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i ENG470 Engineering Honours Thesis Feasibility Study of Microgrid Application for Murdoch University Alia Abdul Rahim Bachelor of Engineering Honours (Honours) Instrumentation and Control Engineering (Honours) (Major) Renewable Energy Engineering (Honours) (Minor) Supervisor: Dr Martina Calais Submission Date: 2 July 2019
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Page 1: ENG470 Engineering Honours Thesis - Murdoch University · i ENG470 Engineering Honours Thesis Feasibility Study of Microgrid Application for Murdoch University Alia Abdul Rahim Bachelor

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ENG470

Engineering Honours Thesis

Feasibility Study of Microgrid Application for Murdoch

University

Alia Abdul Rahim

Bachelor of Engineering Honours (Honours)

Instrumentation and Control Engineering (Honours) (Major)

Renewable Energy Engineering (Honours) (Minor)

Supervisor:

Dr Martina Calais

Submission Date:

2 July 2019

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AUTHOR’S DECLARATION

I, Alia Abdul Rahim, declare that this thesis is my account of my research and contains as its main

content work which has not previously been submitted for a degree at any tertiary education

institution. Additionally, references have been provided throughout this document where necessary.

Alia Abdul Rahim

02/07/2019

Date

Final Work Count (Body Text) = 12,108

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ABSTRACT

In this modern era, technology continues to develop and improve, experiencing a signification

transformation from the traditional concept and centralized power generation to an incorporated

system with distributed energy resources (DER) which is then located closer to the local loads. A

sustainable solution with this future concept would be the Microgrid application, and it is a growing

system in recent days. This system consists of an integration of the generation from different

renewable energy sources that contain energy storage systems. Microgrid also acts as a backup source

to failure of the main power supply allowing the network to operate independently. This technology

has provided a high reliance on the economy and the growing demand of the technologies such as the

energy generated from wind and solar. The growth in several Microgrid utilization has also decreased

the reliance on the usage of fossil fuels.

The idea of the Microgrid application and implementing it into the network of Murdoch University

would provide such significant benefits to the commercial ground. The objective of this thesis is to

analyse the opportunity of self-generation of electricity with the possibility of implementing

Photovoltaic systems, and a battery energy storage system. The demand for the electricity of the

campus would also be analysed with the university’s existing renewable energy source, which is the

diesel generator. MU has also experienced several events of power failure. Therefore, another aim of

the project is also to have these Microgrid components to act as a back-up source.

Risks from the failure of the main power supply will be identified in the introductory part of this thesis

before flowing into the concept of Microgrid. The design and the specifications of the components to

be integrated into the targeted network will be explained throughout the body of this chapter. The

output of the research will provide a summary of potential generation from the chosen components.

To have a self-generation of electricity would not only lead MU to be investing in the early stages but

would also lead MU to an amount of cost-saving upon the project lifetime.

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ACKNOWLEDGMENTS

I, first and foremost, would like to dedicate this thesis report to my family back in Malaysia. My

deepest gratitude and love towards them, especially my dearest parents, for sending me to Murdoch

University to pursue what I have become as a person now. Being the youngest, I am very lucky to have

four times the never-ending love and support from my brothers and sister.

I would like to thank Andrew Haning, my industrial supervisor, who had provided me with the

necessary guidance and supervision from the very start until the very end. To my thesis supervisor,

Dr. Martina Calais for her outstanding guidance and knowledge throughout the development of this

project. To James Woodford for assisting me in the early stages of this project. To Taskin Jamal for

sharing me his knowledge on HOMER software.

Also to Gary Higgins, Yuri Rivas and the rest of the Property Development Commercial Services Office

Team who have provided me with technical support, guidance and providing me with the essential

critical information in regards to the Substation 13 project.

Lastly to my immediate family and close friends, my deepest appreciation for being there for me since

the year of 2016 until the end of this journey. You have provided me with all the help that I needed.

Every person involved during my studies and the making of this thesis project, you have made this

possible.

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Table of Contents Author’s Declaration ............................................................................................................................... ii

Abstract .................................................................................................................................................. iii

Acknowledgments .................................................................................................................................. iv

1 Introduction .................................................................................................................................... 1

1.1 Project Background ................................................................................................................. 3

1.2 Project Objectives ................................................................................................................... 5

2 Literature Review ............................................................................................................................ 6

3 Preliminary Works ......................................................................................................................... 22

4 HelioScope .................................................................................................................................... 24

4.1 Module Selection .................................................................................................................. 25

4.2 PV System Design .................................................................................................................. 26

4.3 Revised Design Considering Shading .................................................................................... 29

5 Required Data ............................................................................................................................... 31

6 Microgrid Application ................................................................................................................... 33

6.1 Microgrid Flow ...................................................................................................................... 33

6.2 Photovoltaics ......................................................................................................................... 35

6.2.1 Sources of System Loss ................................................................................................. 38

6.2.2 Shaded and Non-Shaded PV Generation ...................................................................... 38

6.3 Diesel Generator ................................................................................................................... 41

6.4 Battery ................................................................................................................................... 42

6.4.1 Battery Size ................................................................................................................... 42

7 Results & Analysis ......................................................................................................................... 44

7.1 Microgrid Performance Analysis ........................................................................................... 44

7.1.1 Potential of Solar Generation ....................................................................................... 44

7.1.2 Potential of Solar and Battery Generation .................................................................... 46

7.1.3 Potential of Microgrid Generation ................................................................................ 47

7.2 Economic Analysis ................................................................................................................. 50

7.3 HOMER Analysis .................................................................................................................... 53

7.3.1 Battery, Solar and Inverter Only ................................................................................... 54

7.3.2 All Components ............................................................................................................. 55

8 Summary ....................................................................................................................................... 57

8.1 Future Works ........................................................................................................................ 57

8.2 Conclusions ........................................................................................................................... 60

9 References .................................................................................................................................... 62

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10 Appendix ................................................................................................................................... 66

10.1 Appendix A – HelioScope Individual Designs ........................................................................ 66

10.1.1 Non-Shaded Designs ..................................................................................................... 66

10.1.2 Shaded Designs ............................................................................................................. 67

List of Tables

Table 1: Number of TCEs in SUB13 ....................................................................................................... 23

Table 2: Chosen PV module specification ............................................................................................. 25

Table 3: List of inverters ........................................................................................................................ 27

Table 4: Breakdown of proposed components cost ............................................................................. 50

Table 5: Feasible components cost ....................................................................................................... 51

List of Figures

Figure 1: The location of Substation 13 .................................................................................................. 3

Figure 2: SUB13 kW Consumption data on 3rd April 2019 ...................................................................... 4

Figure 3: Example of HelioScope design ............................................................................................... 11

Figure 4: Example of row-to-row shading on HelioScope design ......................................................... 12

Figure 5: Example of Keepout Obstruction Shading ............................................................................. 12

Figure 6: Loss table comparison between HelioScope and PVsyst [15] ............................................... 15

Figure 7: Module placement for maximum PV generation .................................................................. 26

Figure 8: SUB13 full layout of electrical wiring design on HelioScope ................................................. 28

Figure 9: SUB13 revised design considering shading on HelioScope .................................................... 29

Figure 10: SUB13 2018 Load Demand ................................................................................................... 31

Figure 11: Grid failure situation ............................................................................................................ 33

Figure 12: Total cumulative and annual installed photovoltaic capacity in Australia [37] ................... 35

Figure 13: The energy generated by distributed PV systems in each state [37] .................................. 36

Figure 14: One-year data generation of the designed PV system ........................................................ 37

Figure 15: Sources of system loss of designed PV system .................................................................... 38

Figure 16: Overview of shaded designed panels [38] ........................................................................... 39

Figure 17: Non-Shaded vs. Shaded PV Generation ............................................................................... 40

Figure 18: PV generation only ............................................................................................................... 44

Figure 19: PV and battery generation only ........................................................................................... 46

Figure 20: SUB13 Load Demand during summer .................................................................................. 47

Figure 21: SUB13 Load Demand during winter ..................................................................................... 48

Figure 22: 25 Project Cash Flow ............................................................................................................ 52

Figure 23: HOMER simulation including all Microgrid components with grid ...................................... 53

Figure 24: HOMER schematic diagram of PV, battery and inverter ..................................................... 54

Figure 25: One-year battery condition from HOMER simulation ......................................................... 54

Figure 26: Inverter and rectifier output from HOMER simulation........................................................ 55

Figure 27: Only diesel generator connected to AC side ........................................................................ 55

Figure 28: Diesel generator and PV system connected on the AC side ................................................ 56

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Figure 29: From top left, B245, B235 and B240 designs without any shadings ................................... 66

Figure 30: From top left, B245, B235, and B240 designs with shadings ............................................... 67

List of Abbreviations

balance-of-system (BoS), 21

Battery Energy Storage System (BESS), 34

cost of electricity (COE), 8

cost-benefit analysis (CBA), 8

Desert Knowledge Australia Solar Centre (DKASC), 7

diesel generator (DG), 36

Distributed Energy Resources (DER), 1

Hybrid Optimization of Multiple Electric Renewables (HOMER), 16

Lithium-ion (Li-ion), 17

Murdoch University (MU), 1

net present cost (NPC), 8

Operation & Maintenance (O&M), 8

Photovoltaic (PV), 5

Property Development Commercial and Services Office (PDCSO), 3

single line diagram (SLD), 9

standard test conditions (STC), 21

Substation 13 (SUB13), 3

Temperature Controlled Environment (TCE), 9

Temperature-Controlled Environment (TCE), 4

three-dimensional (3D), 10

uninterruptible power supply (UPS), 1

University of New South Wales (UNSW), 19

vanadium redox-flow battery (VRFB), 18

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1 INTRODUCTION

In this modern era, on a global scale, one of the main priorities is the development of alternative

sources for power generation, such as the wind and solar energy, renewable biomass, and hydrogen.

These sources play an essential role in the long term and produce substantial changes for both the

environment and organization of the global energy system [1]. The demand of electricity for

commercial areas or buildings is very high, considering that there are critical loads that need to remain

energized at all times. This constant electricity supply has become a considerable concern, especially

when the amount of electricity gets interrupted or leads to a disaster at any unforeseen events. For

this reason, one uses an uninterruptible power supply (UPS) for the possibility to supply high-quality

electric power to the load even if failure from the main supply occurs.

A Microgrid is defined as a system characterized by a set of loads, energy storage systems, and small-

scale generation sources. These power sources can be photovoltaics, wind generators, and diesel

generators [2]. A Microgrid contains a portion of the electric distribution system in a medium and low

voltage. A variety of Distributed Energy Resources (DER) is included in the Microgrid system such as

distributed generators, energy storage, and different types of end users that provides for electrical

and thermal loads [1]. The Microgrid can supply to a range of customers, including residential

buildings, commercial entities, industrial parks, and non-interconnected zones [2]. It is also able to

import and flexible export energy from and towards the power grid generated by different types of

DER. On the other hand, if there are failures in the primary power grid, the Microgrid can isolate itself

from the rest of the power grid to avoid affectations to local loads by such problems [3].

Murdoch University (MU) has experienced several failures of the main power supply from the grid in

these recent years. This event has affected the students’ classes duration, laboratories experiments,

and putting a risk towards specimens stored in the biological laboratories. Other than that, MU as a

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24/7 operational commercial ground, the campus consumes a high amount of electricity, and it also

depends on the load demand of the area.

This thesis describes the feasibility study of Microgrid application for a particular area which was

proposed for the university to help meet the load demand and reduce such risks during the occurrence

of failure of main power supply. This thesis also will explain the performance of the chosen Microgrid

components to be integrated into the work and the capital investments of the components will be

researched and identified in the later sections of this project.

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1.1 PROJECT BACKGROUND

The project was first introduced by the consultants of Murdoch University’s Property Development

Commercial and Services Office (PDCSO). It is to look at the possibility of a self-generation when there

is no grid supply for Substation 13 (SUB13). SUB13 is a part of the electrical distribution that provides

electrical supply to its only dedicated precinct.

Figure 1: The location of Substation 13

The buildings that are associated with the project are marked with red:

- Building 245 – Science and Computing

- Building 240 – Biological Science

- Building 235 – Loneragan Building

The marked blue area represents the buildings that are not included in the scope mainly because B220

is for educational purposes and on the roofs of the buildings already has an existing PV system. Other

than that, the other buildings are acting as transporter buildings only.

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Figure 1 also shows the location of SUB13 marked as the yellow-square inside B245. There is also an

existing generator located in the same room, which will be further explained in the body of the report.

Figure 2: SUB13 kW Consumption data on 3rd April 2019

In the year of 2010, 2017, 2018 and recent 2019, SUB13 had experienced multiple grid supply failures.

An example shown in the figure above is to show a blackout scenario that occurred for approximately

two hours on a specific date. The whole campus experienced a zero electricity supply and had put

some potential risks to different areas. One of the affected was a Biology researcher that was

experimenting in one of the laboratories. During the two-hour blackout, the researcher’s specimen

was stuck inside the machine and had to be taken out by force. The whole experiment had to be

repeated. The grid supply failure had the potential of destroying one’s research that could affect the

university’s investment towards the specimen or the machinery.

Another risk that is to be avoided when there is a grid failure scenario is the Temperature-Controlled

Environment (TCE) such as the fridges and freezers located in the laboratories. An energy audit was

conducted to identify the amount of TCEs present and to separate between the critical and non-critical

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SUB13 kW Consumption Data on 3rd April 2019

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load. There is a count of 250 TCEs that stores specimens or samples that have been kept for more than

a decade and costs the university about AUD$15 million.

To avoid these risks in the future, an uninterrupted power supply (UPS) is required to meet the criteria.

In this given circumstance, a Microgrid application is a possible solution. SUB13 have the potential to

generate its electricity when there is a grid supply failure situation by implementing other renewable

sources such as Photovoltaic (PV) systems, battery energy storage systems along with the existing

generator in the precinct.

1.2 PROJECT OBJECTIVES

The aim of the project is not to only avoid TCE risk in the future but to also meet SUB13’s load demand

when there is no supply by the grid.

There are different scopes to look at in this research project. They include:

1. To look at the opportunity for PV systems generation on SUB13.

2. To identify roof space availability on SUB13.

3. To utilize HelioScope software as a tool to design the PV system.

4. To identify the requirement of battery and the size of the battery.

5. To analyze the performance of the implemented Microgrid application.

6. To analyze the cost of the proposed Microgrid application.

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2 LITERATURE REVIEW

This chapter discusses the previous works that had been studied and discussed by former Murdoch

University (MU) engineering students. The purpose is to gather the necessary background information

regarding the project that has been proposed by Project, Development, and Commercial Service

Department Office (PDCSO) since the year 2015.

2.1 PV System Design Analysis

The first thesis that was reviewed is by Ahmad Asyraf Emir Bin MOHD KHAIRY with his project entitled

‘Photovoltaic Generation Opportunity Analysis at Murdoch University.’ His thesis discusses the

opportunity of Photovoltaic (PV) generation that can be installed on Murdoch University (MU) by using

PV simulation software. Given the project by PDCSO, it aims to look at how PV systems can reduce

MU’s electricity load demand and the cost of the electricity.

MOHD KHAIRY chose two standard systems, a single-phase system with 5kW SMA Sunny Boy SB

5000TL inverter and a three-phase system with 15kW SMA Sunny Tri-Power STP 15000TL inverter. A

matching array calculation was studied to compensate for the 5kW single-phase system, which then

had led to the use of 275W Suntech STP275-Wem [1].

A site survey was performed, and MOHD KHAIRY discovered that MU has a suitable roof space to

install a PV system. A simulation software called PVsyst was the main programming tool for the project

and resulted in an energy output that can reduce 10% of electricity usage. The simulation generated

a total of 2239.85 MWh/year as opposed to the energy consumption of 22291.36 MWh/year [1].

MOHD KHAIRY’s work is to be taken into account as an improvement for the project. HelioScope will

be used for this thesis project for it was recommended by MOHD KHAIRY in his statement under Future

Works. It is also recommended to increase the size of the system by using large inverters and modules

to optimize the energy produced [1].

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To support the first thesis analysis, more information is needed in terms of simulation. The second

review is a thesis presented by Stephen Rose entitled ‘Performance Evaluation, Simulation and Design

Assessment of the 56kWp Murdoch University Library Photovoltaic System’. Rose had accessed the

performance of MU’s 56kWp, roof mounted PV system from August 2010 to July 2011 and also made

a comparison to the similar PV system from the Desert Knowledge Australia Solar Centre (DKASC) in

Alice Springs [2].

Rose had focused on the performance ratio (PR) of the system and compared the two type of silicon

modules, poly-crystalline (poly-Si) having slightly higher PR than the mono-crystalline (mono-Si) at

0.75 and 0.74 respectively. The results were then compared to DKASC's PV system [2].

The scope that can be taken from this review is the shading influences. Rose utilized the same software

MOHD KHAIRY had, which is PVsyst [1] [2]. It was found in Rose’s research through the simulation

software that due to the shading effects, the system output generated a PR average of 0.73 [2]. In

other words, the shading effect would reduce the performance of the PV system.

HelioScope has a better visual perspective of shading simulation compared to PVsyst, and this is to be

explained later in the body of the report in great details.

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2.2 Cost-Benefit and Economic Analysis

A chapter in this Literature Review will consist of the cost-benefit and economic analysis of the PV

system and battery storage installation. Details are to be gathered by two previous theses work with

the first thesis entitled ‘Cost-Benefit Analysis of PV and Storage Installation at Murdoch University' by

Sami Alhusayni and the second thesis written by Emily Salter, ‘Economic Analysis of Reducing End-

User Peak Demand with Renewable Energy.’

Alhusayni had used HelioScope to measure the roof space available for PV installation and found the

capacity for each orientation North, West, and East are 2MW, 500kW, and 600kW, respectively [3].

This capacity information can be a comparison to this project’s PV system design once the HelioScope

design model is completed. The chosen buildings for Alhusayni’s analysis would not be the same as

this project’s, but the reference using HelioScope would be relevant.

Another similar use of-of the software by Alhusayni that is to be implemented in this project is HOMER.

Given the load profile and rooftop capacity, Alhusayni used HOMER to find the optimum system

concerning cost and performance. The author had 8 trial and error simulations until the optimum

system was found, from altering the component’s size limits to maximizing converter component’s

limit, analysing the sensitivity of the operating and maintenance (O&M) costs, changing the system’s

size and performance and analysing the sensitivity of battery storage requirement to the system [3].

Alhusayni assumed the system had a project lifetime of 20 years and the grid purchase capacity is

reduced to 5300kW from 6112kW. The annual total energy is reduced from 22.291 GWh/year to 18.84

GWh/year. The initial cost of the system conducted from the cost-benefit analysis (CBA) was found to

be AUD$3.4 million. The author also had researched the cost of electricity (COE) and the net present

cost (NPC) to be AUD$0.15 and AUD$32.8 million respectively. It was also stated that the project’s

payback period was 4.4 years [3].

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Compared to the previous theses reviewed above, Salter’s research thesis does not contribute as

much about this project except to acknowledge Salter’s statement of moving loads to low demand

periods and improve the load efficiency as the best method to reduce peak demand [4]. This strategy

is connected to the project’s Temperature Controlled Environment (TCE) risk audit that had been

conducted as a preliminary task. It is mainly to identify which load is essential and non-essential, and

that is to be redrawn on a new Sub 13’s electrical single line diagram (SLDError! Bookmark not

defined.), which is weighing more on another ENG470 thesis student’s task, James Woodford, with

his thesis topic ‘A Reliability Study for the Proposed Substation 13 Microgrid at Murdoch University’.

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2.3 Simulation Software

The purpose of this chapter is to provide information and ideas through research and discussions with

professionals in the area of study, particularly on the designing aspect.

To optimize a PV system, it can be done in multiple ways of software of choice. For this thesis project,

HelioScope and PVsyst software are going to be analysed first since they share almost similar features,

before choosing as the most preferred simulation software. HOMER, as another software would be

applied for sensitivity and economic analysis purpose.

2.3.1 HelioScope

HelioScope was developed by Folsom Labs. It is an advanced PV system design tool that integrates

system layout and simplifies the modelling process at speed faster than normal [5] [6]. Other than

that, this software is new and commercially-available [6], HelioScope has a whole range of features,

such as a three-dimensional (3D) tool to design PV on the roofs, the ability to calculate shading when

one or more obstacles are surrounding the PV area, simulating values of the PVs operational behavior,

and also providing each Single-Line Diagram (SLD) for electrical experts. HelioScope is also accessible

at any place and at any time.

HelioScope and PVsyst use the same state-of-the-art mathematical models, and it uses weather files,

shading analysis, the physics of the solar modules and other features that run its simulation. In

comparison to PVsyst, to determine current levels, HelioScope measures the actual length and wire

models based on the layout to calculate wire resistance and its hourly sunlight/electrical production

values whereas PVsyst estimates wire losses based on simplified models. HelioScope can identify how

much of the current flow in each string, and it can calculate 𝐼2𝑅 losses more accurately. Not only that

but users can choose different components and run multiple simulations for the same location for

comparing purposes and identify the best design configuration [7].

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Figure 3: Example of HelioScope design

2.3.1.1 Shading in HelioScope

Shading is a phenomenon that is a total or partial blockage of sunlight from a PV module surface. It

can lead to a serious concern in PV arrays [8]. PV arrays should be installed in a shade-free location,

although this project involves PV installation onto the top of a commercial building which concerns

some inevitable shading. PV arrays get shadowed in different cases, complete or partially, by the

moving clouds, buildings, towers, or the row-to-row array shadow [8]. The effect of shading could

cause a reduction in the output of a PV array. This subject is to be discussed in depth in this thesis

concerning the research is a grid-connected system [9].

HelioScope has its world-class ability to model energy losses due to shading for a solar array. There

are two best practices for modeling shading in HelioScope:

1. Row-to-row shading: It is possible that the modules shade each other for fixed-tilt arrays,

especially if the row spacing is narrow or the tilt is high. The shade losses are automatically

calculated. The only way to modify the losses is if the user reduces the tilt angle or increases

the space between modules.

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Figure 4: Example of row-to-row shading on HelioScope design

2. Keepout Obstruction Shading: The shadows are calculated and applied on each module in the

array if a height is defined. The user-defined height will automatically calculate the shading

losses [10].

Figure 5: Example of Keepout Obstruction Shading

2.3.2 PVsyst

PVSyst is a PC software package for the study, sizing, and data analysis of complete PV systems. It

deals with grid-connected, stand-alone, pumping, and DC-grid PV systems. It also includes extensive

meteo and PV systems components databases, as well as general solar energy tools [11]. This software

simulator is designed to be used by architects, engineers, and researchers. It is a very educative tool.

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PVsyst presents results in the form of a full report, specific graphs and tables; also, data can be

exported for use in other software [12].

2.3.2.1 Shading in PVsyst

There are two types of shadings in PVsyst that are fundamentally distinguished:

1. Far shadings are described by a horizon line. They concern shadings from objects sufficiently

far as the users consider it will globally act on the PV field: at a given instant, the sun is or is

not visible on the field.

2. Near shadings are shadings produced by near objects, which draw visible shades on the PV

field [13].

Ahmad Asyraf stated in his research that the PVsyst defines the shading factors as the ratio on how

the shading will affect the system. The simulation requires the building's 3D to calculate the shading

factor [1]. This shows that HelioScope is more convenient than PVsyst in terms of visual 3D

assumptions.

2.3.3 HelioScope Vs. PVsyst

When calculating the energy yield of a PV array, HelioScope and PVsyst use almost all of the similar

equations. A third-party engineering firm, DNV GL, had verified the equivalence and confirmed that

the two models are within 1% at each step of the calculation [14]. The main comparison between the

two is that HelioScope calculates the system behavior at the module level, whereas PVsyst calculates

behaviour at the array level. Refer to Figure 6 for loss table comparison.

There are several small differences between PVsyst and HelioScope as the two software simulators

are not identical:

1. Mismatch from the individual module behavior and circuit effects can be calculated in

HelioScope, whereas PVsyst applies a loss for mismatch based on user-defined derates.

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2. While still based on user-defined derates on PVsyst in terms of wiring based loss factor,

HelioScope calculates wiring losses based on the resistance and current of each conductor

every hour.

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HELIOSCOPE PVSYST

Figure 6: Loss table comparison between HelioScope and PVsyst [15]

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2.4 HOMER

Hybrid Optimization of Multiple Electric Renewables (HOMER) software, created by HOMER Energy,

is a microgrid software and it is the global standard for optimizing microgrid design, from village power

and island utilities to grid-connected campuses and military bases. Both off-grid and grid-connected

power systems can be simplified and evaluated in the software [16].

Many possible system configurations such as the variation in costs, the large number of technology

options and the different choices of energy resources can be evaluated by using this simulation

software for its ability and its algorithms that can optimize and analyze sensitivity [16].

In each time step of the year, HOMER simulates the operation of a system by making energy balance

calculations. Based on the time step, electrical and thermal demands that can supply are compared,

and the flow of energy is calculated to and from each component of the system. Generator operations

are also determined, and batteries’ charge or discharge is identified in each time step. The software

tells the user if the electric demand is met under its specified conditions, and provides an estimate of

the installation cost and system operation over the lifetime of the project. The system cost calculations

account for costs such as capital, replacement, operation, maintenance, fuel, and interest [16].

Hence, HOMER is to be included in this thesis project with its ability to perform optimization,

sensitivity analysis and cost estimation, which then would lead to the economic evaluation that will

be discussed later in this report.

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2.5 Battery

Energy storage is required in most stand-alone systems, as energy generation and consumption do

not generally occur at the same time. The power generated from solar during the day has to be

temporarily stored when it is not required until certain events, including longer periods of overcast

weather [17]. The risk of PV’s intermittent power supply can be reduced by having a battery storage

system, and demand satisfaction can always be ensured [18].

Although a few PV systems in the MWh range have already been implemented, generally storage

capacities are in the range of 0.1kWh to 100kWh [17]. Lead-acid and nickel-cadmium batteries are

commonly used in PV systems today. Different types of batteries that are emerging may be suitable

for storage of renewable energy such as redox flow batteries and high-temperature sodium-sulfur

batteries. Comparison of different battery technologies can be an approach to guide battery choice

for specific user conditions [19].

Through further discussions with consultants from the PDCSO, it has been narrowed down to two

types of batteries for this project’s PV system. The batteries are to be chosen by its energy

performance, and charge and discharge rate.

2.5.1 Lithium-ion

Lithium-ion (Li-ion) batteries are a common type of battery for portable appliances such as computers,

cameras, and mobile phones. Due to the Li-ion batteries lower maintenance, superior safety and its

volumetric characteristics, they are recently leaning towards the utilization in power systems

application [20].

Solar powered energy plants requires high-efficiency energy storage systems. Batteries and super

capacitors as electrochemical systems can efficiently store and deliver energy on demand in stand-

alone power plants. It plays a crucial role in the electrical grid in integrated systems as it can provide

power quality and load levelling. The efficacy of batteries to be integrated with the solar powered area

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is directly related to its energy efficiency and lifetime. Indeed, lithium batteries are expected to

provide an energy return factor higher than that assured by conventional batteries such as lead-acid

batteries, in virtue of their high value of energy efficiency [21].

Li-ion battery exhibits a low self-discharge rate of below 8% per month, a long cycle-life (>1000 cycles),

and wide operating temperature ranges (-20 to 60⁰C for charge and -40 to 65⁰C for discharge). Its

disadvantage is that it is expensive and has limited thermal tolerance. It also requires a protective

system against cell degradation and thermal runway due to electrolyte decomposition [22].

2.5.2 Flow

Flow-type batteries can be considered between classical secondary batteries and fuel cells. Energy is

stored by driving electrochemical reactions in flow-type batteries. They consist of storage tanks that

contain a typical solution of metal stalks as well as an electrochemical reactor, typically a cell stack,

capable of electrically charge and discharge the salt solutions. There are potential advantages to

compare flow-type batteries with solid-state batteries which firstly it does not have self-discharge

during the storage period. Secondly, during charge and discharge, there are no solid-state phase

changes [23].

For example, vanadium redox-flow battery (VRFB) can be considered as a suitable candidate for load

levelling/peak shaving and as a seasonal energy storage device in photovoltaic applications. It has

received considerable attention in the photovoltaic generation due to its various benefits.

Furthermore, by adapting the number of cells, the independence of performance (power output) and

capacity of the battery are achieved, and the electrolyte volume meets the requirements. A high life

cycle is to be expected with its tolerable deep discharge. Promising economic aspects can be offered

with this battery’s specific properties that certainly mean considerable advantages over conventional

storage systems such as lead-acid battery [24].

VRFB generally can achieve an energy efficiency of up to 85% with a 12000-year cycle-life. The system

does not have cross-contamination problems since the same vanadium species with different

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oxidation states is used in each cell. This allows the electrolyte to be recycled in the cell, leading to a

long cycle-life, and the cost of the battery system can be reduced. Moreover, in a short period, the

fast electrochemical reactions of vanadium redox couples allow the VRFB to become highly

discharge/charged. However, the disadvantage to this battery system is for its practical applications

as it has a low specific energy density (10 − 30 𝑊ℎ 𝑘𝑔−1). At present, although all of the VRFB

systems have been widely used in applications for load-levelling, it is still expensive.

2.5.1.1 Battery application in universities of Australia

Monash University has installed a combination of batteries, a 180kW/900kWh vanadium redox flow

battery system and a 120kW/120kWh C1-rated lithium battery for a 2MW of PV on campus. The

vanadium flow system, manufactured by red, can deliver up to 80% of the demand/supply and can

store energy for more than four hours. The battery contains permeable membranes that filter the

positive and negative half-cells to charge and discharge the battery. The advantage of the technology

is that the batteries can be discharged to zero and includes a long shelf-life of 25 years, also a high

level of recyclability. The lithium battery is used for occasional bursts of short demand spike and can

store energy for 1 to 2 hours [25].

The University of Adelaide, in South Australia, has recently reported in March 2018 that the university

will install 1.2MW of solar and a 0.5MW/2MWh vanadium flow redox battery at its campus [26].

The University of Queensland is going 100% renewable with 64MW solar farm including

600kW/760kWh of lithium-ion battery storage, with a further 1MW/2MWh of batteries due to come

online in early 2019, as well as energy storage in the form of 3 million liter chilled water storage tank

expected the next 12 months. It is stated that more storage is planned and could include batteries,

pumped hydro, or hydrogen technologies [27].

The University of New South Wales (UNSW) is the first university to implement an industrial-scale

Tesla Powerpack battery in Australia sized 500kWh for a 112kW rooftop solar array. The university

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has a similar goal to this project, which is to offset energy use at the campus and reduce demand from

the grid during peak times and reduce power costs [28].

2.6 Photovoltaic Economic Analysis

Photovoltaic energy is one of the most promising emerging technologies. The installation of PV has

increased in growth worldwide since 2010 [29] and it has taken a major step towards acting as a good

alternative to conventional energy resources to lower 𝐶𝑂2 emissions and meet the increasing global

energy demand [30]. Global PV capacity has been increasing at an average annual growth rate of more

than 40% since 2000, and it has significant potential for long-term growth over the next decades [31].

In Australia, solar PV systems are the key of interest and growth in energy storage, whether residential

and commercial. Electricity prices are often increasing and decreasing, depending on the

environmental reasons and seasons [32].

The value of PV generated power can be viewed from multiple perspectives. The issues such as the

use of capital, environmental impact, and climate change and access to power are taken into account

from a global view. Societal, there could be local impacts to where the PV is being installed, and it

might include trimming such blocking trees surrounding the PV. Other societal aspects could include

manufacturing, employment, and cost of power, security, and diversification of energy supplies, the

balance of trade and infrastructure. Individually, it may lead to its initial cost, increased in house value,

but yet there will be a reduction in utility bills, and provide energy independence. From the utility

perspective, the value of PV output has relation to demand profiles, impact on capital works, ‘green

power' or mandatory renewable energy requirements and maintenance [33].

2.6.1 Economic Analysis

It is a dilemma for wider PV systems costs to be lowered if it is discouraged by the high initial capital

investment cost. To promote a large PV installation system in the hope that lower cost of deployment

could be obtained in the future, policies have different forms of economic incentives to compensate

for the high investment cost [34].

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The sizing of PV systems also affects the cost structure. For example, the watt peak, the nominal value

used for the sizing of PV systems, is the nameplate power that a PV module can generate under the

standard test conditions (STC) of 1000𝑊/𝑚2 insolation, 25⁰C cell temperature and an air mass of 1.5.

Realistically, it depends on the location as the hour-by-hour insolation varies through the year, and it

peaks at different values. The sizing of PV systems in most cases is based on either annual average or

the worst month average. The actual PV system performance might not match the designed

performance. Moreover, in evaluating the capability of PV systems to meet the building’s power

consumption is to assume the same daily consumption load profile for the entire year or to adopt an

annual total consumption [34].

The cost of the mounting structure, wiring, inverters, cost of installation and all other upfront costs

can be included in the calculation of capital investment of the PV systems as the sum of the cost of

the PV modules and the balance-of-system (BoS) [34].

HOMERcan performs the cost-benefit analysis through its sensitivity analysis. Trial and errors might

be required due to certain things that could be altered or changed. In this case, the amount of capacity

to be sold back to the grid, and the size of the battery will have a significance when analyzing this

system.

Other potential components, such as maintenance costs and another minor cost, are to be further

research and discussed with the PDCSO staffs.

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3 PRELIMINARY WORKS

A full audit of the buildings within the SUB13 was a requirement in the early stages of the project to

locate all of the recorded TCEs and also to identify the point of each electrical supply available. The

objective of this energy audit was to determine which distribution boards in each building are

considered as the critical load and that it is required to remain energized during a power failure to

service its connected electrical TCE loads.

Microsoft Access that was made available from within the PDCSO file structure was used to establish

the exact location and number of the TCEs. The TCEs were also cross-referenced, and the lists were

separated within its respected buildings (245, 235, and 240). These lists were further broken down

into standalone assets, such as plug-in fridges and freezers, and walk-in assets, such as large fixed cool

or warm rooms. This database also includes the TCEs information such as its associated building

number, room number, the barcode maintenance number, the manufacturer’s type and model of the

electrical circuit ID. However, due to the large size of the list and insufficient time, the process of

entering the data into PDCSO’s database was incomplete.

During the audit, it was established that only the TCEs that is highly critical such as the important data,

research, chemicals, or artefacts would be considered into the database. Others such as standard

kitchen fridges would be excluded. Table 1 below shows the recorded number of critical TCEs within

the SUB13 precinct with a total of 255, which includes 226 standalone and 29 walk-in assets. The

majority of these recorded TCEs are found within the laboratory facilities within B240 Loneragan (total

of 110) and B240 Biological Sciences (total of 106). B245 Science and Computing has 39 in total, and

the rooms included are mainly offices and teaching spaces.

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Table 1: Number of TCEs in SUB13

Building No. Standalone TCEs Walk-in TCEs Total

235 97 13 110

240 93 13 106

240 93 13 106

245 36 3 39

Total 226 29 255

The audit proved to be a slow and tedious task, mainly due to the large area to be covered within the

buildings, further restricted by the availability of a set of master keys from the maintenance

department which allowed access into all the necessary rooms and labs within the associated

buildings. This being said however, the audit was conducted successfully, with greater than 95% of the

recorded TCEs located, barcodes cross-referenced and electrical supplies recorded. A small number of

standalone assets, seven of 255 or approximately 3% were unable to be located. This audit then paved

the way for the next task within the project.

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4 HELIOSCOPE

This thesis research utilizes HelioScope software to design the PV system. As previously discussed in

Chapter 2, HelioScope is a good educational tool and an advance PV system designer software.

HelioScope has the features and ability to design and to place the modules onto the roofs of a targeted

space. The software also allows the user to create the structure of the building from the base to the

rooftop, which the pitch of the angle can be set to replicate the real building’s architecture.

The associated buildings of SUB13 which are the B235, B240 and B245 has multiple roof spaces on

different orientations, and this makes the task simple for the designer or the author to easily virtually

place the chosen modules. Any ventilation or penetrations from the roofs are avoided. The rest of this

chapter is to explain the module selected for the proposed PV system design, to provide an example

of the PV system design taken from the HelioScope software, to provide the list of inverters used

within the system and to also revise the proposed design with some shading effects.

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4.1 MODULE SELECTION

The specifications of the PV module to be used for the design were discussed with the consultants

from PDCSO. The reason for LG manufactured panels is mainly because it is a typical module in the

market today. The product has a longer life cycle and is considered Australia’s best PV modules. Given

such options, the university would only go for the higher quality, recommended, and of the excellent

measure types of PV modules.

Table 2: Chosen PV module specification

Name LG395N2W-A5

Manufacturer LG

Power (W) 395.0

𝑽𝒎𝒑 (V) 40.4

𝑽𝒐𝒄 (V) 49.1

𝑰𝒔𝒄 (A) 10.46

𝑰𝒎𝒑 (A) 9.78

Technology Si-mono (72 cells)

Dimensions 1.024m x 2.024m

Temp Coefficient 𝑷𝒎𝒂𝒙 (%/⁰C) -0.36

Temp Coefficient 𝑽𝒐𝒄 (%/⁰C) -0.27

Temp Coefficient 𝑰𝒔𝒄 (%/⁰C) 0.0003

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4.2 PV SYSTEM DESIGN

Figure 7: Module placement for maximum PV generation

Figure 7 shows the top view of the SUB13 associated buildings that were virtually designed using the

HelioScope software. As previously mentioned in Chapter 4.1, 395W rated modules manufactured by

LG were chosen and placed onto the empty spaces of these buildings. The idea is to fully optimize the

roof spaces available to obtain a maximum available PV generation on this network. In the software,

the modules are set to no limitations or constraints such as zero distance from modules to modules,

and zero distance from every corners and edge. In total, there are 2911 panels that can be placed onto

the roofs with a total capacity of 1,150kW (or 1.15MW). The individual designs of each building are

made available in Appendix A.

Observing the same figure above, the blue coloured areas are the PV modules, whereas the orange

coloured squares and rectangles are KeepOuts (Refer to Chapter 2). As mentioned before, the roofs

of these associated buildings are looked into detail with the help of Google Maps to avoid placing the

modules on the ventilation systems or any penetrations from the roof.

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According to CEC guidelines, to facilitate the efficient design of PV systems, the inverter nominal AC

power output cannot be less than 75% of the array peak power, and it shall not be outside the inverter

manufacturer’s maximum allowable array size specifications [35]. With the rated capacity given,

several different inverters were used on different orientation. This is due to the size of each building;

therefore, the software automatically calculates the length of the wiring.

Table 3: List of inverters

Name Building Count kW

Sunny Tripower 20000 TLEE (SMA) B235 1 20.0

Sunny Tripower 15000TL-US (SMA) B240 1 15.0

ST 42 (277) (SMA) B240 1 42.0

Sunny Central 80 kVA (SMA) B245 3 264.0

Sunny Central SC 90 (SMA) B235/B240 2 180.0

Sunny Central SC 200 (SMA) B245 1 200.0

Sunny Tripower 30000TL-US-10 (SMA) B235 1 30.0

Sunny Tripower 12000TL (SMA) B240 6 72.0

STP50-40 (SMA) B240/B235 2 100.0

Sunny Tripower_Core1 33-US-41 (SMA) B235 2 66.6

Sunny Tripower_Core 1 62-US-41 (SMA) B235 1 62.5

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Figure 8: SUB13 full layout of electrical wiring design on HelioScope

When it comes to designing a PV system, it is a standard to evaluate and assess the performance of

the chosen inverters as well as its wiring and cabling of the design. In this given circumstance, AS/NZS

4777 and AS/NZS 5033 is relevant to be looked at and should be complied for this project. This task

shall be promoted in future works.

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4.3 REVISED DESIGN CONSIDERING SHADING

Shading is one of the key parameters when designing a PV system. Murdoch University campus has

an eco-friendly ground space, and SUB13 is mostly surrounded by trees. This will cause some shading

effect on the PV cells. Upon discussion with the PDCSO consultants, it has been established that the

required design for this project is to exclude the surrounding obstacles that will potentially shade the

panels for a certain time. Removal of the trees was also considered in the discussion. Therefore,

throughout the research of this project, the PV system design chosen will not be considering the

surrounding trees.

This chapter is to analyse the significant difference between the shaded system design with the non-

shaded system design.

Figure 9: SUB13 revised design considering shading on HelioScope

Figure 9 shows the revised PV system design of SUB13 on HelioScope. By using Google Maps, the trees

surrounding the areas were put into the software with estimated height and diameter. HelioScope has

the ability and feature to calculate the shading, which means that the software will remove the panels

that are getting shaded. As observed in the figure above, panels that were removed are mostly from

the edges and corners of the associated buildings. The original unshaded design could fit the roofs

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with 2911 panels, and then the shading has affected the number of panels down to 2424 panels to fit

onto the roofs. The PV generation of SUB13 in this given circumstance is 17% lesser compared to the

original design in Chapter 4.2. To view the individual designs with consideration of surrounding trees,

refer to Appendix A.

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5 REQUIRED DATA

The load data that displays the electrical demand of the targeted network plays a huge role in this

project. It provides the critical information such as the occurrence of the peak load and the duration

of the peak load period. The load data will also vary depending on the time of the year, week, or even

the day.

This research project requires historical data to analyse the load demand required. The following data

shown in Figure 10 was taken from PDCSO Schneider’s Building Management Software (BMS). It is a

dedicated software to read and store the meter data from the installed power meters manufactured

by Schneider.

Figure 10: SUB13 2018 Load Demand

The figure above shows the measured kW consumption from the year of 2018. The three different

trends represent,

Transformer 1 (TRF1) kW consumption

Transformer 2 (TRF2) kW consumption

0

200

400

600

800

1000

1200

1400

1/0

1/2

01

8 1

2:3

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M1

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M1

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M1

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:30

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/20

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M1

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25

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:30

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:30

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AM

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/04

/20

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8:0

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M6

/05

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6:3

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M1

6/0

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:00

:00

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27

/05

/20

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3:3

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M6

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/20

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M1

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/06

/20

18

11

:00

:00

…7

/07

/20

18

9:3

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M1

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28

/07

/20

18

6:3

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/08

/20

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M1

8/0

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/08

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M8

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M9

/10

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M2

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8 6

:30

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AM

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/10

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M1

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M1

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AM

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/20

18

11

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…2

1/1

2/2

01

8 9

:30

:00

PM

kW

SUB13 2018 Load Demand

TRF1 (kW) TRF2 (kW) SUB13 (kW)

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Sum of TRF kW Consumption

Both transformers are connected to different parts of the precinct.

Transformer 1 (TRF1) powers B245 and B240.

Transformer 2 (TRF2) powers B235

A different situation occurred during SUB13 data compilation due to TRF1 has no real measured data

from the beginning of 2018 until August 2018 when its meter was commissioned. TRF2, on the other

hand, has an existing whole year measured power consumption data. In this circumstance, TRF1’s

consumption had to be estimated by correlating a similar pattern to TRF2. Both of the load profiles

are then summed up individually to gain an overall consumption labelled as SUB13 (kW). In August, in

the same figure, it shows a communication error that occurred. This could be the malfunction of the

meters, or the meters were not communicating to the PDCSO’s BMS. The error occurred for a little

while until it was fixed.

By observing the same figure, the consumption peaks at 584kW throughout the year. It is assumed

that the appliances, lights, TCEs, classrooms, computers, etc. are highly consumed during this term of

the semester. The general load profile requires 331kW of baseload, and this is the energy required to

power the 24hour operated TCE.

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6 MICROGRID APPLICATION

This thesis research is also to aim to implement a microgrid application into SUB13 network.

“[A microgrid is] a group of interconnected loads and distributed energy resources within clearly

defined electrical boundaries that act as a single controllable entity concerning the grid. A microgrid

can connect and disconnect from the grid to enable it to operate in both grid-connected or island-mode

[36].”

This chapter is to explain the situation of the microgrid flow during a grid supply failure situation. The

body of this chapter will also describe the specifications and size of the existing and the non-existing

microgrid components that are required to achieve the objective of this project.

6.1 MICROGRID FLOW

Figure 11: Grid failure situation

Figure 11 demonstrates the flow of microgrid application that meets the load demand of SUB13. This

illustrates the situation of the microgrid network when there is no supply from the grid. In this given

circumstance, when there is a zero supply from the grid, the distributed energy resources such as the

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Photovoltaics (PV) system, diesel generator, and the battery will generate electricity for SUB13 as an

independent electricity supplier.

Since the PV system is a capacity of 1.15MW, there is a potential of oversupplying of energy during

the presence of high irradiance. The excess energy from the PV system would be prioritized to charge

the battery if the battery energy storage system’s (BESS) state of charge is below 100%. Once the BESS

has been fully charged, if there is still presence of the excess energy, it would be distributed to the

other precinct in need. This distribution would apply in this circumstance since the network is

connected to the grid.

The scenario that best fit this research to achieve the objectives would be when there is no grid supply

for 24/7. That means the analyzation of the Microgrid components for this project would be based on

a 24hour operation.

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6.2 PHOTOVOLTAICS

The photovoltaic industry within Australia has a rapid growth since April of 2001 with a reported

installed capacity of 516kW. As years went by, growth in the trend started to show commencing the

year of 2010. As of 30 September 2018, there are over 1.95 million PV installations in Australia, with

a combined capacity of over 10.14 gigawatts [37], as shown in Figure 12.

Figure 12: Total cumulative and annual installed photovoltaic capacity in Australia [37]

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Figure 13: The energy generated by distributed PV systems in each state [37]

A significant increase between states reported by the Australian PV Institute, as shown in Figure 13.

January 2019 shows that Queensland is dominating the industry at more than 330,00MWh. Western

Australia (WA) started with 43,684 MWh in April 2015, and a total of 174,409 MWh in January 2019

[37]. These statistics state that the WA monthly PV output from 2015 until 2018 has increased by

approximately 74.95%.

Installing a PV system on the associated buildings of the SUB13 precinct would be a viable source of

diesel generator (DG) as this makes use of the existing infrastructure. Moreover, it is an advantage to

utilize the empty spaces of the targeted buildings, as discussed in Chapter 3.

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Figure 14: One-year data generation of the designed PV system

A typical Perth’s solar generation pattern can be seen in the figure above. It is a one-year generation

of data provided by the designed PV system from HelioScope (Refer Chapter 4). The PV system

designed for the commercial buildings summed up to a total of 1.15MW of capacity. Based on the

figure above, the irradiance of the sun is high during the summer. Therefore, the system could

generate up to 1,150kW. As the year approaches towards the middle which the season changes to

winter, the irradiance gets lower, and the skies are mostly covered with clouds. December as expected

to be the best month of solar generation in Western Australia has a peak generation of 1123kW

compared to the worst month of a generation, which is June at 544kW.

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6.2.1 Sources of System Loss

Not all PV systems are designed to operate at 100% due to particular matters such as sources of system

loss shown in the figure below. There is a total of 29.7% of losses for the designed system.

Figure 15: Sources of system loss of designed PV system

As observed, the temperature of the PV modules contribute to the highest loss percentage for the

entire system, which is up to 9.7%. This is possible due to the layout of the modules that cause the

power to decrease as temperature increase.

There are other general factors that lead to the losses of the system, and it has to be taken into

account. Another parameter that should be focused on for this thesis is the shading effect. A total of

3.1% of the system is affected due to the row-to-row shading. The south side of the precinct is also

mostly shaded. This is possible due to the insufficient presence of irradiance on that particular

orientation.

6.2.2 Shaded and Non-Shaded PV Generation

Presence of shading always needs to be taken into consideration when designing a PV system, as

previously discussed. Figure 16 below shows an overview of the shaded panels on the roofs of SUB13.

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Due to the zero limit of constraints, there are no gaps in between the designated panels. Therefore,

each panel is getting shaded by the ones placed in front or it is known as row-to-row shading.

Figure 16: Overview of shaded designed panels [38]

Referring to the same figure above, it is showing the heatmap of the shaded panels. The simulator

indicates a higher potential shading as the colour of the panel goes from blue to red. Due to the given

circumstance, the PV capacity is expected to be reduced compared to the non-shaded design. As

previously discussed in terms of shading, there is a total of 3.1% losses due to shading. Refer to the

figure below for its significant difference.

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Figure 17: Non-Shaded vs. Shaded PV Generation

Figure 17 above shows a year of 30 min interval chart between shaded and the non-shaded design.

During the summer season, panels that are getting shaded peaks at 924kW and could supply power

to the base load at 177kW. Overall the difference between the two scenarios of the PV generation has

a 20% difference. Regardless of the dissimilarities, the PV system is still expected to have a high

amount of excess energy since the non-shaded PV system has a capacity of 1.15MW, whereas the

shaded has a 957.5kW sized PV system.

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6.3 DIESEL GENERATOR

The most common and popular form of traditional non-renewable diesel generators and are part of

the reciprocating machine category are the diesel generators.

The existing generator located inside of B245 is the size of the 200kW generator. It uses a diesel engine

to run the electric generator to produce electricity. When there is a failure of supply from the grid, the

diesel generator has been utilized as a black start for the SUB13 precinct, mainly to generate electricity

for the computer server rooms.

This diesel generator, however, can only supply energy up to 200kW, which means that it potentially

would not meet the load demand needed by SUB13. The performance of this renewable source

component will be analysed in details to identify if it’s suitable to be paired with both PV and battery

to achieve the aim of this study.

The diesel generator, on the other hand, is considered as a highly reliable source of generation and

requires regularly scheduled maintenance to ensure that it achieves its extended lifespan. The DG also

needs to be ensured that both start-up and normal run failures are minimized given that it is regularly

checked and maintained. In terms of maintenance, the critical part that needs attention to be invested

on is its diesel fuel as the diesel level is required to be monitored and maintained above its minimum

range at all times based on its specifications. Generally, diesel generators as a piece of the standalone

system are considered to operate between an approximate of 95% availability, which is a lower figure

than the availability of most typical electrical supply utilities [39].

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6.4 BATTERY

When the power supply is absent from the grid, other microgrid components can act as a backup

source. In this case, another alternative solution would be the power supply from the energy stored

in the battery bank.

Lithium-Ion would be the type of battery to be integrated with the SUB13 microgrid network as this

has already been discussed and confirmed with the PDCSO staffs. As discussed in Chapter 2, Lithium-

Ion holds different advantages such as it contains a high energy density; it can self-discharge, they

don’t require frequent maintenance to ensure their performance, no need for priming and lithium-

ion comes in a variety of types available [40].

6.4.1 Battery Size

When designing a microgrid application, the size of the battery is very important. The battery must

have the capacity that will cover the required load. To determine the size of the battery, the historical

data of the year 2018 for SUB13 network is analysed and calculated manually on the spreadsheet.

Throughout the year given from the historical data of 2018, SUB13 peaks at 463kW. This determines

the maximum energy demand that the battery needs to supply. In terms of the energy that the battery

needs to store, it is based on the maximum kWh on any day throughout the year. The highest energy

consumed based on the historical data would be near the end of May with 7193kWh after getting

supplied by PV. Therefore, the battery size needed to meet the load demand of SUB13 is

463kW/7193kWh.

The size of the battery required also seeks the attention of an energy storage specialist(s) for a

1.15MW PV system and also for commercial terms regardless. The battery could also be sized in

another method which is through HOMER.

HOMER, as explained under Chapter 2, is a handy tool and said, would benefit this study in terms of

optimization, sensitivity analysis, cost evaluation, and economic evaluation. However, after several

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attempts of trial and error, the analysis of this simulation tool has halted at a certain point. This is

because of some disadvantages that were discovered along with the progress which its solutions were

inaccurate for the project.

The tool is still suitable to analyse the cost analysis of the project, but it is not appropriate for battery

sizing nor generator scheduling.

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7 RESULTS & ANALYSIS

7.1 MICROGRID PERFORMANCE ANALYSIS

This chapter will provide the results of the manual simulation that was calculated by using a Microsoft

Excel spreadsheet. The important cases that would be shown would be the chart of the network being

supplied from the PV systems only and also a chart that explains the network being supplied by all of

the Microgrid components, the PV system, battery supply and diesel generator.

7.1.1 Potential of Solar Generation

Microsoft Excel spreadsheet was used to analyse the performance of the integrated Microgrid

components that consists of 1.15MW capacity of the designed PV system, 200kW diesel generator,

and 463kW/7193kWh battery energy storage system.

Figure 18: PV generation only

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The above figure is to provide a look at the SUB13 load demand when it is only being supplied by the

1.15MW PV system. The data taken is an example of a day in the winter season for the year 2021.

Figure 18 also shows a 24-hour operation without any grid supply. The blue line illustrates the load

demand of the network while the orange line is the solar generation. The grey line in the chart

represents the load demand after it is supplied by the proposed PV system.

As observed, during the off-peak hour’s operation, and if there is a situation of grid failure supply, the

load demand of SUB13 is not met due to insufficient renewable sources. The irradiance of the sun

during the off-peak hours is obviously zero, and SUB13 would be left as a blackout. Approaching day

time or in other words, the on-peak hours operation, the irradiance of the sun gradually increases and

peaks when the sun is located high in the clear sky during the mid-day. The load demand of SUB13 is

met as it is getting supplied by the available solar generation and produce excess energy at

approximate of 150kW. Since this is an example of only PV system generation and no battery energy

system storage, the excess energy is not required to charge anything except that it could be supplied

to the other precinct.

The pattern of the chart returns as it initially started when the day approaches towards the off-peak

hours. The irradiance of the sun decreases to zero, leaving the SUB13 precinct not being supplied by

any available electricity generation for a grid supply failure scenario.

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7.1.2 Potential of Solar and Battery Generation

Figure 19: PV and battery generation only

For this scenario, the battery system is added into the network to supply electricity during the off-

peak hours since, at these duration, the load demand was not met as previously discussed in Chapter

7.1.1. Figure 19 as shown above illustrates the predicted performance of a day in the summer of 2021.

As observed, the load demand that is shown as the purple line is met at night time provided the

generation from the battery system. The yellow line that represents the state of charge of the battery

is showing that the battery discharges during the off-peak hours and getting charged by the PV

generation during the day.

The same solar generation appears on the figure above, as discussed under Chapter 7.1.1. The high

generation during the day time provides the opportunity to charge the battery with some excess

energy at approximate of 700kW. In this given circumstance, this excess energy can also be distributed

to the other precinct.

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7.1.3 Potential of Microgrid Generation

The sub section of this chapter will discuss the possible generation of all Microgrid components

integrated into the system. The performance analysed would be based on summer and winter to

identify if the load can be met at different irradiance conditions.

Figure 20: SUB13 Load Demand during summer

Figure 22 above shows the load demand of the proposed network of a certain day during the summer

season. It shows all of the Microgrid components that are included to supply electricity for 24 hours.

Observing the line of ‘SUB13 Load Demand (kW)’, the network maintains a load demand average of

300kW. During the off-peak hours or during the night time, there is no solar generation. Approaching

the day time when the irradiance of the sun increases, SUB13 is then getting supplied by the PV

system. The PV generation peaks more than 1000kW and is able to charge the battery. SUB13’s load

demand is met, and also the Microgrid system is left with an approximate of 800kW of excess energy.

Referring to the Microgrid flowchart in Chapter 6.1, this is the opportunity to use the excess energy

to supply to the other precinct since the battery is 100% fully charged.

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As the irradiance of the sun decreases, the generation from the PV system also slowly decreases. The

absence of the solar switches on the other Microgrid components such as the battery and the diesel

generation. Given the circumstance, the battery is discharged during this period to meet the load

demand of SUB13. The battery then gets charged by the solar during the day. The diesel generator is

not used on this day since the load demand is met just by the battery and the PV.

The high irradiance during the summer gives an advantage to the 1.15MW PV system to generate a

lot of electricity and providing an amount of excess energy that can be used to charge the battery and

distribute the excess power to the other precinct in need during a grid supply failure.

Figure 21: SUB13 Load Demand during winter

Approaching the middle of the year comes the winter season. Figure above shows the network’s load

demand for a certain day in June. Comparing to the summer season, the load demand of SUB13

increased to more than 400kW.

During the off-peak hours, the diesel generator supplies electricity to the precinct. However, the diesel

generator can only supply up to 200kW, leaving the load demand not to be met. The battery in this

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given circumstance is not supplying any energy to the network because it has an insufficient state of

charge.

The irradiance of the sun is very low during the winter, as shown in Figure 14 under Chapter 6.2. This

affects the condition of the battery, as shown in Figure 23 that the battery is left at 0% of charge from

the day before. Hence, the battery cannot meet the load demand at night time. When the irradiance

of the sun increases in the day, the SUB13 load demand is met. However, the energy provided by the

PV system could only charge the battery less than 5% as observed in the same figure, the battery only

supplies energy for roughly two hours before the state of charge condition returns to 0%.

For a worst-case scenario where there is no grid supply for 24/7, the condition as expressed in the

Figure 21 above cannot be implemented to achieve the objective of this project because the load

demand of SUB13 is not met. The battery needs sufficient energy from other sources to be charged to

be able to meet the load demand of SUB13 during the off-peak hours.

On the other hand, the green line that illustrates the performance of the DG appears to have slightly

rise in between 4.48pm to 7.12pm. Reader should note that this is due to the default settings from

Excel which is unavoidable and that the DG is set to only generate electricity at 200kW.

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7.2 ECONOMIC ANALYSIS

The economic analysis has been considered into this project to identify if the proposed Microgrid

components are going to cost the university and is it going to be cost-saving for the university in the

future. This chapter of the thesis report is to provide the cost of the Microgrid components that were

used for this thesis project by analysing the price of the recent market.

Table 4: Breakdown of proposed components cost

Components Size Unit Assumed Value per Unit Component Cost

Photovoltaics 1150 kW $ 1,352 kW $ 1,554,800

Diesel Generator 200 kW $ 1,000 kW $ -

Battery 1 7193 kWh $ 700 kWh $ 5,034,974

Battery 2 8149 kWh $ 700 kWh $ 5,704,249

Battery 3 9255 kWh $ 700 kWh $ 6,478,640

Inverters 1052 kW $ 800 kW $ 841,600

There has been a rapid growth of Photovoltaic installations in Australia, as previously discussed in

Chapter 6.2. There is a potential for a decrease in market value for PV modules in the coming future.

Table 4 above shows an assumed value of the price per kW module at $1,352. The designed PV system,

as proposed in the body of the report with 1,150kW, would cost MU up to 1.5 million Australian

dollars.

The diesel generator is already an existing component; therefore, there is no requirement to invest in

a new diesel generator.

As observed in the same table above, there are three different battery pricing. These batteries that

range from 1 to 3 are based on the scenario that requires the battery to operate on. The characteristics

of these different scenario of batteries are assumed to be the same.

Battery 1 – Operates in parallel with PV and diesel generator.

Battery 2 – Operates in parallel with only PV.

Battery 3 – Operates in parallel with only grid.

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As previously discussed in Chapter 6.1, the scenario chosen for this report would be the worst-case

scenario that defines no grid supply for 24/7 and requires the renewable components to generate

electricity for 24/7. This establishes that the choice for Battery 3 would not be the principle choice

since it defies the aim of this project. Battery 2, also as has been discussed in Chapter 7.1, would not

be viable to achieve the objective. Therefore the feasible theory that would best fit would be the

choice of Battery 1. The market price for battery per kWh is also assumed, as shown in the table above,

and the university would need to invest another $5 million AUS dollars. The inverters add another

$840,000 AUS dollars to the investment of the components cost, which would bring to a total of 7.4

million dollars. Table 5 below shows the viable idea of the components cost.

Table 5: Feasible components cost

Components Size Unit Assumed Value per Unit Capital Cost

Photovoltaics 1150 kW $ 1,352 kW $ 1,554,800

Diesel Generator 200 kW $ 1,000 kW $ -

Battery 1 7193 kWh $ 700 kWh $ 5,034,974

Inverters 1052 kW $ 800 kW $ 841,600

$ 7,431,374

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Figure 22: 25 Project Cash Flow

Figure 22 shows the cash flow of the project for 25 project lifetime. The values were mainly focused

on the capital investment cost that was discussed in Chapter 7.2. The figure above illustrates the initial

investment of the Microgrid components approximately at AUD$7 million. Annually the cash flow is

assumed to be subtracting with at least AUD$500 cost for operation and maintenance, but at the same

time saving at least AUD$300,000-$500,000 (assumed values) on grid purchase. Approaching the mark

of the 16th year, which is the year 2036, revenues are starting to surface for the university.

Electrical components tend to degrade over time. Therefore, replacements have to be taken into

place, and it is assumed the cost of replacement is approximately AUD$4.5 million. The replacements

include all components, assumed some of the PV panels, the replacement of diesel generator and the

battery system. Reaching towards the 25th year of the project lifetime, the values are seen to be

resurfacing on the positive side.

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7.3 HOMER ANALYSIS

Figure 23: HOMER simulation including all Microgrid components with grid

Figure 23 illustrates the simulation of the proposed Microgrid system using the HOMER software.

Although the performance was analysed manually by using the Microsoft Excel spreadsheet, a look

into the HOMER sensitivity analysis software would add further critical-related information towards

this project. HOMER also can import solar generation data, and one of its features is a direct import

from the HelioScope. The rest of the components chosen were chosen and set accordingly as specified

for the project.

The rest of this chapter would mainly focus on the operation with no connection to the grid since this

research has been focusing on the worst-case scenario of no grid supply for 24/7. Therefore the grid

would be taken out for the next analyzations.

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7.3.1 Battery, Solar and Inverter Only

Figure 24: HOMER schematic diagram of PV, battery and inverter

Figure 26 shows a situation where there is no grid supply nor diesel generator supply. The Microgrid

system is being generated or supported by the 1.15MW system and 7MWh battery energy storage

system.

Figure 25: One-year battery condition from HOMER simulation

From the simulation of HOMER, the state of charge of the proposed battery is being utilized fully, as

shown in the figure above. Due to the high irradiance of the sun during the day, observing the red-

coloured area in the left screenshot, it illustrates that not only the network is getting supplied by the

PV system but also the battery remains fully charged. Whereas when the irradiance of the sun gets

lower and decreases to zero, the battery starts to function during these hours. On the right side of the

screenshot represents the 0-100% of the battery’s condition from month to month. The battery is

predicted to be operating at least 50-60% throughout the year, except for winter season where the

state of charge goes below 50%.

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Figure 26: Inverter and rectifier output from HOMER simulation

The condition of the inverters throughout the year remains around 200-300kW, as shown on the top

screenshot in the figure above. The inverter output is assumed to be the conversion of DC to AC from

the battery only since the PV system is already connected to the AC side based on the schematic

diagram shown in Figure 24. This also tells that the battery is discharging during the night time whereas

getting charged during the day time, as shown in the Rectifier Output screenshot. The energy that

charges the battery during the times shown in the figure above is from the solar generation.

7.3.2 All Components

Figure 27: Only diesel generator connected to AC side

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Unfortunately, under this scenario, HOMER was unable to simulate the required specifications. No

sensitivity case was provided. This is potentially due to the shortage of generation capacity since the

grid is not connected to the schematic.

Figure 28: Diesel generator and PV system connected on the AC side

Under this circumstance as well, the HOMER software was not able to simulate and provide a feasible

solution. Same reasons, as discussed previously.

Therefore for these particular scenarios, manual analysation by using the Microsoft Excel spreadsheet

is required.

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8 SUMMARY

8.1 FUTURE WORKS

It was identified within the research with the minimal assumptions that were made has affected the

accuracy of the performance and the related analysis. The following discussion summarises the areas

that require more attention, which would allow for further improvements for future project

advancements, greater network understanding, and also an increased analysis accuracy.

A further research towards the microgrid application of universities in Australia is needed to

strengthen not only the purpose of this project but to also acknowledge the potential existing

microgrid network in the universities. This would also lead to an outcome of encouraging other

institutions to promote reduction of carbon emissions by embracing the available renewable energy

resources.

For the PDCSO database, the TCE audit that was conducted in the early phases of the project needs to

be revisited and needs to be entered into the TCE database, so they are readily available within the

Microsoft Access for any future references that are related to Substation 13.

Proper training is required to utilize the HelioScope tool in terms of designing the proposed PV

systems. HelioScope is currently not a software that is being used as an educational tool at Murdoch

University. One needs a better understanding and grasp of the software from creating the base of the

structure of the targeted area to the electrical design of the buildings. The current proposed design’s

electrical works are inaccurate since the cable sizing and lengths are not correctly designed. To learn

this software towards a certain depth, a time investment is a critical requirement.

As a Renewable Systems designer, the PV system that is designed for this project needs to be revised

to meet with the AS/NZS (Australia & New Zealand) engineering standards. The associated buildings

from this thesis would not be able to support the weight of a 1.15MW size PV system. The placements

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of the PV panels should have some distance from panel to panel, including a distance from the edge

of the roofs. Each weight of the panels should be calculated and researched thoroughly to identify the

ability of the roof structure.

The shading conditions of the designed PV system should have a further investigation based on two

different seasons, summer and winter. The irradiance of the sun plays a significant role between these

two seasons and would affect the shaded PV panels in certain areas. Also, due to the climatic variations

between the two seasons, the potential dirt and dust that would cover the modules and may affect

the efficiency of the system.

Furthermore, the choice of inverters that are integrated within the PV systems needs to be discussed

in great detail with the PDCSO consultants to achieve reliable performance. The placements of the

inverters also require the attention from the perspectives of the associated technicians of SUB13. The

counts of the inverters can also be revisited and be identified if a one-sized inverter is better compared

to multiple central inverters. The choice of inverters’ manufacturers can also be compared to other

manufacturers in terms of the specifications, performances and its market prices.

The battery size that was proposed in the body of this report can be revisited if such changes occur in

the future such as prioritizing the diesel generator as the next in line backup source or the evolution

of PV system’s capacity if the proposed design is revised. Initially, the placement of the battery was

set to a particular place within the precinct. However, changes have been made during the journey of

this research. Therefore, further discussion and confirmation with the PDCSO consultants are highly

required once the size of the battery is confirmed.

The performance of the Microgrid application was entirely based on a worst-case scenario, which if

there was no supply from the grid for 24 hours and seven days. A high investigation of different

analysis can be made depending on a different scenario that can be considered into the Microgrid

flowchart. This would also affect the size of the battery required, the amount of excess energy from

the PV system, and the operation hours of the diesel generator.

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The economic analysis within this thesis report had excluded the price of the diesel fuel due to the

difficulties of specific areas such as insufficient information provided by the PDCSO in regards to the

existing diesel generator, the diesel price ranges back and forth depending on today’s economy and

also the duration of time to prioritize the diesel generator as a backup source. The schedule and

maintenance of the existing diesel generator are also uninformed. Therefore, further discussion with

the PDCSO consultants is highly recommended. This would also lead to a change of numbers in the

economic analysis in regards to the operation and maintenance, and the capital costs of each

component required.

A further investigation in regards to the economic analysis is required in the future, especially focusing

on the payback of the project. The PDCSO contains several confidential financial information which

has made this part of the research to be concluded into an assumption. For future reference, one shall

discuss with the consultants about the financial statement and ensures approval.

Further investigation on HOMER software is highly recommended. HOMER requires a better

understanding and better training with invested time to comprehend the settings of HOMER. Although

HOMER has been tested multiple times throughout the journey of this thesis, the author finds that

HOMER, by the end of the day, is an inaccurate software to use for this project’s analysis. A

methodology on using the HOMER software is also recommended for future references.

Lastly, for future works of this thesis project, necessary communication equipment needs to be

researched and implemented within this proposed Microgrid application to have the components to

communicate with one another. This could be applied when for example there is no sufficient energy

supply coming from the PV system; the battery would take over automatically to generate electricity,

and the diesel generator would help to meet the load demand when there is no grid supply. This will

also affect the SUB13’s single line network diagram if such high-level communication equipment is

included.

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8.2 CONCLUSIONS

This thesis describes the most important case of Microgrid that the university is recommended to use

the Microgrid system as an alternative way of self-energy generation based on no supply of electricity

from the main power grid. Having discussed in regards to the Murdoch University’s several power

failure events and putting such risks to different areas in the introductory part, this thesis has

discussed the potential generation of the different Microgrid components which it is also to meet the

network’s load demand.

HelioScope software was used to design a new PV system onto the roofs of the associated buildings

and has provided a potential capacity of the 1.15MW PV system. The online tool has also provided a

fine design of the network’s infrastructure to be able to fit as many numbers of modules as possible

in the ready-made space available on the associated roofs. The trees were considered into the design

only to identify the significant difference with the original design, and the result of this is only to expect

a 17% less PV generation.

Both diesel generator and battery play an important role in this project as they help to meet the load

demand during the off-peak hours if given the case of a grid supply failure. The option of choosing the

characteristics and model of the potential battery is suggested to lean towards an inexpensive energy

storage system for a quick return of investment for the project. Given the winter circumstance, an

increase of battery size would be recommended since there is a very low of solar irradiance at the

time. Otherwise, another solution to go with would be adding another diesel generator. However, the

existing diesel generator located in B245 is substantially aging. Therefore, to completely meet the load

demand during the winter, the most preferred choice is to upgrade the current diesel generator to a

larger kW size.

Other than that, the performance of the Microgrid components has been analysed and identified that

the principal strategy of the system is to have all three components, the PV system, the diesel

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generator, and the battery energy storage system, to generate electricity in parallel during the

occurrence of zero main supply from the grid.

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10 APPENDIX

10.1 APPENDIX A – HELIOSCOPE INDIVIDUAL DESIGNS

10.1.1 Non-Shaded Designs

Figure 29: From top left, B245, B235 and B240 designs without any shadings

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10.1.2 Shaded Designs

Figure 30: From top left, B245, B235, and B240 designs with shadings


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