Design and analysis of an isolated PV system for a house in Libya

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Design and analysis of an isolated PV system for
a house in Libya
Youssef Dabas,
M. Tariq Iqbal.
Faculty of Engineering & Applied Science, Memorial University, Canada
yhmdabas@mun.ca, tariq@mun.ca
Abstract— In this research, the annual energy consumption
of a private house in Libya is presented. Using the load data,
the design of a photovoltaic system (PV) has been done using
HOMER Pro. The designed system contains 26 PV panels of
330W each, 32, 12V, batteries and a 5.61kW inverter. The
system analysis illustrates that such a system can meet all load
requirements of a private house in Libya. MATLAB/Simulink
has been used to simulate the dynamic model of the designed
system. The simulation results show that the system can
provide a stable voltage and frequency for the proposed load
and its variations.
Keywords—solar energy, photovoltaic, HOMER Pro.
I. INTRODUCTION
A. Solar Energy in Libya
Libya is a North Africa country that covers a total area of
1,750,000 Km². It relies heavily on oil and natural gas to
produce electric power. These resources are nonrenewable
and limited[1]. However, the electric energy demand
increases as a result of growth in the industries and the
population of Libya, which leads to more fuel consumption
and more investments in energy grid from power stations,
transmission lines, and substations. Also, environmental
concern is one of the important issues these days. That makes
progress made in the areas of renewable energy technologies
that are opening the doors for an alternative source highly
pertinent. Achieving this is relatively enhanced since most of
the territories of Libya in the Sahara desert, which are great
sources of solar radiation with a daily average direct normal
irradiation ranging between 8.1 kWh/m2/day in the southern
part and 7.1 kWh/m²/day in the western part with a sunshine
duration hours more than 3500 for each year[2].
An analysis of the opportunities, challenges, and
possibilities of renewable energy in Libya was presented[1].
The study concluded that this is an achievable objective.
Given the challenges with conventional ways of power
generation, the use of solar energy technology will play a
pivotal role in meeting Libyan ׳s future energy demands.
B. Photovoltaic Energy (PV)
In recent years, there were many research works in Libya
to take advantage of the availability of solar energy to design
photovoltaic (PV) systems to meet increasing the demand for
energy and to provide energy for remote communities. [3]
investigated the application of large scale (LS-PV) A 50MW
PV-grid connected power. They carried it out by selecting a
heterojunction with intrinsic thin layer (HIT) type PV
module. A Microsoft Excel-VBA software for the modeling
and analysis parameters of this module to determine the
efficiency of this system. The results appear that the total
energy output is 128.5 GWh/year, and the average module
efficiency is 16.6%. Moreover, 85,581 tons of CO2 pollution
would reduce each year.
An evaluation of photovoltaic technology brought out
[5]. This review would be useful for people interested in this
technique. The study included the capability of power
generation, the various materials used to soak up light, its
environmental part tied with a different application. The
diverse present performance and dependability estimation
modules, sizing and control, grid connection, and distribution
have also been discussed. [6] conducted a comparative study
on grid-connected HPS lamps and a solar-powered LED
lighting system in Libya. There were illustrations and
comparisons of various aspects of capital cost, maintenance,
fuel, and CO2 production. The results have revealed that the
use of the solar-powered LED is more suitable for street
lighting due to the economic benefits and reduced loads from
the electrical grid, which has difficulty in meeting the
demand for energy, and it decreases the emission of carbon
dioxide.
C. Energy Consumption in Libya
The General Electrical Company of Libya (GECOL) in
2013 stated that an electric power grid was unable to meet
the growing consumption of energy. GECOL, in 2015,
issued a report showing that the consumption of energy is
22.035 Gigawatts (GW) in all areas. 24% of the total amount
was consumed by household loads. The problem is that
cheap energy prices due to government subsidies lead to
increased consumption of energy, which causes a shortage of
power generation[7].
The GECOL report issued in 2010 shows that the annual
demand for electricity energy increased by 9%. According to
this ratio, the energy demand will be approximately 9.5 GW
by 2020. This growth in energy demand is leading to the
depletion of conventional energy sources and resulting in
economic and environmental impacts [8].
Fig.1: Libyan load growth 2010- 2020[8]

The literature reviewed shows that the photovoltaic (PV)
systems are the most promising technologies that can be used
as an alternative energy source to traditional energy sources.
In general, the PV system is one of the most effective
alternative energy sources in Libya due to the growth in the
demand for energy and the large geographical area that
requires big investments in transmission lines to provide
remote areas. Furthermore, Libya has one of the highest daily
average direct solar radiation, which reaches 7.17
kWh/m^2/day that could be used in the production of clean
energy.
II. SIZING OF A PHOTOVOLTAIC SYSTEM BY HOMER
SOFTWARE
A. Sizing the PV system
In this study, a house in Libya has been considered for
the load profile; the total area of the house is (7.5m*20 = 150
m²). According to the study made by The Cadmus Group,
which was on three residential types in Libya: public houses,
flats, and villa, as shown in table 1. Which found that the
daily consumption (per m2) for public houses is 0.173kwh.
Then Annual average energy consumption of a house (kWh
/day), 25.95kwh/day[9].
Table 1:Residential Consumption and Demand (per m2)[9]
Upon entering data into HOMER Pro, the program will
provide an optimal electrical solution. The parameters that
we need to get results as follow:
• Determine the location of the proposed design, as shown
in figure2 below.
Fig.2: Location of proposed the PV System in HOMER PRO
• The solar resources for the location of the proposed
system, as shown in figure 3.
Fig.3: solar resource in HOMER PRO
• The house electrical load scale is 25.95kwh/day
according to the calculation, as shown in figure4.
Fig 4: Hourly load profile for a typical day
• Looking at the peak load, Schneider Conext XW+ 6848
Inverter (peak is6kW, 48V) is selected. According to [10],
the price is $3,975.
• As voltage is 48v in the bus of PV system panel is
selected 72 cell modules type (CANADIAN SOLAR
MAXPOWER2 CS6U-330P 330W POLY SOLAR
PANEL). According to[11], the price is $ 170.30.
• Trojan SSIG 12 205 battery is selected, and according to
[12], The price is $432.75.
The system design schematic with integrated subblocks
shows in figure 5 below.
Fig.5: System schematic

B. HOMER PRO optimization results
By using HOMER Pro to optimized and determine the
cost of the proposed system e findings are as shown in the
following figure.
Fig.6: HOMER sizing and optimization results.
Based on the Homer optimization result, the house needs
26 PV panels of 330 watts each, 32 batteries 12v, and
converter 5.61kw. The battery backup to feed the house at
night and the bad weather is almost two and a half days.
III. DYNAMIC MODELING AND CONTROL DESIGN OF A SOLAR
SYSTEM IN MATLAB-SIMULINK
A. The PV array Characteristics
According to the sizing of the proposed solar system, the
PV system consists of 26 CANADIAN SOLAR
MAXPOWER2 CS6U-310P 330W POLY SOLAR PANEL
photovoltaic modules. The PV curves for the PV array is
shown in Fig.7. The model is simulated for various solar
irradiations which are.
Fig.7: PV system characteristic curves in MATLAB/SIMULINK
B. Boost converter and Maximum power point tracking for
PV systems
Control the algorithm is an important stage of an MPPT,
which decides to raise or reduce the duty ratio that drives
MOSFET to find a maximum power point. MPPT controller
based on the Perturb & Observe algorithm is used in this
system.
The PV module’s output effects significantly by the
temperature and solar radiations, so a DC-DC converter is
connected between a PV module and the load in order the
PV system is continuously operating at the maximum power
point of solar radiations and temperature variations. The
perturb and observe method is used for MPPT technique in
this design by controlling the duty cycle of the boost
converter. It is one of a widely used method, while voltage
and current are applied to the function that controls the duty
cycle value according to the equation given here:
The output voltage is almost constant; the differences in
the duty cycle steadiness the variations in the input voltage.
As this maintains the current. The algorithm detects the point
at that maximum power point can be tracked, hence:
T
he idea of this method is selecting a reference voltage and
keep changing the output PV voltage to decrease the power
variation. (MPPT) Is utilizing the available maximum power
output of the PV. The algorithm is implemented according to
the flow, as shown in figure8.
Fig. 8: Perturb and observe Algorithm [14]
The main parameters in the boost converter are MPPT,
PWM, Inductor, and capacitor. The equations (3) and (4) for
the boost converter is used to determine the input and output
capacitors’ values as follows[13][14]:
Where, D max = maximum duty cycle, F sw = switching
frequency, ΔV = voltage ripple.
To increase the inductor and the current, the frequency
switch is performed in the model. The capacitor stores and
raises the DC voltage through an electric field effect. The
Pulse Width Modulation (PWM) drive is executed in the
model to stabilize the converter output voltage. A capacitor
is added to the system to store and smooth the voltage signal.

C. Inverter
This inverter contents of four IGBT’s switches (S1, S2,
S3, and S4). AC sine output voltage is generated when S1
and S4 operate under switching impulses. The transformer
connection point voltage will have a positive voltage value.
However, S2 and S4 operate at the same time at the
connection point of the transformer, and it will have a
negative polarity. The transformer is used in the model to
increase the AC voltage from 48 V to 220 V, which is the
normal voltage for the load. A diagram of the inverter is
shown below in Figure 9[13][14].
Fig.9: a diagram of the inverter in MATLAB/SIMULINK
In Figuer.10 shows the sinusoid of the voltage load.
Fig.10: simulation of the load voltage in MATLAB/SIMULINK
D. The PV system protection
One of the main elements in PV system protection is a
diode, which is used as a blocking diode to stop battery
discharge during nighttime and bypass diode to provide Path
for current when that module is shaded [15].
We also use a Fuse link in PV system protection. The
system may be contents of several PV sub-arrays (each
subarray consists of multiple strings) linked in parallel to
achieve the desired capacity of the Photovoltaic (PV) system
the fuse link is used to protect modules and conductors from
overcurrent faults and help to reduce any safety risks. Also,
ensure the continuation of the PV system to generate
electricity by isolating the faulted string. And the circuit
breaker is also used in the main panel of the load for
protection [16]. the following figure shows the proposed
protection of the system
Fig.11: Protection for PV system
IV. CONCLUSION AND DISCUSSION
The model of the PV array, residential load, Boost
Converter, MPPT controller, battery storage, and inverter is
presented in this model. The performance of the system is
assessed under various solar irradiance. The results show that
when the output power of PV array is increased
proportionally to the increase in the solar irradiance and the
output voltage of the system is almost stable even though of
the variation of the solar irradiance. The estimated cost by
using the HOMER of this system is less than or similar by
comparing it with the amount of money with the bills for 25
years. The PV system is cheaper and meets the demand of
my house consumption during the year (kWh).
Moreover, (PV) systems are the most promising
technologies that can be used as an alternative energy source
to conventional energy sources. In general, the PV system is
one of the most effective alternative energy sources in Libya
due to long hours of load shedding, especially in summer,
although Libya has one of the highest daily average direct
solar radiation. Furthermore, that could be used in the
production of clean energy and reduced the rate of carbon
dioxide emission.
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