates from 40VDC to 28VDC
BATTERY – It’s a device that serves as reservoirs/storage device
INVERTER – It’s a device that converts D.C (12v) [Battery/Solar] 28VDC to AC 220AC.
LOAD – AC output using devices (laptop, Bulb, Ceiling fan, Handset Charger)
POWER – Voltage × Current
WATTAGE – Power factor [0.8] × Power i.e. power (VA)
SOLAR CELLS – Is the smallest semiconductor (silicon) device that converts solar energy (sunlight) to electrical energy (DC)
ARRAY – Is the combination of panel in series or parallel
PANEL/MODULES – Is the combination of cell in series or parallel.
SHORT CIRCUIT – It has low resistance or no resistance and potential differences of zero.
CLOSED CIRCUIT – The current is generated across the load.
OPEN CIRCUIT – It has no current to generate across the with high resistances.