2018 5th International Conference on Electrical and Electronics Engineering

Photovoltaic Systems with Rotational Panels to Harvest Natural and Artificial Light
for Electrical Production

Mahmoud Bagheritabar Hamed Bagheitabar

Electrical and Computer Engineering Department Department of Electrical and Energy Engineering
Islamic Azad University, North Tehran Branch Islamic Azad University, Damavand Branch
Tehran, Iran Tehran, Iran
e-mail: mahmoud.bagheritabar@gmail.com e-mail: ham_bagheri@yahoo.com

Mohammad Mansour Riahi Kashani Niloofar Sayyad Khodashenas

Electrical and Computer Engineering Department Department of Aeronautical and Vehicle Engineering
Islamic Azad University, North Tehran Branch MWL
Tehran, Iran KTH Royal Institute of Technology
e-mail: m_riahi_kashani@iau-tnb.ac.ir Stockholm, Sweden
e-mail: nisk@kth.se

Abstract—Regarding the fact that huge amount of non- power. Long hours at night has an important impact on the
renewable energy is extracted, distributed, converted and solar energy received by a photovoltaic cell moreover most
consumed for electrical demands in the Building-Integrated photovoltaic modules have low efficiency hence, one of the
Photovoltaic systems, using the rotational photovoltaic panels concerns about the use of low-voltage photovoltaic power
as a source of energy would be more convenient. Optimization plants, usually connected to domestic, industrial, or industrial
of this system which harvests outdoor natural light and indoor consumers, is the lack of power output for photovoltaic
artificial light is an enormous need to maximize the solar panel arrays. Solar energy, in addition to its inexhaustible nature, is
efficiency. In this paper to achieve the main purpose, an the source of human enormous energy and is also available
experimental attempt has been made to model the wall and
in many parts of the world, and it is clean energy. Nowadays
window built PV system as economical as possible. The
performance of this model is carried out on the facade of
BIPV 1 methods is a good way for harvesting sunlight for
buildings with a Manual switch for rotation. The result of this electricity production since they are increasingly being
experiment has shown that the system is more efficient. incorporated into the construction of new buildings as a
principal or ancillary source of electrical power, although
Keywords-renewable energy; solar cells; building-integrated existing buildings may be retrofitted with similar technology.
photovoltaic system; rotational panel; artificial light; efficiency

I. INTRODUCTION
Today, the need to use clean and renewable energy
sources has become extremely important, given the growing
demand for energy from the world as well as the limited
availability of fossil fuels and pollution by these resources.
One of the most important sources of renewable energy is
solar energy. In general, this technology is divided into two
categories of solar thermal systems and photovoltaic
systems, in which photovoltaics are used here due to their
electric production. The photovoltaic panels are made of
semiconductors and are formed by bonding n and p-type
silicon furthermore when the sun shines to a photovoltaic
cell, it gives the electrons more energy thus the light of the
sun polarizes the electrons in the semiconductor, forming
negative electrons in the n-type silicon and positive ions in p- Figure 1. The process of electricity generation by a photovoltaic cell.
type silicon. In this way, a potential difference is created
between the two electrodes, which cause the current to flow The advantage of integrated photovoltaics over more
between them. Fig. 1 shows how electricity is generated in a common non-integrated systems is that the initial cost can be
photovoltaic cell. However artificial lights are also able to do
the exact same phenomenon to the cells only with less 1
Building-Integrated Photovoltaic

978-1-5386-6392-9/18/$31.00 ©2018 IEEE 211

offset by reducing the amount spent on building materials 1000 W/m2 moreover the output power (Po) was calculated
and labor that would normally be used to construct the part 7.38 Watts consequently it has an ideal efficiency of 16.4%.
of the building that the BIPV modules replace. These Po
K (2)
advantages alongside installation on the façade of buildings E * AC
without occupying the area of the ground make BIPV one of
the fastest growing segments of the photovoltaic industry. A. Calculating the Output Power of the System
Most buildings are lightened until night or even at midnight,
According to the specification of the tested panel, the
therefore, mixing natural and artificial light can gather more
output power is at a maximum of 5 watts. With the average
amount of electricity production rather than a single type of
amount of solar power produced as Fig. 3, which is 678.72
light.
w/m2 for a period of 5.5 hours per day, the maximum output
II. COMPONENTS SELECTION AND DESIGN power is equal to 3.3935 watts, according to (3) it equals
18.6648 watt-hours per a day.
Many factors, such as sunlight, weather conditions, Electrical Energy= Po* Average Irradiation Duration (3)
shadow, temperature, dust, wind, and snow, have a
significant effect on the solar energy received by a
photovoltaic cell [1-5]. The maximum output power is
obtained by (1), which is calculated from the maximum
output voltage and current that is available in the
specifications of each panel [6].
Pmp= Vmp * Imp (1)
According to the characteristics in [7], the efficiency of
single-junction monocrystalline silicon cell is 26.7%, also it
has the highest confirmed conversion efficiency out of all
commercial PV technologies, ahead of Poly-Si (22.3%) and
established thin-film technologies such as CIGS cells Figure 3. Power of the sunlight on the panel.
(21.7%), CdTe cells (21.0%), and a-Si cells (10.2%). The
high efficiency is largely attributable to the lack of B. Outputs of the Experiment
recombination sites in the single crystal, and better
absorption of photons due to its black color as compared to Providing Air Mass (AM) = 1.5, and with the
the characteristic blue hue of poly-silicon. With this in mind, temperature and power of the sun, the condition of the cells
the best option is a Mono-crystalline silicon photovoltaic in BIPV mode is compared to the IEC 60904 standard. Since
system although Organic cells are good with artificial light the main objective of the experiment is to improve the
but not with natural light [6]. function of the photovoltaic system, it is necessary to
Panels will use sunlight after the sunrise and after measure the voltage and current of the system. For this
completion of the hours of exposure to the sun, the cell is purpose, a circuit is designed in Fig. 4. For ease of
rotated 180 degrees, in accordance with Fig. 2, in order to understanding of the operation of the circuit, it should be
place in front of the artificial light at a 90-degree angle and noted that the photovoltaic cell is considered as a voltage
panels will rotate one more time at midnight for tomorrow. source, and in the output direction, a load of 1 kΩ is placed
Therefore, a shaft is required for the spinning of each row in series. Finally, the output power will be calculated by (1).
and one electromotor or even a simple handle with gears for In the first step, the power of sunlight was measured by
all of the rows to return. the solar power meter (pyrometer) in the vertical mode. The
average value for Tehran peak sun-hours is 5 hours and 30
minutes with an irradiance of 1,000 watts per square meter
since sun-hours increases during the summer due to the sun’s
higher position in the sky moreover solar energy increases
near the equator, as it is closer to the sun. Another variable is
the temperature which is measured by a thermometer and the
deviation from 25° Celsius is calculated.

Figure 2. The method used to rotate the panels.

III. THE CALCULATION METHOD

The efficiency (η) of the panel in maximum standard
conditions is determined in accordance with (2), which area
of collectors (Ac) is 0.045 m2 in this panel furthermore
according to IEC 60904 [8] incident radiation flux (E) is 
Figure 4. The equivalent circuit for testing panel output.

212
 IV. RESULTS
The average value for a day and night is 155.54 w/m2
and for a standard rate of 5 hours and 30 minutes is 678.72
w/m2, which is lower than the standard, due to the
perpendicularity of sunlight on the panel. The ambient
temperature is compared to the standard, is shown in Fig. 5
which deviates about ±5 degrees from 25 Celsius and it is
very close to the standard which is considered 25° Celsius.

Figure 7. The current of the solar panel by time.

Therefore, in order to obtain the power of natural light,

the voltage and current of the experiment shall be used in (1).
With averaging and calculating the surface below Fig 8, the
output from the natural light is 308.5 watts per hour over a
day.

Figure 5. The temperature of the panel’s surface.

Since there is no standard for artificial light power, this

value can be compared with previous experiments [6] where
the light is set as a fixed standard and is 500 Lux, according
to the standard. The amount of artificial light power is up to
5 watts per square meter, which is much less than the natural
light that varies from 100 to 1000. Seven types of artificial
light used in this experiment are specified Table I.

TABLE I. ARTIFICIAL LIGHTS USED Figure 8. The power of the solar panel by time.

Abbreviation Light type description The power of each type of light is calculated by an
F2 Fluorescent Lamp artificial light test device that has the power to control the
F11 Low consumption Fluorescent Lamp Lux of the light from 0 to 1500 watts per square meter. By
Warm LED Yellow LED lamp using Table I light types and a lux meter the Fig. 9 results are
HP5 Metal Halide Lamp (Metal Halogen) achieved.
F7 Sunshine Fluorescent Lamp
Cool LED Yellow LED lamp
HP1 High-pressure sodium lamp

According to the experiment, the solar panel voltage by

time is shown in Fig. 6. Further, the diagram of the current
by seconds, with a resistance of 1 kΩ as the load is shown in
Fig. 7.

Figure 9. Output power of different artificial lights.

The sunset on August is about 20:00 thus panels rotation

shall be done on that time and four hours of artificial light is
considered for most buildings since the average light usage
at nights in summers are until on midnight. In Fig. 10, the
rotation time of the panels is set at sunset, and after the
Figure 6. The voltage of the solar panel by time.
panels are rotated, the output power is calculated.

213
 artificial light is Metal Halide Lamp and High-pressure
sodium lamp respectively but a mixture of warm and cool
LED would be a good choice for lighten up the place and
recycle some electricity back to the grid.

VI. FUTURE WORKS

In summer, due to longer days, the lowest increase will
be achieved and in winter the highest return is obtained. This
experiment was carried out on August 26, 2016, when the
values obtained from the natural light are quite bigger than
the artificial light for the difference between the sunlight
Figure 10. Rotation time of the panels in each month.
power in those seasons. Another reason is the duration of the
In the end, the natural light power effect along with day since it is longer in the summer and the average power
artificial light is calculated and the increase of using the obtained until the sunset is more than winter furthermore
indoor lights only for 4 hours can be seen in Table II. different types of photovoltaic cells act differently by
exposing to different natural and artificial lights,
TABLE II. THE INCREASE OF EFFICIENCY ON THE EXPERIMENT DAY consequently using different type of panels or seasons may
cause enormous change in the results.
Artificial light type Increased efficiency
F2 3.54 % REFERENCES
F7 4.366 % [1] A. Zulu and G. Kashweka, "The Influence of Artificial Light and
F11 3.565 % Shading on Photovoltaic Solar Panels." International Journal of
Cool LED 3.577 % Energy Engineering, pp: 15-20, 2013.
Warm LED 3.768 % [2] N. Mutoh, M. Ohno and T. Inoue. "A method for MPPT control while
searching for parameters corresponding to weather conditions for PV
HP1 3.409 % generation systems. "IEEE Transactions on Industrial Electronics,
HP5 4.785 % pp: 1055-1065, 2006.
[3] T. R. Wheeler, P. Q. Craufurd, R. H. Ellis, J. R. Porter and P. V.
Prasad, “Temperature variability and the yield of annual crops”.
V. CONCLUSION Agriculture, Ecosystems & Environment, pp: 159-167, 2000.
[4] C. H. Bock, P. E. Parker, and T. R. Gottwald, "Effect of simulated
Since the experiment was conducted in Tehran with wind-driven rain on duration and distance of dispersal of
latitude and longitude of 35.415903 and 51.201698 Xanthomonas axonopodis PV. Citri from canker-infected citrus
respectively in summer with a given period, the results of the trees." Plant Disease, pp: 71-80, 2005.
experiment will vary for each city and season and the [5] L. Powers, J. Newmiller and T. Townsend, "Measuring and modeling
duration of the other radiation. In general, there is no the effect of snow on photovoltaic system performance." In
standard for BIPV and all values are compared to IEC Photovoltaic Specialists Conference (PVSC), 2010 35th IEEE, 2010,
pp. 000973-000978.
60904, which is less than the standard in this experiment.
[6] B. Minnaert and P. Veelaert, “A proposal for typical artificial light
Comparing the power values obtained in the theoretical sources for the characterization of indoor photovoltaic applications.”
model, which is 18.66 Wh and is equivalent to 5.83 Wh, in Energies, pp. 1500-1516, 2014.
the experiment, 31% of the maximum power of the panel has [7] F. Brivio, “Atomistic modeling of perovskite solar cells.” Ph.D.
been utilized, which indicates the high return of the dissertation, Dept. Chem. Eng., Bath Univ. Som., UK, 2016.
photovoltaic system of the BIPV. The reason for this [8] J. H. Wohlgemuth, "Standards for PV Modules and Components-
phenomenon is the reflection of sunlight from the surface of Recent Developments and Challenges: Preprint.", In 27th European
the panel due to its transparency, the fluctuation of the Photovoltaic Solar Energy Conference, Frankfurt, Germany. 2012.
current due to the presence of a cloud shadow and changes in [9] J. Zhao, A.Wang, M. A.Green and F. Ferrazza, "19.8% efficient
the temperature, and in reality, the maximum power is never “honeycomb” textured multicrystalline and 24.4% monocrystalline
silicon solar cells." Applied Physics Letters, pp: 1991-1993, 1998.
obtained as a constant value [9]. The best and the worst

214