CHAPTER ONE

1.0     INTRODUCTION

1.1     BACKGROUND OF THE STUDY

Electricity is a form of energy that comes in positive and negative forms, that occur naturally (as lighting), or is produced (as in generator). It is a form of energy, which we use to power machines and electrical devices. When the charges are not moving, electricity is called static electricity. When the charges are not moving they are an electric current, sometimes called “dynamic electricity”.

Electricity is created through the friction between two materials for instance a wool cap and a plastic ruler. This may make a spark (Merriam, 2016). Solar inverter, or photovoltaic (pv) inverter, convents that 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, of grid electrical network.

It is a critical balance of system (BOS) component in a photovoltaic system, allowing the use of ordinary al-power equipment solar power inverter have special functions adapted for use with photovoltaic arrays, including Maximum Power Point Tracking (M.P.P.T) and anti- islanding protection (Lewis, 2010).

David prince coined the termed inverter. It is unlikely that any living person and now establish with certainly that prince or any one else was the originator of the commonly used engineering term. However, in 1925 Prince did published an article in the G.E Review (vol. 28, no. 10, P. 676-81) cited “the inverter”. This article contains nearly all important element required by modern inverters and is the earliest literature. Prince explained that an inverter is used to convert direct current into single or polyphase alternating current (David, 1925).

An inverter is a device which converts a D.C (Direct current) voltage source into an AC (Alternating Current) voltage source. It is useful when you want to run an appliance designed to be operated from AC mains 120 or 240 Vac, 50 or 60 H2) from a battery (often 12 or 24 Vdc). Typical application maybe when you are off grid with solar panel and storage battery, when you want to operate main appliances like TV, Fan, Desktop Computers and Refrigerator. They are also used for backup power for critical load mains power fails.

1.2       STATEMENT OF THE PROBLEM

As a result of unavailability of electricity supply, many appliances especially in the departmental computer room are being interrupted. These problems have been in existence for a very long time thereby causing drawback to the student’s practicals.

This project is to provide a backup power by installing a solar inverter and a deep cycle rechargeable battery to make them function and useful to the student and the department as a whole because constant supply of power is needed in the department.

1.3     AIMS AND OBJECTIVES

The aim of this project is to install a solar inverter and a deep cycle rechargeable batteries for powering (30) thirty desktop computers and a projector in the computer room.

1.4     OBJECTIVES

•         To determine the total energy demand of the computer room, department of Agric & Bio-Environmental Engineering Kaduna Polytechnic.

•         To carryout market survey.

•         To purchase the (B.O.S) equipments

•         To construct a metal rack for supporting the inverter/batteries.

•         To test the performance of the install (B.O.S) equipment.

1.5     SIGNIFICANCE OF THE STUDY

This installation of solar inverter in Agric & Bio-Environmental Engineering department will provide a supplementary alternative means of electrical power needed to operate the computer room effectively.

1.6     SCOPE AND LIMITATION

This project is limited to the installation of solar inverter and a deep cycle rechargeable battery for powering thirty desktop computers and a projector.

CHAPTER TWO

2.0     LITERATURE REVIEW

According to IAU (2006), the solar system is the gravitationally bound system of the planets and the sun plus other object that orbit it, either directly or indirectly.

By this definition, the solar system has eighth planets: mercury, Venus, earth, mars, Jupiter, Saturn, Uranus, and Neptune. The solar system is a power system designed to supply usable solar power by use of photovoltaic’s. It consist of an arrangement of several components, including solar panel to absorb and convert sunlight into electricity, a solar inverter to change the electric current from DC to AC, as well as mounting, cabling, and other electrical accessories to setup a working system (International Energy Agency, 2011).

According to Ullan of (2015), solar panel absorb sunlight as a source of energy to generate electricity. A single solar module can produce only a limited amount of power; most installation consists of multiple modules. An inverter, a battery pack for storage, interconnection wiring, and operationally a solar tracking mechanism.

Solar energy is radiates light and heat from the sun that is harnessed using a range of ever evolving technologies such as solar heating, photovoltaic’s, solar thermal energy, solar architecture, molten salt power plants and artificial photosynthesis (Fraunhofer, 2014).

According to Morgan (2012), the most common application of solar has continued to fall so that in many countries it is cheaper than ordinary fossil fuel electricity from the electricity grid, a phenomenon known as grid parity. A solar inverter as 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 network.

According to David (1925) prince explained that an inverter is used to convert direct current into single or poly phase alternating current the article explains how the author took the rectifier circuit and the inverter, turning a direct current at one end and drawing out an alternating current at the other. An inverter is an electronic device that changes direct current DC to Alternating molecule cloud. An inverter can be entirely electronic or maybe combination of mechanical effect (such as a rotating apparatus) and electronic circuitry. (IEEE, 2000).

2.1     INVERTER

David prince probably coined the term inverter. It is unlikely that any living person can now, establish with certainly that prince (or anyone else) was the originator of the commonly used engineering term. However, in 1925 prince did publish an article in the GE review titled “the inverter”. (David, 1925). In 1925, prince defined “inverter” as the inverse of rectifier. In so doing, he demanded upon his audience having a clear a mental abstraction of rectifier for more two decades to 1925. It was understood to mean any stationery apparatus or rotating commentator for transforming alternating into direct current.

An inverter is an electronic device that changes direct current (DC) to alternating current (AC), and it is widely use when you want to run an appliances designed to be operated from AC mains (120 or 240 Vac, 50 or 60 H2) from a battery (often 12 or 24 Vdc). Typically application maybe when you are off grid with solar panel and storage battery. When you want to operate •mains appliances like TV, Fan, Desktop Computer and a Refrigerator, they are also useful for backup power for criteria load and mains power fails (IEEE, 2000).

2.2     CLASSIFICATION OF INVERTER

•         Stand-Alone Inverter: use in isolated system where the inverter draws the (DC) energy from batteries charged By photovoltaic arrays. Many stand-alone inverters also incorporate integral battery chargers to replenish the battery from (AC) sources, 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.

•         Grid-Tie Inverters: which match phase with a utility supplied sine wave. Grid – tie inverters are designed to shutdown automatically upon loss of utility supply, for safety reasons. They do not provide backup power during utility outages.

•         Battery Backup Inverters: they are special inverter which are designed to draw energy from a battery, manage the battery charge via an on broad charger, and export excess energy to the utility grid. These inverter are capable of supplying (AC) energy to selected loads during a utility outage, and are required to have anti-islanding protection

2.3     INPUT AND OUTPUT VOLTAGE OF AN INVERTER
2.3.1 INPUT VOLTAGE OF AN INVERTER

A typical power inverter device or circuit requires a relatively stable power demand of the system. The input voltage depends on the design and purpose of the inverter. Examples includes;

•         12v (DC), for smaller consumers and commercial inverter that typical run from a rechargeable 1 2v lead acid battery or automotive electrical outlet.

•         24,36 and 48v (DC), which are commonly standard from home energy system.

•         200 to 400 VDC , when power is from electrical vehicle battery packs in a vehicle to grid system.

•         Hundreds of thousands of volts, where the inverter is pat of a high voltage direct current power transmission system.

2.3.2  OUTPUT VOLTAGE OF AN INVERTER

The (AC) output voltage of a power inverter is often regulated to be the same as the grid line voltage, typically 120 or 240 Vac to the distribution level, even when there are changed in the load that the inverter to power numerous device designed for standard line power. Some inverters also allow selectable or continuously variable output voltage.

2.4     TYPES OF INVERTER

•         Square Wave Inverter: A square wave inverter is one of the simplest inverter types, which convert a straight (DC) signal to the phase shifting (AC) signal but the output is not pure (AC) i.e, in the form of a pure sine wave, but it is a square wave, at the same time they are cheaper as well, the simplest construction of the square wave inverter can be achieved by using an off switch before the typical voltage amplifying circuitry like that of a transformer.

•         Modified Sine Wave Inverter Or Quasi Sine Wave Inverter:               The construction of this type of inverter is a bit more complex than the simple square wave inverter, but still simpler than a pure sine wave inverter

•         A pure sine wave inverter: The electrical circuit of a pure sine wave inverter is more complex than a sine wave or modified sine wave inverter. Another way to obtain a square wave output from a square wave inverter and then modified this output to achieve a pure wave. Apure sine wave inverter has several advantages over its previous two forms.

•         More efficiency hence consumes less power

•         They can be adjusted according to your personal power requirement, since several types are available with different power outputs.

•         The output of a pure sine wave inverter is very reliable, but at the same time, there is a trade off between the price and reliability.

•         Due to this reasons they are the best option for sensitive equipment.

2.5     COMPONENTS OF AN INVERTER

•         Microcontroller: This is the main and integral part of an inverter. the main working of a microcontroller is to control the switching of signals according to the requirements. A single microcontroller can perform multiple functions (e.g) generating P.W.M for switching, controlling the protecting system e.t.c. there are various type and families of microcontrollers available in the market, for example: PIC microcontroller, 80 microcontroller can be used.

•         Bipolar Junction Transistor (BJTs): BJT or a bipolar transistor is a three layered device which is capable of controlling the current flow. In a BJT, a small current at the input of the device can control larger current at the output thus, BJTs can amplify currents. They can be used as a relay driver, as a switch, as a constant current source, as an amplifier (e.t.c)

•         H-Bridge: H - bridge is a topology in which four switching device BJTs, MOFSETs or IGBTs are intergrated together in a single circuit, the name H-bridge is given to it because of the typical arrangement of this circuit. Mainly used switching devices in H-bridge circuits are BJTs, Mosfets or IGBT.

•         Mosfets: The metal oxide semiconductor field effect transistor (MOSFET) is a voltage controlled device and requires a very small
input current. It is mainly used for switching of electronic signals as its switching speed is very high. It is the most commonly used FET in low-power high-frequency circuits, the mofsets is composed of a channel of n-type or p-type semiconductor material, and is accordingly called an           n-mosfet or a p-mosfet.

•          The depletion type mosfet (Dmosfet)

•          Enhancement type mosfet (E-mosfet)

•         Filters: At times it is desirable to have circuits capable of selectively filtering one frequency or range of frequencies out of a mix of different frequencies in circuit. A circuit designed to perform this frequency is called a filter circuit.

2.6     BATTERIES
The runtime of an inverter powered by batteries is dependent on the battery power and the amount of power being drawn from the inverter at a given time. As the amount of equipment using the inverter increases, the runtime will decrease.

In order to prolong the runtime of an inverter, additional batteries can be added to the inverter. When attempting to add more batteries to an inverter there are two basic options for installation.

2.6.1  Series Configuration

If the goal is to increase the overall voltage of the inverter, one can chain batteries in a series configuration. In a series configuration, if a single battery dies, the other batteries will not be able to power the load.

2.6.2 Parallel Configuration

If the soil is to increase capacity and prolong the runtirne of the inverter, batteries can be connected in parallel. This increases the overall ampere hour (Ah) rating of the battery set.

If a single battery is discharged though, the other batteries will then discharge through it. This can leads to rapid discharge of the entire pack, or even an over-current and possible fire. To avoid he large paralleled batteries may be connected via diodes or intelligent monitoring with automatic switching to isolate an under-voltage battery for the others.

2.7     SOLAR CABLE

A solar cable is the interconnection cable sued in photovoltaic power generation. Solar cables interconnect solar panels and other electrical components of a photovoltaic system. Solar cables are designed to be UV resistant and weather resistant they can.. be used within a large temperature range and are generally laid outside.

2.7.1  DC Connection

Individual modules are connected using cables to form the photovoltaic (PV) generator. The module cables are connected into a string which leads into the generator junction box, and a main (DC) cable connects the generator junction box to the inverter. In order to eliminate the risk of ground faults and short circuits the positive and negative cables, each with double insulation are laid separately.

2.7.2 Types of Cable

•         Coaxial Cable: Used for radio frequency signals or example in cable television distribution systems.

•         Direct-buried cable

•         Flexible cables

•         Hybrid Cables: can be used in wireless outdoor fiber-to-the antenna (FTTA) applications. In these cables, the optional fibers carry information and the electrical conductors are used to transmit power. These cables can b. placed in several environments to serve antenna mounted on poles, rowers or other structures.

You either get what you want or your money back. T&C Apply

Talk to us right now: (+234)906-451-7926 (Call/WhatsApp)

---