report 2

DESIGN AND ANALYSIS OF ROOFTOP SOLAR
PHOTOVOLTAIC PLANT ON CAMPUS
REPORT FOR ENG 573 ENERGY SYSTEMS PROJECT
Submitted in partial fulfillment of requirements for the Master of Engineering Degree with a
concentration in Energy Systems in the Graduate College of the University of Illinois at
Urbana-Champaign
ABSTRACT
Growing energy use is putting pressure on the already limited fossil reserves and the rate of
energy consumption is increasing too. A portion of the energy being produced is used in
commercial and residential building for lighting, and for heating ventilation and cooling
(HVAC). The aim of the project described here is to suggest an alternative in the form of
installing the rooftop solar system on existing infrastructure and meeting a part of the buildings’
energy demand. The report involves the design of the solar systems on the roofs of six buildings
on campus. This work involves solar insolation calculation using the PvWatts software and
system design analysis on the PvSyst software. The economics of the scheme, the payback
amount, various subsidies and incentives given by the government are also discussed. Further,
different types of cost analysis on the basis of quality of panels including the cost of panels and
inverters are performed. Moreover, the various system cost involved in establishing the entire
system giving us a cost/kW from least to most expensive are worked out. Also, the use of solar
energy will reduce carbon footprint and cut greenhouse gas emissions.

Table of Contents Page No.
1. INTRODUCTION 1
2. LITERATURE REVIEW 2
3. ROOFTOP SOLAR SYSTEM 3
3.1 Motivation 4
3.2 Grid-tied System 5
3.3 Off-grid System 6
4. SYSTEM DESIGN 8
4.1 Use of Software 9
4.1.1 Software PV Watts-Description 10
4.1.2 Location for Weather Data 10
4.1.3 System Information 11
4.1.4 Output Report 12
4.1.5 Design Flexibility 14
4.2 Physical Design Calculations 15
4.2.1 Parameters. 15
4.2.2 Tilt Angle... 16
4.2.3 Arrangement of Panels 16
4.2.4 Temperature Effect 18
4.2.5 Design Procedure 19
4.2.6 Assumptions 19
5. ECONOMIC CONSIDERATIONS 20
6. LOSSES IN SYSTEM 23
7. POWER PLANT DESIGN 24
7.1 Physical Plant Services Building. 24
7.1.1 Design Constraints and Features 26
7.1.2 Economics 26
7.1.3 Layout 27

7.2 Activities and Recreation Center 29
7.2.2 Economics 30
7.2.3 Layout 32
7.3 Abbott Power Plant 33
7.3.2 Economics 35
7.3.3 Layout 35
7.4 Ikenberry Hall 36
7.4.2 Economics 38
7.4.3 Layout 39
7.5 Atkins Tennis Center 40
7.5.2 Economics 41
7.5.3 Layout 42
7.6 Art and Design Building 44
7.6.2 Economics 45
7.6.3 Layout 47
8. CONCLUSION 47
REFERENCES 48

List of Figures and Tables
Figure 1 Grid-tied System 5
Figure 2 Off-Grid System 6
Figure 3 Location Details 11
Figure 4 System Details 12
Figure 5(a) Final Report Generator. 13
Figure 5(b) Final Report Generator. 14
Figure 6 Design Flexibility 15
Figure 7 Panel Arrangements 17
Figure 8 Economic Calculation 22
Figure 9 Layout of Physical Plant Services Building 27
Figure 10 Layout of Activities and Recreation Center 33
Figure 11 Layout of Abbott Power Plant 35
Figure 12 Layout of Ikenberry Hall 40
Figure 13 Layout of Atkins Tennis Center 42
Figure 14 Layout of Art and Design Building 47
Table 1 Buildings –Area and Number of panels 18
Table 2 Economics of Physical Plant Services Building 28
Table 3 Economics of Activities and Recreation Center 32
Table 4 Economics of Abbott Power Plant 36
Table 5 Economics of Ikenberry Hall 39
Table 6 Economics of Atkins Tennis Center 43
Table 7 Economics of Art and Design 46

GLOSSARY
Photovoltaic Technology— The process of converting solar energy into electricity via flow of
electrons.
Photovoltaic Cell—A silicon wafer, which converts the solar irradiation to electricity.
Photovoltaic Module—An arrangement of photovoltaic cells enclosed within a protective glass
covering and mounted on an aluminum frame.
Solar Array—An arrangement of solar panels in a matrix configuration suitable to supply the
required voltage and current.
String Inverter—Direct current (DC) to alternating current (AC) conversion device used in
conjunction with a grid tied or off grid system.
Net Meter—An electrical appliance, which keeps track of incoming and outgoing electrical
current.
Combiner Box—A box used to combine multiple inputs of the solar array into one single
output.
MPPT— Maximum power point tracking (MPPT) is an inbuilt device in inverters used to track
the maximum power. MPPT tracks the maximum output of the system and applies the required
resistive load to give the maximum power.

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1. INTRODUCTION
The twentieth century witnessed innovations that made life more comfortable. The advent of
automobiles reduced the travel time between continents and cities. Communication systems have
networked people and brought them closer. The force that has made the entire above
breakthrough possible is electricity. It is essential for any community to survive, grow and
reproduce itself. The electric power has manifested itself in various forms like, in heating of
homes in cold areas and cooling in hot weather conditions. Electricity is also used for lighting
and drive electric vehicles.
However, there are certain limitations. Electricity, if produced, has to be utilized immediately or
else would be lost to the environment, so has to be transferred and generated continuously. Coal-
fired plants are the primary source of electrical energy but release thousands of tones of CO2,
CH4, and other greenhouse gases into the atmosphere. Automobiles also release harmful gases
into the air, enhancing global warming. Solar and wind power sources have emerged as the new
renewable and clean sources of energy. These sources are the fastest growing and are adopted
across the globe helping countries in meeting their goals of net zero carbon economies.
Companies and institutions around the world have been trying to reduce their global carbon
footprint and become energy independent. To achieve carbon neutrality, organizations are
exploring the rooftop solar system, recycling of waste material, purchasing carbon credits, smart
infrastructure practices, wastewater recycling, etc.
The ever-increasing demand for energy in developing economies, coupled with the desire to
improve the standard of living in the developed countries, has forced the world to find the new
sources of energy. Since the fossil fuels are limited in nature and polluting by character, the
importance of renewable and clean sources of energy has increased further.

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Conventional sources like nuclear, coal, hydro and natural gas are not sufficient to meet ever-
growing energy demands. Therefore, there is a need to go beyond these existing resources and
find an alternative in solar and wind energy, which can reduce the carbon footprint and cut the
greenhouse gas emissions. Rooftop solar plants are a step in that direction allowing consumers to
become producers, and give the freedom to go completely off grid or generate a part of their
energy consumption.
In the present project, the design of the solar systems on the roofs of six buildings on campus is
carried out. Solar insolation calculation using PvWatts and system design on PvSyst is
performed. The economics of the proposed systems are also discussed.
2. LITERATURE REVIEW
An extensive literature review was carried out to identify research gaps for rooftop solar systems.
A brief of each paper is furnished here:
Takebayashi et al. (2015) discussed the possibility of solar energy utilization based on the
relationship between urban morphology and solar radiation gain on building rooftops and wall
surfaces. Authors found that solar radiation on the roofs of all the buildings in Osaka was
reduced to about 86.3% when shadows of buildings in the neighborhood were considered.
Koo et al. (2016) developed an integrated multi-objective optimization model to find the optimal
solution for implementing the rooftop PV system. The study was conducted in six steps:
establishment of database, generation of the installation scenarios in the rooftop PV system,
energy simulation using the software program RETScreen, economic and environmental
assessment from the life cycle perspective, establishment of the iMOO process using a genetic
algorithm, and systemization of the iMOO model using a Microsoft-Excel-based VBA.

3
Plangklang et al. (2016) analyzed the power quality and energy yield of a large-scale PV rooftop
power plant in Samut Songkhram. The parameters used in the study were as follows: the root
mean square voltage, frequency, total voltage harmonic distortion, and voltage ripple. The
measured data showed that the power quality of this power plant passed the provincial electricity
authority regulations for its distribution network connecting system.
Singh and Banerjee (2015) proposed a methodology for estimating the rooftop solar photovoltaic
potential for a region. The method had been illustrated for the Indian city of Mumbai (18.98 N,
72.83 E). The effects of tilt angle on the plane-of-array insolation received had been studied to
make an optimum choice for the tilt angle.
Lang et al. (2016) presented a techno-economic analysis of PV self-consumption for four
different building types in Germany, Switzerland, and Austria. The authors found that, with self-
consumption. rooftop PV is attractive for many buildings in central Europe, even in the absence
of regulatory support. The authors also formulated recommendations for the implementation of
rooftop PV for business and policy makers.
Nicholls et al. (2015) evaluated the life cycle economic and environmental merit of rooftop PV
in Australia. The authors also developed life cycle cost and emission models. A sensitivity
analysis was performed on electricity price, feed-in tariff, battery price, and battery lifetime and
emission intensities. The results of the cost and emissions analyzes were collectively used to
estimate the cost of emissions mitigation through the use of rooftop PV for current and potential
future scenarios in Australia. The study also concluded that local load profile could have a
significant impact on payback times.
Tongsopit et al. (2016) analyzed business models and financing options for rooftop solar PV
investment in Thailand that had emerged during the period between 2013 and 2015. The business

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models, roof rental, solar leasing, and community solar were studied. The authors also analyzed
the drivers for their emergence, barriers to their success, and the risks from the business owners'
and consumers' viewpoints.
The next section provides the motivation and overview of the rooftop systems.
3. ROOFTOP SOLAR SYSTEM
In this section, grid-tied and off-grid solar rooftop systems are described. Before system
description, a brief motivation is provided in the next sub-section.
3.1 Motivation
In its sustainability report (Illinois Climate Action Plan 2015), the University of Illinois at
Urbana-Champaign campus aims to install rooftop solar projects across campus and become
carbon neutral by the end of 2050. The campus has also set fiscal year 2020 (FY 2020) as a
target to decrease its energy dependence on conventional sources by 30%. The plan is to produce
12.5 GWhr/year in the year 2020 and 25 GWhr/year by 2025 from solar installations on campus.
A rooftop solar project utilizes the vacant space on the roofs of buildings for installing a matrix
of solar panels and inverters in a configuration suitable to the needs of the buildings. The system
can be grid fed or off-grid based on the load and storage requirements. A grid-tied system is
designed to supply the energy generated back to the grid, via net metering and inverters, and
does not involve battery storage mechanism. On the other hand, the off-grid system requires
battery storage, charge controllers, and inverters that work independently of the grid.

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3.2 Grid-tied System
In a grid-tied system, the solar energy is transformed into electricity and fed into the grid.
Refer to Fig. 1, for a diagram of a grid-tied system.
Figure 1: Grid-tied System
The various steps involved in the design of a grid-tied system are as follows:
 The panel and the inverter are selected according to the load, amperage, and system voltage
requirements.
 The solar panels are arranged in series and parallel configuration and fed to the grid
compatible inverter.
 The output of the inverter is fed into the net metering box via alternating current (AC)
disconnect and then fed to the grid.
Utility
Grid
Net
Meter
Load
Main
Panel
Solar
Inverter
Solar
Array
DC
AC
AC
AC
AC

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 The net meter keeps track of the power sourced and power fed to the grid.
 The consumer is charged according to the net energy produced supplied from the grid.
3.3 Off-grid System
In the off-grid system, the solar power obtained through PV system is directly used for
residential/commercial applications. Solar panels convert solar energy into direct current (DC)
electricity that is further transformed by an inverter into AC electricity for different applications.
A charge controller regulates the flow of solar electricity into the batteries and deep-cycle
batteries stores solar power for later use. Refer to Fig. 2 for a diagram of an off-grid system
Figure 2: Off-grid System
Generator
Battery
Bank
House
Inverter
Charge
Controller
Solar
Array
DC
DC
DC
AC
DC

7
The various steps involved in the design of off-grid systems are as follows:
i. Load calculation:
a) The AC load of the system is calculated by wattage and hours of operation.
ii. Electronics component selection
a) The total wattage as calculated is divided by the efficiency of the inverter to find the VA
requirement of the inverter.
b) The energy from step i (a) as calculated is divided by the efficiency of the inverter to find the
total energy demand.
c) The system voltage is usually assumed to be 24 or 48 V.
d) The wattage from step i (a) is divided by system voltage to get the system maximum current.
iii. Battery Sizing:
a) The autonomy or the number of days system has to keep running in case of power failure is
assumed, e.g., one day.
b) The total energy from ii (b) is multiplied by the autonomy day as per iii (a) and divided by
the system voltage as per ii (c) to find the battery ampere-hour capacity.
c) The ampere-hour capacity is divided by the depth of discharge usually 50% to optimize our
system.
iv. Solar Photovoltaic Sizing
a) The energy calculated without autonomy days is divided by the number of sunshine hours in
the region to find the wattage of the panels.
b) The wattage is divided by the power output of a panel to determine the number of panels.

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4. SYSTEM DESIGN
This section deals with the various aspects of the design of the system. Rooftop solar PV stations
have panels mounted on the roof with mounting systems, cables, and inverters. Their sizes are
usually in kW, unlike in MW range for ground-mounted systems. Rooftop solar panels are often
installed to meet a part of energy demand of the building and do not completely offset the energy
demand. There are various aspects of the system design, e.g., tilt angle, roof inclination, roof
aspect. These types of systems may be designed off-grid or grid tied depending on the end use.
There are two different approaches to system design.
Size (kW) = array area (m²) × 1 kW/m² × module efficiency
or
Size (kW) = module nameplate size (W) × number of modules ÷ 1,000 W/kW
The important parameter issues to consider while system designing are:
o Selection of the right panels, i.e. the technology used, crystalline or thin film. The
efficiency of the panel affects the output of the system.
o The array type of the panel, i.e. whether each module in the design of the array is
fixed type or movable that affects the overall output of the system. In a tracking
mechanism, the panels might be subjected to shading which has to be avoided.
Therefore, the south facing panels with fixed type array are used.
o In system design, several losses are considered. The losses are classified as
efficiency losses of the inverter, losses due to soiling, and loss due to snow and
shading, wiring heat losses, and other types of losses.
o The tilt angle of the panel is the angle from the horizontal of the panel. It is 0° for
horizontal configuration and 90° for vertical. The tilt angle is set at less than the

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latitude of the location to maximize the output, since small tilt angles favor peak
production in the summer months. However, the higher tilt angles support low
irradiance conditions during the winter period. Having tilt angle greater than
latitude favors energy production in the winter, while a small tilt favors energy
production in summer.
o The azimuth angle is the angle measured clockwise from the north. It is 0° for
north and 180° for the South. The default value for azimuth angle is 180° for
south facing locations in the northern hemisphere whereas it is 0° for north facing
areas in the southern hemisphere.
o The economics of the system, i.e. rate of interest, the capital cost, payback period,
etc. are considered. The price also depends on the local cost of the utility and
additional expenses in connecting it to the grid.
o The site selection for the panel is also considered in the design. The performance
of the system depends on the latitude and the longitude of the location as the local
weather pattern; irradiation and wind speed influence the output.
The system is designed either through the use of software such as PvSyst, PvWatts, Solmetric, or
by direct mathematical modeling.

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4.1 Use of Software
In this section, the system is designed using PvWatts-software.
4.1.1 Software PvWatts—Description
PvWatts is an interactive tool developed by National Renewable Energy Laboratory (NREL).
The tool helps in analyzing the potential and cost of energy produced in a location throughout the
world. The location is fed into the software and, based on the meteorological data, the number of
sunshine hours is calculated for each month.
The system sizing and input losses are also fed into the software. Depending upon the type of
panel, tracking features, system losses and sizing of the panel, an estimate of the number of units
produced annually is calculated. Total cost is determined by multiplying cost per unit times the
number of units.
However, the tool just described gives only an estimation of the units and energy cost. Actual
data may vary depending on the features of the actual setup and cost.
4.1.2 Location for Weather Data
The location details are required for the weather data. The data for the selected location is fed
into the software. See to Fig. 3 for more information.

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4.1.3 System Information
Refer to Fig. 4 for system details. These inputs are required to run the simulation.
Figure 4: System Details

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4.1.4 Output Report
The tool gives an estimation of the number of units produced, and the total cost is calculated by
multiplying it with the cost of each unit. Refer to Fig. 5(a) and (b), for final report generator.
Output.
Figure 5(a): Final Report Generator

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Figure 5(b): Final Report Generator
4.1.5 Design Flexibility

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This feature of the software helps in customizing the design as per the requirement. Refer to
Fig. 6 for an example relevant to design flexibility.
Figure 6: Design Flexibility

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4.2 Physical DesignCalculations
In this subsection, aspects related to the physical design are described.
4.2.1 Parameters
Various features considered for design are listed here:
 The location where the plant has to be setup.
 The annual solar irradiation data, wind speed pattern and other projections on the surface,
which may affect the performance of the panel.
 The rated output of the system.
 The number of panels and inverters.
 The arrangement of panels, series or/and parallel to optimize to the rated input to the
inverter.
 The connection of the panels to the DC combiner box before being fed into the inverter to
reduce the number of wires and associated wiring losses.
4.2.2 Tilt Angle
The latitude and longitude of Champaign Illinois are 40.1150° N and 88.2728° W respectively.
The tilt angle is calculated for latitude between 25° and 50° by the following formula
(Charles 2015):
0
0 0
0 0
*0.87 25
an *0.93 21 25 50
*0.875 19.2 25 50 int
latitude if latitude
Tilt gle latitude if latitude in summer
latitude if latitude in w er


   
   

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4.2.3 Arrangement of Panels
The panels are arranged to avoid shading losses. This constraint requires a larger area than the if
for a horizontal orientation. There are two possible orientations to prevent shading loss, portrait
and landscape. Refer to Fig. 7 for the arrangements of the panels.
Portrait Landscape
Figure 7: Panel Arrangements
In case of portrait arrangement, the area is calculated using the following relation
(EATON 2015):
sin( )*
sin
L
D  

 
The area for landscape arrangement is given by the following expression (EATON 2015):
sin( )*
sin
W
D  

 
Shading
Shading

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where; D—distance of shading, α —latitude of installation, θ— angle of tilt,
L—length of panel W—width of panel n—no of panels from calculation
The portrait mode is used to avoid shading loss. The minimum spacing, in this case, is 60 cm.
The area thus required for the panels is equal to n=A/(W*D).
However, the area could be altered if the number of panels in series in a string is varied.
The details of calculated roof area, the solar roof area and the number of panels is given in
Table 1.
Table 1: Building wise –Area and number of panels
Building Roof area Solar roof area Number of panels
1. Physical plant services building 12000 m2
4004 m2
1740
2. Activities and recreation center 11000 m2
3715 m2
1615
3. Abbott power plant 4000 m2
1575 m2
829
4. Ikenberry hall 5800 m2
2283 m2
1200
5. Atkins tennis center 5200 m2
2047 m2
1052
6. Art and design building 1500 m2
591 m2
302
4.2.4 Temperature Effect
The temperature of the panel affects its performance. The impact of temperature on the PV panel
is significant, and there is a substantial drop in performance even for the 10C rise in temperature.
The current in the panel increases with the increase in temperature due to the decrease in the
band gap of the material that leads to more mobility for the electrons. The voltage of the panel
decreases with the rise in temperature because the open circuit voltage is dependent on the
current. Mounting the panels few inches above the substrate to allow the flow of air reduces the

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effect of heat on the solar panel. Further, to reduce heat absorption panels are constructed with
light colored materials. Therefore, the system is designed keeping in mind the temperature effect
on the panel.
The highest and lowest temperature ever recorded in Illinois was 47 °C, and -38° C respectively.
(Temperature profile 2015)
4.2.5 Design Procedure
The following steps are followed in designing of rooftop system
 The panel is selected based on its rated output.
 The number of panels is calculated by dividing the rated power output of the system to
the power output of a panel.
 Calculate the string voltage by multiplying the number of panels in the string and Voc of
the panel.
 The string voltage is taken as the maximum input voltage of the inverter
 The number of strings is determined by dividing the total number of panels to the panels
in a single string.
 The inverter input current divided by the string current gives the number of parallel
connections.
 The strings are then arranged in parallel to provide the maximum input current from the
inverter.
 The parallel connections are fed into the combiner box to give one single output wire to
the inverter input.

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 The system voltage is adjusted to the inverter tracking voltage if it is equipped with a
maximum power point tracker (MPPT) tracker.
4.2.6 Assumptions
The following assumptions are made for design calculations.
i. The system design calculations are based on the panel efficiency of 15%.
ii. The arrays are fixed type with the number tracking mechanism.
iii. The system losses due to soiling, shading, mismatch and wiring are 2%, 3%, 2% and 2%
respectively.
iv. The system losses due to connections and the degradation of panels are 0.5% for each
case.
v. The system losses due to maintenance and nameplate rating are 3% and 1% respectively.
vi. The tilt angle for the panel is 20°.
vii. The azimuth angle for the system is 180°, i.e. south facing panels.
5. ECONOMIC CONSIDERATIONS
In this section, economic aspects such as capital cost, energy cost, energy payback time, and tax
incentives are discussed. Economics are important in design a PV system. The biggest inhibitor
restricting the full-scale adoption of solar panels as a primary power generation option is the
cost. The initial cost along with a higher operation and maintenance every year limits the use of

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the system on a large scale. However, government support along with various tax incentives is
improving the extent and adaptability of the solar system.
The various types of economics are:
Capital cost—The capital cost of the system includes the costs of PV panels, inverters, wiring,
DC combiner box, and net metering. The capital cost also includes the labor and installation cost
of the system without factoring in the incentives and subsidies.
Energy cost—The energy cost is variable and differs from region to region and is directly
proportional to the number of units of electricity produced. The systems total electrical output for
the year multiplied by the retail electricity price assuming a degradation of 0.5 % per annum with
no increase in the price.
Operation and maintenance—Amount of money spent every year to keep the system at the
optimal operation level. The operation and maintenance cost also include the cost of replacement
of some of the panels or change of wiring or some additional payment to the plant operator, and
these are variable.
Tax Incentives—Reduction in the capital cost of the system provided in the form of incentives
by the government. The incentives are in the form of tax rebates and subsidies on the
components, material, etc.
Others—Additionally, there are other incentives such as; tax-free income or investment credits
given by the government that varies country to country.
Energy payback time—It is the time to generate the power to pay back the initial investment or
the energy consumed in producing the panel. The energy payback is an important parameter

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considered in system financial calculations. It is desired to have a shorter payback period for
commercial operations.
Interest rates—Interest rates on the loan taken to set up a project vary depending on
macroeconomic conditions and on the duration and estimated risk associated with the loan.
Depreciation cost—The cost incurred due to the depreciation in the value of the material and the
degradation of the panels. The depreciation cost is considered to evaluate the system financial
payback period.
Refer Fig. 8 for economic calculations.
Figure 8: Economic Calculation

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6. LOSSES IN SYSTEM
The many losses in the system design are discussed in this section.
Shading loss: It affects the performance of the system drastically. The PV panel, if subjected to
any form of shading, can lose as much 50–90% of its output. This is due to shadow effects of a
nearby tree or building on the surface of the panel.
Soiling loss: This is the loss where the panel, if exposed to dust snow or any other form of
external environmental disturbance, may lose its output due to irregular or less of incident solar
radiation on the surface of the panel. Such loss varies with the region and weather pattern. It is
more in areas of high pollution and occasional rains. In cold regions, it may be due to
accumulation of snow on the panel surface.
Recombination losses: These losses occur at the molecular level due to the recombination of the
electrons and holes in the p-n junction layer. The holes and electrons do not recombine perfectly,
and the carrier concentration varies due to impurities in the n-type or p-type layers of the
semiconductor that leads to the losses in the system.
Heating losses: This kind of loss occurs in the system wiring due to the excess current fed into
the circuitry. The wires in the design are selected by the maximum current in the system. If the
current is more than the designed value, there are resistive losses in the circuit due to the heating
effect.
Efficiency losses: These losses are usually due to mismatch of the inverter and battery with the
PV panel. The selection of the right inverter and panel for the solar plant design minimizes such
losses.

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Degradation losses: The panels designed for 25 years may lose their performance after few
years of operation. The aging of the panels due to intrinsic fall of the performance of the
semiconductor material, erratic solar irradiance and weathering hampers the performance.
Nameplate rating loss: The loss in the system due to error in the manufacturers rating. The
actual output of the panel as specified by the manufacturer may differ from the field-testing that
has to be accounted in design.
Availability/Maintenance losses: The panels have to be inspected and maintained periodically
that requires removal from the system. This adds system downtime and reduces availability. In
small kW size plants, the losses may not be so dominant, but as the size increases the
contribution to total system loss increases.
7. POWER PLANT DESIGN
In this section, the design of the power plant is described for six different buildings on the
university campus.
7.1 Physical Plant Services Building
The physical plant services building provide the essential services like maintenance,
construction, safety and compliance. The building houses the university facilities and services
office, which provides administrative as well as information technology services to all the allied
departments and faculties on the campus. This building is also responsible for retrofitting and up
gradation of existing infrastructure and introducing the new technologies for efficient working of
campus facilities. The design of the power plant for the physical plant services building is
described next.

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Panel: Sunpower: X-21-345 (Sunpower 2015)
Power = 345 W; Voc = 68.2 V; Isc = 6.39 A; System voltage = 1000 V
Max. current=20 A; Voltage coefficient = -167.4 mV/C; Current coefficient=3.5 mA/C
Inverter: ABB PVI 12.5 TL (ABB Small Wind Inverters 2015)
Tracking voltage=360–750 V; Input range=130–850 V; Current=36 A; Isc=6.39 A
Maximum current=45 A; Maximum power=12500 W; Number of input=1
Rated output of system= 600 kW
Number of panel’s
600 1000
1740
345
X
 ; panels
Inverter voltage =750 V
Number of panels in a string 11
Inverter input voltage
Voltage of one panel
  panels
Number of strings 158
Total number of panels
Number of panels in strings
  strings
Inverter input current = 36 A; current in string = 6.39 A
Parallel strings 5
 
DC combiner Box 5:1—5 inputs and 1 output
Number of DC combiner box 32
Number of strings
DC combiner ratio
 
Number of output wires =32; number of input in inverter = 1

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Number of inverter 32
Number of output wires
Number of input to inverter
 
7.1.1 Design Constraints and Features
The following constraints are considered for the design
 In series, the current remains the same for string while the voltage is added.
 In parallel, the voltage of string remains the same while the current is added.
 The string voltage and current should not exceed the inverter input voltage and
current respectively.
Also, the system considered is equipped with Maximum power point tracker (MPPT) tracking. It
is highly reliable and stable but expensive.
7.1.2 Economics
The following data is used for the economics of physical plant services building.
Panel cost=2.64$/watt; Inverter cost=0.28$/watt (RES Supply 2015); Installation
cost=0.40$/watt; wiring, mounting frame and combiner box=0.50$/watt;
miscellaneous=0.03$/watt;
Total cost=3.85$/watt.
Solar PV Power Plant
Capacity of solar power plant considered =600 kW; Annual solar insolation = 4.74 kWh/m2/day;
Annual solar units generated=827335 kWh/year; Annual power degradation=0.5%;
Capital cost =3.85$/watt; Total cost=$2,310,000.

27
State Electricity Supply
Average electricity price per unit=0.05$/kWh; Annual escalation=7.5%
Refer, Table 2, for results of the economic measures of the physical plant services building.
7.1.3 Layout
Refer, Fig. 9 for the schematic diagram of the physical plant services building.
Figure 9: Layout of Physical Plant Services Building
Solar
Array
5:1
Combiner
Box
Inverter

28
Table 2: Economics of Physical Plant Services Building
Years Grid Electricity ($/Kwh)Energy generation (Mwh) Yearly Revenue (K$)
1 0.05 827 41
2 0.05 823 44
3 0.06 819 47
4 0.06 815 51
5 0.07 811 54
6 0.07 807 58
7 0.08 803 62
8 0.08 799 66
9 0.09 795 71
10 0.10 791 76
11 0.10 787 81
12 0.11 783 87
13 0.12 779 93
14 0.13 775 99
15 0.14 771 106
16 0.15 767 114
17 0.16 764 121
18 0.17 760 130
19 0.18 756 139
20 0.20 752 149
21 0.21 748 159
22 0.23 745 170
23 0.25 741 182
24 0.26 737 195
25 0.28 734 208
Total 19489 2602

29
7.2 Activities and Recreation Center
The activities and recreation center (ARC), a sparkling 340,000 square feet complex, is one of
the largest on-campus recreation centers in the entire USA. It has many amenities, including a
sauna, swimming pools, racquetball courts, and basketball courts. The ARC, with lots of
machines and gymnasiums also houses an indoor auditorium all for the benefit of the student and
faculty alike. The building with its unique design is a landmark in University of Illinois at
Urbana-Champaign and also has a courtside café to complement fitness enthusiasm. The design
of the power plant for the activities and recreation center is described next.
Panel: Sunpower: X-21-345 (Sunpower 2015)
Power=345 W; Voc=68.2 V; Isc=6.39 A; System voltage=1000 V
Max. current=20 A; Voltage coefficient=-167.4 mV/C; Current coefficient=3.5 mA/C
Inverter: ABB PVI 12.5 TL (ABB Small Wind Inverters 2015)
Tracking voltage=360–750 V; Input range=130–850 V; Current=36 A
Maximum current=45 A; Maximum power=12500 W; Number of input=1
Number of panel’s
557 1000
1615
345
X
 ; panels
  panels
  strings
Inverter input current = 36 A; current in string = 6.39 A

30
Parallel strings 5
 
DC combiner Box 5:1 —5 inputs and 1 output
Number of strings
DC combiner ratio
 
Number of output wires =30; number of input in inverter = 1
 
 The string voltage and current should not exceed the Inverter input voltage and
Also, the system considered is equipped with MPPT tracking. It is highly reliable and stable but
expensive.
7.2.2 Economics
The following data is used for the economics of the activities and recreation center.
Panel cost=2.64$/watt; Inverter cost=0.28$/watt (RES Supply 2015); Installation
cost=0.40$/watt; wiring, Mounting frame and combiner box=0.50$/watt;
Miscellaneous=0.03$/watt;
Total cost=3.85$/watt.

31
Solar PV power plant
Capacity of solar power plant considered =557 kW; Annual solar insolation=4.74 kWh/M2/day;
Annual solar units generated=768043 kWh/year; Annual power degradation=0.5%; Capital cost
=3.85$/watt; Total Cost=2,144,450
State electricity supply
Refer, Table 3, for results of the economic measures of the activities and recreation center.
7.2.3 Layout
Refer to Fig. 10 for a schematic diagram of the activities and recreation center.
Figure 10: Layout of Activities and Recreation Center
Solar
Array
5:1
Combiner
Box
Inverter

32
Table 3: Economics of Activities and Recreation Center
Years Grid Electricity($/kwh) Energy generation (Mwh) Yearly Revenue(K$)
1 0.05 768 38
2 0.05 764 41
3 0.06 760 44
4 0.06 757 47
5 0.07 753 50
6 0.07 749 54
7 0.08 745 58
8 0.08 742 62
9 0.09 738 66
10 0.10 734 70
11 0.10 730 75
12 0.11 727 81
13 0.12 723 86
14 0.13 720 92
15 0.14 716 99
16 0.15 712 105
17 0.16 709 113
18 0.17 705 121
19 0.18 702 129
20 0.20 698 138
21 0.21 695 148
22 0.23 691 158
23 0.25 688 169
24 0.26 684 181
25 0.28 681 193
Total 18092 2416

33
7.3 Abbott Power Plant
The Abbott power plant is a co-generation facility producing steam for heating and cooling
campus buildings and generating electricity to be supplied to the campus while maintaining a
balance between safety, compliance, and reliability. The building was constructed in 1941, right
adjacent to the main line of railroad to allow for quick delivery of coal. The Abbott plant located
on the south side of campus has undergone numerous additions and alterations namely in coal
boilers, desulfurization scrubbers, etc. The design of the power plant for the Abbott power plant
is described next.
Panel: Sharp NU-Q 245 W4 (SHARP 2015)
Power = 245 W; Voc=37.6 V; Isc=8.75 A; System voltage=600 V; Max. current=15 A
Voltage coefficient=-0.351% mV/C; Current coefficient=0.053 % mA/C
Inverter: Chint CPS SC 14 KTL -DOUS -208 (Chint Power Systems America 2015)
Tracking voltage = 300–540 V; input voltage = 180–580 V;
Input current = 50 A (25 A per MPPT); Maximum DC input voltage = 600 V
Maximum DC input current = 90 A (45 A per MPPT); Number of inputs = 2;
Number of MPPT tracker =2; Rated output of system= 203 kW
Number of Panels 203 1000
829
245
X
 ; panels
  panels

34
  strings
Inverter Input Current = 25 A; Current in String = 8.75 A
Parallel strings 2
 
DC combiner Box 2:1 —2 Input and 1 output
Number of DC combiner Box 32
Number of strings
DC combiner ratio
 
Number of output wires =32; Number of input in inverter = 2
Number of Inverter 16
 
Also, the system considered is equipped with MPPT tracking. It is more reliable and stable but
moderately expensive.

35
7.3.2 Economics
The following data is used for the economics of the Abbott power plant.
Panel cost=1.60$/watt; Inverter cost=0.19$/watt; Installation cost=0.40$/watt; Wiring, Mounting
frame and combiner box=0.50$/watt; Miscellaneous=0.03$/watt; Total cost=2.72$/watt
Solar PV power plant
Capacity of Solar power plant considered =203 kW; Annual solar insolation=4.74 kWh/M2/day
Annual Solar units generated=279915 kWh/year; Annual Power Degradation=0.5%; Capital
Cost =2.72$/watt; Total Cost=552,160
State electricity supply
Average electricity price per unit=0.05$/kWh; Annual Escalation=7.5%
Refer, Table 4, for results of the economic measures of the Abbott power plant.
7.3.3 Layout
Refer to Fig. 11 for a schematic diagram of the Abbott Power Plant
Figure 11: Layout of Abbott Power Plant
Solar
Array
2:1
Combiner
Box
Inverter

36
Table 4: Economics of Abbott Power Plant
Years State Tariff($/kwh) Energy generation (Mwh) Yearly Revenue(K$)
1 0.05 280 14
2 0.05 279 15
3 0.06 277 16
4 0.06 276 17
5 0.07 274 18
6 0.07 273 20
7 0.08 272 21
8 0.08 270 22
9 0.09 269 24
10 0.10 268 26
11 0.10 266 27
12 0.11 265 29
13 0.12 264 31
14 0.13 262 34
15 0.14 261 36
16 0.15 260 38
17 0.16 258 41
18 0.17 257 44
19 0.18 256 47
20 0.20 254 50
21 0.21 253 54
22 0.23 252 58
23 0.25 251 62
24 0.26 249 66
25 0.28 248 70
Total 6345 880

37
7.4 Ikenberry Hall
Ikenberry Hall houses four halls, Barton, Lundgren, Hopkins, Weston and a recent addition
Nugent. Ikenberry Hall provides housing for undergraduate students and also accommodates
in-house dinning services. The hall is also a recreation center for students with conference
rooms, kitchens, computer rooms, conference rooms, etc. It is home to students coming from
different communities. The design of the power plant for the Ikenberry hall is described next.
Power=245 W; Voc=37.6 V; Isc=8.75 A; System voltage=600 V; Max current=15 A
Voltage coefficient=-0.351% mV/C; Current coefficient=0.053% mA/C
Inverter: Chint CPS SC 14 KTL -DOUS -208 (Chint Power Systems America 2015)
Tracking voltage=300–540 V; Input voltage=180–580 V;
Input current= 50 A (25 A per MPPT); Maximum DC input voltage=600 V
Maximum DC input current= 90 A (45 A per MPPT); Number of inputs=2
Number of MPPT tracker=2; Rated output of System= 294 kW
Number of Panels
294 1000
1200
245
X
 ; panels
Inverter Voltage =580 V
  panels
Number of Strings 100
  strings
Inverter Input Current = 25 A; Current in string = 8.75 A
Parallel strings 2
 

38
DC combiner Box 2:1—2 Input and 1 output
Number of strings
DC combiner ratio
 
 
Also, the system considered is equipped with MPPT tracking. It is more reliable and stable but
relatively expensive.
7.4.2 Economics
The following data is used for the economics of Ikenberry Hall.
Panel cost=1.60$/watt; Inverter cost=0.19$/watt; Installation cost=0.40$/watt; Wiring, mounting
frame and combiner box=0.50$/watt; Miscellaneous=0.03$/watt
Total cost=2.72$/watt
Capacity of solar power plant considered =294 kW; Annual solar insolation=4.74 kWh/M2/day
Annual solar units generated=405394 kWh/year; Annual power degradation=0.5%

39
Capital cost =2.72$/watt; Total cost=799,680
Refer to Table 5 for results of the economic measures of the Ikenberry hall.
7.4.3 Layout
Refer to Fig. 12 for a schematic diagram of the Ikenberry Hall
Figure 12: Layout of Ikenberry Hall
Solar
Array
2:1
Combiner
Box
Inverter

40
Table 5: Economics of Ikenberry Hal
Years Grid Electricity($/kwh) Energy generation (Mwh) Yearly Revenue (K$)
1 0.05 405 20
2 0.05 403 22
3 0.06 401 23
4 0.06 399 25
5 0.07 397 27
6 0.07 395 28
7 0.08 393 30
8 0.08 391 32
9 0.09 389 35
10 0.10 388 37
11 0.10 386 40
12 0.11 384 43
13 0.12 382 45
14 0.13 380 49
15 0.14 378 52
16 0.15 376 56
17 0.16 374 60
18 0.17 372 64
19 0.18 370 68
20 0.20 369 73
21 0.21 367 78
22 0.23 365 83
23 0.25 363 89
24 0.26 361 95
25 0.28 359 102
Total 9549 1275

41
7.5 Atkins Tennis Center
The Atkins tennis center was opened in 1991 and is a home to both men and women tennis at
UIUC. It has six indoor courts and 20 outdoor courts and host’s elite tournaments like JSM
Challenger and some junior level tournaments. The compound is called A SKhan Outdoor
Tennis Complex and houses a pro shop and court times for general public use. It can hold 3800
people. The design of the power plant for the Atkins tennis center is described next.
Inverter: Solar Edge SE 5000 A-US
Tracking Voltage — Not applicable; Input voltage=500 V; Input current= 45 A
Maximum DC input voltage=500 V; Number of inputs=1; Number of MPPT tracker=0
Rated output of system= 265 kW;
Number of panels panels
inverter input voltage
voltage of one panel
  panels
Number of strings =
= 98strings
Inverter input current = 45 A; Current in string = 8.83 A

42
Parallel strings 4
 
Number of strings
DC combiner ratio
 
 
 The string voltage and current should not exceed the Inverter input voltage and current
respectively.
In addition, the system considered is not equipped with MPPT tracking. Although, it is very
cheap but it is neither highly reliable nor stable.
7.5.2 Economics
The following data is used for the economics of Atkins tennis center.
Panel cost=0.84$/watt (Webo Solar 2015); Inverter cost=0.26$/watt (Alternate Energy Store Inc.
2015); Installation cost=0.40$/watt; Wiring, mounting frame and combiner box=0.40$/watt;
Miscellaneous=0.03$/watt; Total cost=1.93$/watt
Capacity of solar power plant considered =265 kW; Annual solar insolation=4.74 kWh/M2/day

43
Annual solar units generated=365406 kWh/year; Annual power degradation=0.5%; Capital cost
=1.93$/watt; Total cost=511450
Refer to Table 6 for results of the economic measures of the Atkins tennis center.
7.5.3 Layout
Refer, to Fig. 13 for the schematic diagram of Atkins tennis center.
Figure 13: Layout of Atkins Tennis Center
Solar
Array
5:1
Combiner
Box
Inverter

44
Table 6: Economics of Atkins Tennis Center
Years Grid Electricity($/Kwh) Energy generation (Mwh)Yearly Revenue (K$)
1 0.05 365 18
2 0.05 364 20
3 0.06 362 21
4 0.06 360 22
5 0.07 358 24
6 0.07 356 26
7 0.08 355 27
8 0.08 353 29
9 0.09 351 31
10 0.10 349 33
11 0.10 348 36
12 0.11 346 38
13 0.12 344 41
14 0.13 342 44
15 0.14 341 47
16 0.15 339 50
17 0.16 337 54
18 0.17 336 57
19 0.18 334 61
20 0.20 332 66
21 0.21 331 70
22 0.23 329 75
23 0.25 327 80
24 0.26 326 86
25 0.28 324 92
Total 8607 1149

45
7.6 Art and DesignBuilding
A multidisciplinary art school at University of Illinois at Urbana-Champaign houses academic
units that include the School of Architecture and Design as well as dance and ceramics. The
design of the power plant for the art and design building is described next.
Inverter: Solar Edge SE 5000 A-US
Tracking voltage —Not applicable; Input voltage=500 V; Input current= 45 A
Maximum DC input voltage=500 V; Number of Inputs=1; Number of MPPT tracker=0
Number of panel panels
Number of panel in a string 11
inverter input voltage
voltage of one panel
  panels
  strings
Inverter input current = 45 A; Current in String = 8.83 A
Parallel strings 4
 

46
Number of strings
DC combiner ratio
 
 
Also, the system considered is not equipped with MPPT tracking. Although, it is very cheap but
it is neither highly reliable nor stable.
7.6.2 Economics
The following data is used for the economics of the Art and Design Building.
Panel cost=0.84$/watt (Webo Solar 2015); Inverter cost=0.26$/watt (Alternate Energy Store Inc.
2015); Installation cost=0.40$/watt;
Wiring, Mounting frame and combiner box=0.40$/watt; Miscellaneous=0.03$/watt
Total cost=1.93$/watt
Capacity of solar power plant considered =76 kW; annual solar insolation=4.74 kWh/M2/day

47
Annual solar units generated=104795 kWh/year; Annual power degradation=0.5%
Capital cost =1.93$/watt; Total cost=511450
Refer, Table 7, for results of the economic measures of the Art and design building
7.6.3 Layout
Refer, Fig. 14 for the schematic diagram of art and design Building
Figure 14: Layout of Art and Design Building
Solar
Array
5:1
Combiner
Box
Inverter

48
Table 7: Economics of Art and Design Building
Years Grid Electricity($/Kwh) Energy generation (Mwh) Yearly Revenue (K$)
1 0.05 105 5
2 0.05 104 6
3 0.06 104 6
4 0.06 103 6
5 0.07 103 7
6 0.07 102 7
7 0.08 102 8
8 0.08 101 8
9 0.09 101 9
10 0.10 100 10
11 0.10 100 10
12 0.11 99 11
13 0.12 99 12
14 0.13 98 13
15 0.14 98 13
16 0.15 97 14
17 0.16 97 15
18 0.17 96 16
19 0.18 96 18
20 0.20 95 19
21 0.21 95 20
22 0.23 94 22
23 0.25 94 23
24 0.26 93 25
25 0.28 93 26
Total 2469 330

49
8. CONCLUSION
Solar energy provides a better option as it is a clean, green, and reliable source. Solar systems
have become more affordable and flexible, since they can be installed anywhere given adequate
sunlight. Additionally, the use of the solar energy helps limit the global warming effects such as
rising carbon content in the atmosphere, an increase in sea level, destruction of the environment
and pollution of the air.
Rooftop solar systems are also beneficial in cutting the carbon footprint of a building while also
meeting a certain portion of the building’s energy requirement. If given the required area and
sunshine, a rooftop solar system can substantially reduce the green house gas emissions of any
commercial or residential house and also meet a portion of the future energy demand.

50
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