Economics Analysis Of Hybrid PV/Diesel Power System For Residential Loads

ABSTRACT

 This thesis is a study on integration of photovoltaic generators into an existing diesel- unreliable grid connected system. The main goal of implementing PV-diesel hybrid system is to reduce diesel consumption and the import of fossil fuel used in electricity power supply. Before designing the system, it is necessary to create a load profile for 120 households and pre-design the size of the PV generator, the capacity of storage system and inverter type/size selection. The load profile data is based on the average of monthly energy consumption gathered from village households.

Detailed simulations and financial analysis are performed with HOMER to compare different systems and their viability. The simulations include four different designs starting from the existing system, diesel generator with unreliable grid, followed by PV generator and unreliable grid, PV and diesel generator and ended with the complete hybrid system. Once the Hybrid system is determined a detailed design is done to optimize the lowest cost PV-diesel hybrid system. The final simulated PV-diesel hybrid system is suggested with a PV capacity of 270 kWp, existing diesel capacity with 200 kVA, an inverter output of 115 kW and battery bank nominal capacity is 1872 kWh. The system renewable fraction is 53% and the project life cycle is 25 years. The PV-diesel hybrid system is projected to produce electricity at a cost of 45 naira/kWh. This cost is significantly lower than the 46 naira/kWh paid to the diesel operator, as well as lower than 43 naira/kWh paid to the utility grid.In addition, and according to the given information from the owner, an estimated diesel consumption of 104000 ltr/year, the simulation result shows diesel consumption at 40000 ltr/year. The reduced carbon dioxide production by 65%, from 776 to 272 tons per year, provides further justification for the PV installation in a commercial PV-diesel hybrid system.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

TABLE OF CONTENT

NOMENCLETURE

CHAPTER ONE

INTRODUCTION

1.1      BACKGROUND OF THE STUDY

• AIM OF THE STUDY
• SCOPE OF THE STUDY
• LIMITATION/PROBLEM OF THE PROJECT
• METHOD USED

CHAPTER TWO

LITERATURE REVIEW

• REVIEW OF PREVIOUS WORK

CHAPTER THREE

• METHOD/MODELLING
• SYSTEM BLOCK
• PRE-DESIGN PREPARATION
• PROFILE LOAD ESTIMATION
• PV ARRAY SIZE AND BATTERY CALCULATION
• SYSTEM DESIGN AND SIMULATION
• SYSTEM INSTALLATION
• DETAILED SYSTEM DESIGN
• HOMER DESCRIPTION
• UNRELIABLE GRID MODELLING
• SIMULATION SYSTEMS
• DIESEL GENERATOR AND GRID SYSTEM

CHAPTER FOUR

4.0      RESULTS

• DIESEL GENERATOR AND GRID SYSTEM SIMULATION
• PV GENERATOR AND GRID SYSTEM SIMULATION
• PV-DIESEL GENERATOR SYSTEM SIMULATION
• PV-DIESEL HYBRID GRID CONNECTED SYSTEM
• FINANCIAL ANALYSIS RESULTS
• SYSTEM SIMULATION AND SENSITIVITY ANALYSIS
• HYBRID PV DIESEL UNRELIABLE GRID SYSTEM ANALYSIS

CHAPTER FIVE

• DISCUSSION AND CONCLUSIONS
• REFERENCES

Nomenclature

CHAPTER ONE

1.1                                                     INTRODUCTION

The growing concerns of global warming and depleting oil/gas reserves have made it inevitable to seek energy from renewable energy resources. Many nations are embarking on introduction of clean/renewable solar energy for displacement of oil-produced energy. Moreover, solar photovoltaic (PV)–diesel hybrid power generation system technology is an emerging energy option since it promises great deal of challenges and opportunities for developed and developing countries. Countries like Nigeria being enriched with higher level of solar radiation, is a prospective candidate for deployment of solar PV systems. Solar energy was invented because of energy shortage.

The impact of the energy shortage and the political instability led to the increased use of diesel generators that covered a 4 million population area of 10452 km 2. These diesel generators have to cover the electricity shortage when the main grid is down.

Daily electricity shortage is a common problem all around Nigeria, there is an outage rotation of eight to sixteen hours of blackout in the village daytime. Due to outage rotation, consumers have to pay two different bills every month, the consumption price from the grid is around 4680 naira /kWh, and from the diesel generator is about 1000 naira/kWh. (MEDSOLAR, 2015)

The country is located on the Mediterranean Sea between northern latitudes 33°03′ and 34°41′ and eastern longitudes 35°06′ and 36°37′, Khiam village is located at latitude 33°19′ north and longitude 35°36′ east at 697 m above sea level. The country’s location has an average annual solar radiation of 2200 kWh/m2. This solar energy potential, the track of the sun and the nature of the geographical site, are significant enough to implement renewable photovoltaic (PV) energy in the region. One factor which increases the attractiveness of PV as a renewable energy solution in Nigeria, is the government heavily relies on fossil-fuel and natural gas imports from neighbouring countries. The high dependency on diesel generators to compensate the electricity shortages is the reason behind the government’s decision to increase the renewable share from 3% to 12% at 2020.

1.2                                                AIMS OF THE STUDY

The aim of this thesis is to examine the feasibility of implementing PV systems in an existing unreliable hybrid diesel mini-grid system in a village in Nigeria.

The aim of PV implementation is to reduce the consumption of diesel fuel, the working hours of diesel generators, as well as the domestic electricity bills. The optimal system design will be achieved through the pre-design preparation and system design simulation.

Another aim of this thesis is to evaluate the economic feasibility of a PV-diesel hybrid system over a 25 years lifetime compared to a diesel grid unreliable system.

1.3                                               SCOPE OF THE STUDY

Literature indicates that commercial/residential buildings in Nigeria consume about 10–45% of the total electric energy generated. The aim of this study is to analyze long-term solar radiation data of Nigeria to assess the techno-economic feasibility of utilizing hybrid PV–diesel power systems to meet the load of a typical residential building (with annual electrical energy demand of 35,120 kWh). The monthly average daily solar global radiation ranges from 3.61 to 7.96 kwh/m². National Renewable Energy Laboratory’s (NREL) Hybrid Optimization Model for Electric Renewable (HOMER) software has been employed to carry out the present study.

1.4                               PROBLEM/LIMITATION OF THE STUDY

The integration of PV-diesel hybrid system is purely theoretical and HOMER software tool will be used. The component selection of charge controller and inverter was limited from HOMER to a combi/inverter.

Solar equipment selected in the system, like charge controller and inverter, are imported from China. The price for these components is configured according to the Chinese market price. The electricity consumption input bills to create the village load profile was gathered from different households supplied by diesel generator and the unreliable grid. The diesel generator selected from the village is rated to 200 kVA.

1.5                                                            METHOD USED

The following steps should be used to achieve the aims of this thesis work:

1. Literature review regarding the implementing of PV to an existing diesel
2. Pre-design preparation:
   • Creation of load profiles based on information from household energy
   • Creation of village annual load based on household monthly energy consumption c- Estimation of load profile PV area and battery storage
3. System design and simulation in HOMER software tool:

a- PV system design needs collection of all necessary data from NASA resources. b- A grid modeling in HOMER configured with the actual electricity price.

• Battery size to supply the load and reduce diesel generator operation
• Adding converter from HOMER component database to convert DC/AC e- Information on existing diesel generator included in the system design.

f-         Different system HOMER configuration and simulation.

4. Analysis of simulation results and comparison of the cost of energy (COE) with the actual cost of electricity. Conclusions regarding the feasibility of the
5. Analysis of results and preparation of recommendation for the use of the system