Artículo Académico / Academic Paper
Recibido: 04-10-2022, Aprobado tras revisión: 14-06-2023
Forma sugerida de citación: Cuenca, A.; Oña, C.; Suquillo, I.; Miniguano, H. (2023). “Design Methodology of Off-Grid PV Solar
Powered Systems for Rural Areas in Ecuador”. Revista Técnica “energía”. No. 20, Issue I, Pp. 43-51
ISSN On-line: 2602-8492 - ISSN Impreso: 1390-5074
Doi: https://doi.org/10.37116/revistaenergia.v20.n1.2023.537
© 2023 Operador Nacional de Electricidad, CENACE
Design Methodology of Off-Grid PV Solar Powered Systems for Rural Areas
in Ecuador
Metodología de Diseño de Sistemas Aislados de Energía Solar Fotovoltaica
para Áreas Rurales en Ecuador
A.D. Cuenca1 C.E. Oña1 I.F. Suquillo1 H.S. Miniguano2
1Escuela de Formación de Tecnólogos, Escuela Politécnica Nacional, Quito, Ecuador
E-mail: alan.cuenca@epn.edu.ec; cristina.ona@epn.edu.ec; ismael.suquillo@epn.edu.ec
2Universidad Carlos III de Madrid, Madrid, España
E-mail: hminiguano@ing.uc3m.es
Abstract
Renewable technologies are a modern, clean form of
energy with a very low environmental impact. They
can become a viable option for energy generation,
especially in rural areas of Ecuador, where the
scarce access to electricity service limits the
development possibilities of these areas. Solar
energy is the resource used by off grid photovoltaic
generation systems, which are used exclusively in
rural areas because the installation of the electrical
grid is costly or technically complex.
Off grid photovoltaic systems have been designed in
the Matlab/Simulink environment, which are
composed of an array of photovoltaic modules,
charge controllers, storage systems and single-phase
inverters that together will allow knowing the
behavior of electric power generation through solar
photovoltaic energy. In addition, a maximum power
point tracking (MPPT) algorithm was developed to
obtain the peak power of the photovoltaic array and
a discrete integral proportional control was
incorporated for the charging and discharging of the
batteries. Finally, a sizing tool was designed and
developed through Excel Macros and Visual Basic,
which facilitated the input of different parameters
and obtaining the results for the implementation of
the photovoltaic systems.
Resumen
Las tecnologías renovables son una forma de energía
moderna, limpia y de muy bajo impacto ambiental.
Las mismas pueden convertirse en una opción viable
para la generación de energía en especial para zonas
rurales del Ecuador, en donde el escaso acceso al
servicio eléctrico limita las posibilidades de
desarrollo de estas zonas. La energía solar es el
recurso utilizado por los sistemas de generación
fotovoltaicos aislados, los mismos que son de uso
exclusivo para zonas rurales debido a que la
instalación de la red eléctrica es costosa o
técnicamente compleja.
En el entorno de Matlab/Simulink se han diseñado
sistemas fotovoltaicos aislados que están compuestos
por un arreglo de módulos fotovoltaicos, reguladores
de carga, sistemas de almacenamiento e inversores
monofásicos que en conjunto permitirán conocer el
comportamiento de la generación de energía
eléctrica a través de energía solar fotovoltaica.
Además, se desarrolló un algoritmo de seguimiento
del punto de máxima potencia (MPPT) para obtener
el pico de potencia del arreglo fotovoltaico y se
incorporó un control proporcional integral discreto
para la carga y descarga de las baterías. Por
consiguiente, se diseñó y desarrollo una herramienta
de dimensionamiento a través de Macros y Visual
Basic de Excel, la cual facilitó el ingreso de los
diferentes parámetros y la obtención de los
resultados para la implementación de los sistemas
fotovoltaicos
Index terms−− Energy generation, Solar energy,
dimensioning, Simulink, Visual Basic.
Palabras clave−− Generación de energía, energía
solar, dimensionamiento, Simulink, Visual Basic.
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Edición No. 20, Issue I, Julio 2023
1. INTRODUCTION
Renewable energies are all types of energy that can
be produced continuously and are inexhaustible on a
human scale, i.e., they are replenished at a higher rate
than they are consumed, unlike fossil fuels that exist in a
limited quantity and are exhaustible in a determined
period [1]. The main forms of renewable energies that
exist are biomass, wind, hydro, solar, geothermal, and
marine energies, which come directly or indirectly from
the sun's energy, except for marine and geothermal
energies [2]. Nowadays, the use of renewable energies
haves been boosted to contribute to the care and
preservation of the environment. The climate change
caused by the expulsion of CO2 into the atmosphere by
industries, vehicles, burning of fossil fuels, etc., has led
to the development of technology in different regions of
the world to obtain energy (electric or thermal). This has
led to the development of technology in different regions
of the world to obtain energy (electrical or thermal) from
renewable sources such as the sun.
The use of photovoltaic energy has spread in recent
years to different regions of the planet and Ecuador is no
exception, since it is a country with very varied
topographic features, great climatic diversity and unique
conditions that give it a high potential for the use of
renewable and clean energy. Off-grid power systems are
supplied by different renewable energy sources, although
these sources are often intermittent, their use is taking
place in both developed and process developing such as
Ecuador. This is due to several factors, such as the
downward trend in the cost of photovoltaic systems, as
well as improved technology and falling prices of
electrical storage systems [3].
In this paper, to compensate for the previous
drawbacks explained while maintaining a degree of
generality is the development of a simulation case study
for a photovoltaic generation using the Simulink software
of Matlab to know the behavior of electric power
generation through photovoltaic energy.
The scheme of the off grid photovoltaic systems
developed in the Simulink environment is composed of
an array of photovoltaic modules, a charge controller, a
storage system, and a single-phase inverter. In addition,
a maximum power point tracking (MPPT) algorithm was
developed to obtain the maximum power of the array and
a discrete proportional control for battery charging and
discharging was incorporated.
In addition, for the dimensioning of an off grid
photovoltaic system, a tool was designed and developed
using Excel Macros and Visual Basic, to facilitate the
input of parameters and obtain the results simply and
efficiently.
2. METHODOLOGY
For the development of the project, electricity
demand data from three rural areas on the coast,
highlands and Amazon regions of Ecuador were used.
Based on this data [4], each of the components of the off
grid photovoltaic systems was dimensioned. The
simulation was carried out based on the electrical power
demand and the solar resource obtained from the
software of the European Commission Joint Research
Center called Photovoltaic Geographical Information
System (PVGIS), which allows for obtaining global
radiation data. In addition, the dimensioning of the off
grid photovoltaic system considered technical reports
such as: “Balance Energético Nacional 2020” prepared
by the Instituto de Investigación Geológico y Energético
(IIGE) trought which it was possible to know how the
people of Ecuador have increased the use of electric
energy for different household, commercial and industry
activities [5], “Microgeneración” of the Agencia de
Regulación y Control de Energía y Recursos Naturales
no Renovables (ARC) to know the regulation for off grid
electrical systems [6] and “Atlas solar del Ecuador” of
the Corporación para la Investigación Energética (CIE)
to study the behavior of solar radiation in different
regions of the country [7]. Consequently, a sizing tool
based on Macros and Visual Basic was developed
through Excel, which facilitated the input of different
parameters.
Once the results were obtained through the sizing
tool, an algorithm called maximum power point tracking
(MPPT) was developed to obtain the maximum power of
the PV array. In addition, a discrete integral proportional
control was incorporated for the control of the batteries.
The parameters and algorithms were used to perform
the simulation and performance tests in the Simulink
environment of Matlab to obtain the curves of voltage,
current and power generated by the photovoltaic systems,
in addition, it was verified that the generation is capable
of meet the demand.
2.1. System Requirements
Ecuador is a country that has very varied topographic
characteristics, so it has a high potential for the use of
photovoltaic solar energy. According to [8], the average
global radiation values in Ecuador are homogeneous,
which translates into a significant reduction in the
problem of random variations of this resource. In
addition, it provides confidence and profitability for the
use of photovoltaic technology in the country [9-13].
The increase in population and the growing demand
for electrical energy per inhabitant [14], makes it
necessary to carry out studies that allow us to know how
photovoltaic energy can be used to electrify different
areas of Ecuador, especially those in which the
conventional grid is limited by the difficulties of access
inherent to nature. For this reason, three rural areas from
different regions of Ecuador have been chosen for the
study of the solar resource: coast region (Pedernales),
highlands region (Ambuquí) and amazon region
(Cuyabeno).
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Cuenca et al. / Design Methodology of Off-Grid PV Solar Powered Systems for Rural Areas in Ecuador
The PVGIS software was used to study solar
resources, from which global radiation data were
obtained for each of the selected areas. Table 1, Table 2,
and Table 3 show the global radiation data for different
regions and the peak sun hours (PSH) corresponding to
2015. The data obtained from the three places mentioned
are provided by PGVIS because this online tool provides
information on solar radiation and the performance of the
photovoltaic (PV) system for any location in the world.
Table 1: Global radiation data (Pedernales)
Year
Month
kWh/m²
PSH
2015
January
131,52
4,38
2015
February
127,01
4,23
2015
March
153,92
5,13
2015
April
167,89
5,60
2015
May
152,6
5,09
2015
June
143,8
4,79
2015
July
129,78
4,33
2015
August
135,15
4,51
2015
September
138,96
4,63
2015
October
141,96
4,73
2015
November
135,46
4,52
2015
December
152,46
5,08
Table 2: Global radiation data (Ambuquí)
Year
Month
kWh/m²
PSH
2015
January
165,39
5,51
2015
February
162,6
5,42
2015
March
152,76
5,09
2015
April
149,13
4,97
2015
May
159,09
5,30
2015
June
146,79
4,89
Year
Month
kWh/m²
PSH
2015
July
161,47
5,38
2015
August
169,94
5,66
2015
September
190,47
6,35
2015
October
5,61
2015
November
5,54
2015
December
6,29
Table 3: Global radiation data (Cuyabeno)
Year
Month
PSH
2015
January
4,01
2015
February
4,19
2015
March
3,79
2015
April
4,09
2015
May
4,01
2015
June
3,78
2015
July
3,99
2015
August
4,79
2015
September
5,59
2015
October
5,25
2015
November
4,72
2015
December
4,39
With the solar resource data of each one of the
selected areas, and through an analysis of the electrical
demand data presented in [4] and [5], the dimensioning
of the off grid photovoltaic systems begins.
2.2. Component Modeling
The off grid photovoltaic system developed in the
Simulink environment consists of the following
elements:
2.2.1 Photovoltaic Module Array
The photovoltaic module harnesses the solar energy
incident on its surface to convert it into electrical energy
in the form of direct current.
Off grid photovoltaic systems use a certain number of
modules according to the electrical demand to be
satisfied [15]. In the Simulink environment, it is
necessary to place a capacitor and resistor in parallel to
stabilize the voltage and current at the output of the array
of panels (Fig. 1), which will allow coupling of the
charge regulator (Fig. 2).
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Edición No. 20, Issue I, Julio 2023
Figure 1: Photovoltaic array resistor and capacitor
2.2.2 Charge Regulator
It is one of the most important elements within an off
grid photovoltaic system since its main function is to
avoid situations of overcharge and over-discharge of the
battery, with the sole purpose of increasing its useful
lifetime [16].
The load controller developed in the Simulink
environment is shown in Fig. 2 and is composed of a step-
down converter and a bidirectional converter.
Figure 2: Load controller model in Simulink
In addition, the charge controller is complemented by
the following algorithms:
• MPPT: the maximum power point tracker will
allow obtaining the peak power of the PV array
[17]. The algorithm used for this control technique
is the Perturb and Observe (P&O) algorithm (Fig.
3) which is responsible for perturbing the
operating voltage to ensure the photovoltaic
modules deliver their maximum power.
Figure 3: Perturb and observe algorithm
• Discrete integral proportional control: this type of
control allows for the correction and
compensation of disturbances to maintain the
voltage and current variable within the parameters
already established for the charging and
discharging of the battery.
Three integral type proportional controls were
developed in the Simulink environment.
Fig. 4 shows the current control that will govern the
action of the bidirectional converter IGBTs for charging
and discharging the batteries.
Figure 4: Discrete PI control for control of IGBTs
Fig. 5 shows the charge voltage control that allows
obtaining a reference co-current for battery charging.
Figure 5: Discrete PI control for charge voltage control
Fig. 6 shows the discharge voltage control to obtain a
reference current for discharging the batteries, in such a
way that it can allow the inverter to operate.
Figure 6: Discrete PI control for discharge voltage control
2.2.3 Storage System
This system (Fig. 7) makes it possible to store the
electrical energy produced by the photovoltaic array and
use this energy at times when the radiation received by
the modules is not capable to achieve the photovoltaic
power required to meet the demand.
Figure 7: Battery model in Simulink
2.2.4 Inverter
This element allows converting the direct current of
the storage system into alternating current, same as the
provided by the power grid for the residential sector: 110
or 120 (VAC) and a frequency of 60 (Hz). The single-
phase inverter developed in the Simulink environment is
shown in Fig. 8, which is composed of a step-up
converter, IGBT bridge and LC filter [18].
Figure 8: Single-phase inverter model developed in Simulink
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Cuenca et al. / Design Methodology of Off-Grid PV Solar Powered Systems for Rural Areas in Ecuador
2.3. Sizing Tool
To carry out the load study and determine each of the
parameters that make up the photovoltaic system, a
dimensioning environment was developed using Macros
and Visual Basic in Excel. In addition, there is a database
with the datasheets of the components of the off grid
photovoltaic system based on the local market offer.
Fig. 9 shows the window to perform the load study,
in which it is possible to Add, Edit, or Delete electrical
loads. In addition, the daily consumption and total
maximum demand of all aggregated loads will be
obtained.
Figure 9: Power of specific loads
Fig. 10 shows the interface for PV module sizing,
where the following data will be obtained: oversized
daily consumption (Wh), system voltage (V), PV power
(W) and several PV modules. With the oversizing of the
daily consumption with factors of 20, 25 or 30%, it is
assured that the photovoltaic system is capable of
satisfying the electrical demand in the event that all
electrical loads work simultaneously. In addition, system
losses due to temperature coefficients, cloudiness and
atmospheric conditions are compensated.
Figure 10: Photovoltaic module sizing
Fig. 11 shows the window for sizing the charge
controller, open-circuit voltage Voc (V), short-circuit
current Isc (A) and total power (W) will be obtained in
this interface. With the previous data, the most suitable
charge regulator can be selected.
Figure 11: Sizing of the charge controller
For the sizing of the single-phase inverter, the
window shown in Fig. 12 is used and with the oversized
peak demand data, the inverter with the most suitable
electrical power is selected.
Figure 12: Sizing of the single-phase inverter
Fig. 13 shows the interface for sizing the DC electric
energy storage system where the following data must be
entered: days of autonomy, discharge depth (%), battery
capacity (Ah), and battery voltage (Vdc). With the data
entered above, the number of batteries in series and
parallel is obtained.
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Edición No. 20, Issue I, Julio 2023
Figure 13: Sizing of the storage system
In each of the windows developed for the
dimensioning of the components of the off grid
photovoltaic system, there is a button with the Simulink
symbol that allows you to enter another macro interface,
where the values of the components are obtained for the
respective simulation of the system.
3. RESULTS AND DISCUSSION
The schematic of the off grid photovoltaic system
developed in the Simulink environment is presented in
Fig. 14.
Figure 14: Off grid photovoltaic system in Simulink
According to [19], the average radiation that reaches
the earth's surface is 1000 (W/m²). This value is used
together with the irradiation data in Table 1, Table 2, and
Table 3 to calculate the PSH. Important data to determine
the necessary photovoltaic power to cover the demand in
the chosen areas.
Case study 1: Pedernales site. Fig. 15 shows the
curves obtained by the photovoltaic array. The voltage
has a maximum value of 18.49 (Vdc), the maximum
current value is 17 (Adc) and the power obtained is 299.6
(W).
Figure 15: Pedernales PV array curves
The curves of the single-phase inverter are shown in
Fig. 16. The current has a peak value of 3.01 (Aac), the
voltage has a peak value of 174 (Vac) and the power is
497.70 (W).
Figure 16: Curves of the single-phase inverter at Pedernales
Case study 2: Ambuquí site. In Fig. 17, the curves of
the Ambuquí photovoltaic array are presented. The value
obtained in the voltage curve is 36.01 (Vdc) and the
maximum output current has a value of 19.17 (Adc). The
power for this area is 690.20 (W).
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Cuenca et al. / Design Methodology of Off-Grid PV Solar Powered Systems for Rural Areas in Ecuador
Figure 17: Ambuquí PV array curves
In Fig. 18, the curves of the single-phase inverter in
the Ambuquí area are presented. The current reaches a
peak value of 27.57 (Aac) and the voltage reaches a peak
value of 159.3 (Vac). The output power of the inverter is
4359 (W).
Figure 18: Ambuquí single-phase inverter curves
Case study 3: Cuyabeno site. In Fig. 19, the curves
of the photovoltaic array of the Cuyabeno are shown. The
voltage reaches a value of 31.29 (Vdc) and the current
has a value of 8.62 (Adc). The power reaches a value of
269.9 (W).
Figure 19: Cuyabeno photovoltaic array curves
In Fig. 20, the curves of the single-phase inverter in
the Cuyabeno area are shown. The current has a value of
2.53 (Aac) and the voltage has a peak value of 182.9
(Vac). The peak power reached is 401.9 (W).
Figure 20: Cuyabeno single-phase inverter curves
The Maximum Power Point Tracking (MPPT)
algorithm will always obtain the peak power of the PV
array, which will avoid power fluctuations due to
changes in parameters such as irradiation since the solar
resource is variable during the day.
The simulated MPPT charge controller allowed
obtaining optimal voltages and currents for the storage
system, thus avoiding overvoltage or overcurrent, and
guaranteeing the stability of the battery parameters.
The discrete PI control developed allows controlling
only the charge and discharge of the batteries. The
electronic protections that the regulator has for
overcharge and over-discharge conditions are not
considered for the simulation.
4. CONCLUSIONS AND RECOMMENDATIONS
The possibilities and benefits that offer photovoltaic
solar energy in rural areas of Ecuador were known after
the analysis in the present paper. This simulation
corresponds to a suitable tool for a study before the
implementation of this type of renewable generation
system.
The number of photovoltaic modules varies
according to the peak power of the chosen module, so the
selection of a small power panel will imply an increase
in the number of solar panels to obtain the required
photovoltaic power.
The results obtained in each of the simulations
performed in the Simulink software are considered ideal
values because the losses are due to the self-consumption
of power of the elements of the off grid photovoltaic
system and energy transport through electrical
conductors is not modeled by the environment.
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Edición No. 20, Issue I, Julio 2023
The dynamics tool developed in Excel Macros and
Visual Basic will facilitate the study, dimensioning and
implementation of the off grid photovoltaic systems due
to its simple and efficient interface.
With the values obtained in the different case studies
of this work, it is shown that it is possible to size and
simulate off grid photovoltaic systems in a simple and
dynamic way, which allows supplying various values of
energy demand, considering that the energy supply has
become a necessity for the development and good quality
of life of people.
The work done can be considered for the
development of future simulation studies and later
implementation of the off grid photovoltaic systems,
especially in rural areas of Ecuador where the lack of
access to electricity limits the development of other
technologies such as information and communication.
Based on the demands of the current panorama, rural
locations must work to achieve a reliable, effective,
efficient, sustainable and economic energy supply to
guarantee progress and rural development. It is in this
context, where the option of the off grid photovoltaic
systems is used as an alternative to access electricity.
The developed tool proposes to the off grid
photovoltaic systems as an energy solution that must be
implemented more frequently on a small, medium and
large scale; either due to being in isolated areas that are
difficult to access or simply due to lack of coverage of
the national interconnected system.
SINCERE APPRECIATION
A very special thanks to the Escuela Politécnica
Nacional and the Escuela de Formación de Tecnólogos
for their unconditional support during the completion of
this research work.
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[9] R. Buitrón y G. Burbano, «Elaboración de una
normativa para el diseño y diagnóstico de sistemas
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[10] 10. L. G. Macancela Zhumi, «Diagnóstico de la
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Yantsa ii Etsari,» Universidad de Cuenca, Cuenca,
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[11] Corporación para la Investigación Energética,
«Atlas Solar del Ecuador con Fines de Generación
Eléctrica,» Quito, 2008.
[12] Departamento de Infraestructura y Energía del BID,
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[15] B. Guirau, F. Marcato y W. Pereira, «Circuito
microinversor aplicado a sistemas fotovoltaicos
autónomos,» Universidad de São Francisco,
Campinas(SP), 2015..
[16] Barrenetxea , «Sistema fotovoltaico aislado:
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[20] Cuenca Sánchez, A. D. (2015). Fiabilidad de la
generación eléctrica con energías renovables en la
provincia de Loja-Ecuador (Master's thesis,
Madrid/Universidad Carlos III de Madrid/2015).
Alan Cuenca Sánchez. - He was
born in Celica in the province of
Loja in 1989. He received his
degree in Electronics, Automation
and Control Engineering from the
Universidad de las Fuerzas
Armadas ESPE in 2012; and the
Master in Renewable Energies in
Electrical Systems from the Carlos III de Madrid
University, in Spain in 2015. His research fields are
related to Energy Efficiency, Renewable Energies,
System Automation, and Industrial Instrumentation.
Cristina Oña Pilliza. - She was
born in Quito in 1997. She received
her Electromechanical
Technologist degree from the
Escuela Politécnica Nacional in
2021. Her field of research is
related to Renewable Energies.
Ismael Suquillo Lugmaña. -He
was born in Sangolquí in 1998. He
received his Electromechanical
Technologist degree from the
Escuela Politécnica Nacional in
2021. His field of research is
related to Renewable Energies.
Henry Santiago Miniguano.- He
was born in Ambato in 1984. He
received his degree in Electronics,
Automation and Control
Engineering from the Universidad
de las Fuerzas Armadas ESPE in
2008; and that of Doctor in
Electrical and Electronic
Engineering from the Carlos III de Madrid University, in
Spain in 2019. Currently, he is teaching at the Carlos III
de Madrid University, and his field of research is related
to Power Systems and the Electric Vehicle.
51