`Optimum tilt and orientation angles for photovoltaic panels
in the Vaal Triangle
Osamede Asowata, James Swart, Christo Pienaar and Ruaan Schoeman
Department of Electronic Engineering
Vaal University of Technology, Private Bag X021, Vanderbijlpark, 1900
Corresponding author email: asowatao@vut.ac.za
Abstract – Optimising the output power of a
photovoltaic panel improves the efficiency of a solar
driven energy system. The maximum output power of a
PV panel depends on atmospheric conditions, load
profile and the tilt and orientation angles. In this study,
an experimental analysis of maximizing output power of
a PV panel is carried out, based on the use of existing
equations of tilt and orientation angles derived from
mathematical models and simulation packages. A data
logger, DC-DC converter/maximum power point tracker,
fixed load resistance and single PV panel is used. The PV
panel is set to an orientation angle of 0o with tilt angles of
16o, 26o and 36o.
I. INTRODUCTION
The release of energy has not created a new problem,
but has made more urgent the necessity of solving an
existing one [1]. In the quest to harness clean cheap energy
from the sun, a phenomenon was discovered in the early
19th century, where electrical energy is generated using the
photovoltaic (PV) effect [2]. The sun is approximately 1.4
million km in diameter and 150 million km from the earth. It
has a surface temperature close to 5500 oC and it emits
radiation at a rate of 3.8x1023 kW per second on an average
daily basis [3]. Solar energy is supplied by nuclear fusion
reactions near its core which are estimated to continue for
several billion years.
Solar energy can be converted directly into electricity with
modules consisting of PV cells. Electricity is usually
manufactured from fine film semiconductor devices capable
of converting incident solar energy into DC current. Its
efficiency varies from 3 to 31%, depending on the
technology, the light spectrum, atmospheric condition,
temperature, design and the material used [4]. A PV panel
can be employed in small and large scale applications such
as auxiliary electric generators and stand alone power plants.
This depends on the available surface area exposed to the
sun [5].
The purpose of this study is to optimize the available output
power from a PV panel. Mathematical models and
simulation packages in combination with experimental data
will be used to determine the optimum tilt and orientation
angles. This will enable a higher yield of solar energy,
thereby reducing dependence on traditional energy sources
such as fossil fuels. This study will assist in identifying ways
to improve the installation of PV panels for optimum output.
Figure 1 shows a diagram of the tilt (yp) and orientation
angles (αp) of the PV panel. This research involves a
designed experimental approach involving quantitative data
where descriptive statistics will be used.
Figure 1. Tilt and orientation angles of a PV panel.
II. PROPOSED SYSTEM
Figure 2 shows a block diagram of the system. The system
comprises a PV panel connected to a DC-DC convertor or a
maximum power point tracker (MPPT) and a constant load
resistance.
Temperature
measurements
PV Panel
Different tilt
and
orientation
angles
P (source) =
(Vi x Ii)
DC-DC
converter
OR
MPPT.
P (load) =
(Vo x Io)
Constant
load
resistor
Power regulation
Figure 2. The practical set-up.
The PV panel is placed at different orientation and tilt
angles, while a pyrometer is used to measure the temperature
of the PV panel. Determining the optimum tilt angle
involves placing the PV panel at an orientation angle of 0o
and changing the angle of tilt to 16o, 26o and 36o
respectively. These angles are derived from the Heywood
and Chinnery equations of latitude for calculating tilt angles
of PV panels in South Africa, shown in Table 1.
Vanderbijlpark lies on latitude of 26o south, giving the
mathematical results for tilt angles.
Table 1. Calculation of tilt angles.
Latitude
26o
26o
26o
Equation
Ф-10
ф
Ф+10
Calculation
26o-10
26o
26o+10
Tilt angle
16o
26o
36o
A DC-DC converter is connected to the PV panel to regulate
the output power from the PV panel. A data logger is used to
collect measurements (input voltage, output voltage, input
current and output current). The experiment is repeated
taking two samples each using the 16o, 26o and 36o. The two
samples ensure test-retest reliability of the measuring
instrument which must be administered on at least two
occasions [6]. The orientation angle is changed to –αo and
+αo respectively (α being the orientation angle). Lastly, the
entire process is repeated using a MPPT to determine which
power regulation process is more efficient.
In total, a minimum of 18 samples are to be collected over
an 18 week period with regression analysis being used to
determine the best tilt and orientation angle for optimal
power from a PV panel. Atmospheric conditions in terms of
industrial pollution and cloud movement will have a bearing
on the total number of samples. It is difficult to account
accurately for these factors and may require additional
research.
III. INITIAL RESULTS
Table 2. Sun module SW220 poly-crystalline PV panel
Abbreviation
PMAX
VOC
VMPP
ISC
IMPP
IV. CONCLUSION
In review, the purpose of this study is to optimize the
available output power from a PV panel. This will enable a
higher yield of solar energy, thereby reducing dependence
on traditional energy sources such as fossil fuels. Figure 3
showed a plot of voltage to time for different elevation
angles, verifying the open circuit voltage of 36 V. The day
temperature is also shown in Figure 3, which exerts a
negative influence on the open circuit voltage. This research
will involve many more experiments using different load
resistances, with various tilt angles of 16o, 26o and 36 o. A
number of different DC-DC converters and MPPT will also
be used to determine the most efficient power regulator.
Finally, the comparison of the experimental data to the
results obtained from the simulation packages, mathematical
models and equations of latitude will provide an optimum
installation guide.
V. REFERENCES
True north is determined using a GARMIN Etrex GPS
handheld device. The solar panel is orientated parallel to this
direction resulting in an orientation angle of 0°. Exact
longitude and latitude angles for the installation of the single
solar panel on the roof of the S-Block at VUT are obtained
with this device (Latitude: 26°42, 649’ S and Longitude:
27°51, 809’ E). A PV panel from solar world [7] is used in
this study, with the following specifications as shown in
Table 2. Preliminary results for open circuit voltages are
presented in Figure 3.
Specification
Maximum output power
Open circuit voltage
Rated voltage
Short circuit current
Rated current
Elevation angles of 26o, 16o and 6o with an orientation angle
of 0o is shown in Figure 3. All the elevation angles provided
an output voltage of approximately 36 V for an open circuit
condition. Initial findings suggest that the PV panel provides
an output voltage (36 V) from about 6 am to around 8 pm.
This coincides with the manufacturing specifications shown
in Table 2.
Value
220 W
36.6 V
29.2 V
8.08 A
7.54 A
[1] EINSTEIN, A. 1879-1995. Albert Einstein quotes.
[Online]. Available at: http//www.phnet.fi/public/
mamma1/einstein.htm. Accessed: 2011-05-30.
[2] BOXWELL, M. Solar electricity handbook, a Simple
practical guide to solar energy-designing and Installing
photovoltaic solar electric systems. 2nd Ed. United
Kingdom: code green publishing, 2010, pp. 3.
[3] LOVEGROVE, K. & DENNIS M. Solar thermal Energy
systems in Australia. International journal of
Environmental studies. 63(6), 2006, pp. 791-802.
[4] FARRET, F. A. & SIMOES, M. G. Integration of
Alternative sources of energy. New Jersey: John Wiley
press, 2006, pp. 129.
[5] SALOUX, E., TEYSSEDOU, A. & SORINET, M.
Explicit model of photovoltaic panels to determine
Voltages and currents at the maximum power point.
Solar Energy. 85(5), 2010, pp. 713-722.
[6] WELMAN, KRUGER AND MITCHELL. Research
methodology. South-Africa: Oxford university press.
2005, pp. 146.
[7] SOLAR
WORLD.
[Online].
Available
at:
http://www.sustainable.co.za/solarworld-sunmodule220w-pv-module-solar-panel.html. Accessed:2011-0516
Asowata Osamede received his undergraduate degree in 2005
Figure 3. Different elevation angles against time for an open
circuit condition.
from Ambrose Alli University, Ekpoma, Nigeria. And he is
presently studying towards his Master degree in electrical
engineering at the Vaal University of technology. His research
interests include empirical testing of optimization models for
photovoltaic panel installations.