CHAPTER ONE

INTRODUCTION

1.1       BACKGROUND OF STUDY

Photovoltaic (PV) offers consumers the ability to generate electricity in a clean, quiet and reliable ways: photovoltaic system comprises of photovoltaic cells device that convert light energy directly into electricity, because the source of light is usually sun. They are often called solar cells. Solar power is the energy from the sun. “Solar” is a Latin word from sun. Solar energy is considered a serious source of energy for many years because of the vast amount of energy that is made freely available [Perlin, 1999]. The word photovoltaic comes from photo meaning light and voltaic which refers to producing electricity. Therefore the photovoltaic process is reducing electricity directly from the sunlight. Photovoltaic (PV) cells convert sunlight directly into electricity without creating any air, land or water pollution. Solar power is a clean renewable resources with zero emission and has got tremendous potential of energy which can be harnessed using photovoltaic cells. With recent development, solar energy is available for industrial and domestic use with the added advantage of minimum maintenance. Solar energy could be made financially viable with government tax incentives and rebates [Daniel, 1991]. Most of the developed countries are switching over to solar energy as one of prime renewable energy source. The current architectural design makes provision for photovoltaic cell.

Photovoltaic (PV) cells convert sunlight directly into electricity without creating any air or water pollution. Modules are combined to create solar arrays. An array is a group of modules assembled together and designed to meet a certain electrical load. Most arrays can be mounted on the rooftops of homes and are designed to generate a certain amount of electricity over the course of a year. Generally solar modules convert about 10-15% of the energy that strikes them into electricity. This means that for every 100 units of energy that actually hit the panel, only 15 of them actually enter the home as electricity (Goswami, 2005). This is the biggest area of research now, as scientists recognize that significant advancements in solar efficiency will lead to cheaper solar energy.

Solar (PV) Panels generate direct current (DC) electricity, but most applications in our homes require AC. This means however, that the electricity coming out of the solar array must be converted to AC application. This is achieve with an inverter, which takes the DC power and makes AC power. Some devices (certain lights, batteries, special devices) use DC power and therefore do not need an inverter.

Recently, there have been several renewable energy project in many countries which shows that renewable energy can directly contribute to poverty alleviation by providing a substantial amount of energy needed for creating business and employment especially in rural communities [FME, 2013]. To increase the utility, dozens of individual photovoltaic (PV) cell are instrumented together in a seal, weather proof packaged called module. When two module are wired together in series, their voltage is doubled while their current stays constant. When two module are wired in parallel, their current is doubled voltage is constant.

A grid connected PV system will require a utility interactive DC to AC converter with the help of an inverter. This device which converts the DC electricity produced by the PV arrays into AC typically require for domestic load such as radio, television lightening, refrigerator fans etc. requires a storage facility i.e. battery is used to store electricity from the PV’s for use when there is no sun; any number of module can be connected together to give, the desired electrical output and as recommended.

The major obstacle to faster development of solar energy production was and still is cost of equipment. This at last is rapidly decreasing, with increased efficiency and better standard that are in use in the solar system today. It does not add to the “greenhouse effect” gasses and global warming. The best of all, after installation costs, it is absolutely free, with minimum close to zero maintenance requirement.

1.2MOTIVATION

In an era of high energy price, the necessity for an alternative source of energy for the department and the need to educate the public to do the same cannot be over emphasized. The objective of this project is to implement an alternative power based on renewable, clean and cheap sources to augment the existing electricity from the national grid.

Thus, the project is to carry out maintenance and upgrade work on solar power system supplying some Laboratories and Offices in the Electrical/Electronic Engineering Department (EEED). The department offers course specific to Solar Energy Technology (SET 438). This upgrade and maintenance work is to create opportunities for students to relate the classroom lectures to the practical installation by physical participation of each student. It will also create numerous learning opportunities for self-development.

1.3       STATEMENT OF PROBLEM

From the result of the survey carried out on the previous installation of alternative power source (Solar) in the department, the power was only limited to Power and Control lab, excluding some offices and stores. In addition a low rated charge controller 24V, 50A was used which does not suit the system designs and operating voltage. Sub-standard cables were also observed to have been used which does not comply with IEEE Regulations. The solar panel were not connected according to the system voltage i.e. 48V.The panels were dusty thereby reducing the PV output which in turn reduce the output and performance of the system. The tilting angle of the panels was not properly adjusted to 450. The inverter cooling fan was found to be bad thereby generating excess heat in the inverter unit .The connected labs and offices are not protected with Miniature circuit breaker (MCB) against overload. Lastly, there was no means of isolation of the input source to the inverter. Thus, calling for the needed upgrade of the system.

In this current project work, the upgrading and maintenance work comprises of the extension of power to other labs, offices, stores and the upgrading of solar charge controller. The solar panels will be cleaned to free them from dust, tilting angle will be corrected and a means of over load protection and isolation will be incorporated into the system.

1.4       AIMS AND OBJECTIVES

The aim of this project is to maintain and upgrade the solar power system in EEED towards providing alternative power source during working/lecture hours when there is an outage from the national grid. The objectives are therefore as follows;

1.      To carry out survey on the existing installation to find the actual load demand.

2.      To carry out maintenance work on the existing solar power installation.

3.      To upgrade the existing solar system installation based on the data collected from the condition survey.

1.5       SCOPE OF STUDY

This project is to provide alternative power supply to specific load in laboratories, offices and stores in EEED. Nine (9) PV panels, one charge controller, an inverter of 5.5KVA, four 12V, 150A/H batteries and cables is used to power the labs, offices and stores. However, due to limited finances the number of batteries to be purchased is limited to 2 and are to power 30 lighting points and 15 sockets.

1.6       METHODOLOGY

The block diagram of the inverter system is as shown in Fig 1.1. It consist of six sub unit visa-viz.

Fig 1.1: Block Diagram of Installation of 5.5kva Inverter

i.                    Photovoltaic (PV) Array: This is connection of modules in series/parallel in order to achieve the desired voltage and current.

ii.                  Solar Charge Controller (S.C.C): This receives the output of the Photo Voltaic (PV) array as input in order to control the output voltage and current produced by the array and input to the battery for charging.

iii.                Battery Unit: This is a secondary cell unit, capable of storing enough DC voltage from either the sun or AC supply mains, of which if there is any failure from main supply it convert the battery voltage to AC voltage.

iv.                Inverter Unit: This single unit converts D.C voltage into A.C voltage with the help of the inverter unit.

v.                  Utility Gird: This is the supply from national grid which serves as another source of power apart from the solar (sun).

vi.                Load Output Unit: This is the final output from the inverter which produces 320VAC and also serves as another Alternative that powers the load selected.

The procedure adopted for this project is based on the block diagram of Fig 1.1

1.7   REPORT OUTLINE

This project consists of five chapters in  which chapter one shows the Introduction, Chapter two gives the literature review, chapter three gives the installation of the system of designed methodology, chapter four present the construction, chapter five is testing and result and finally Chapter six present the conclusion and recommendation

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