Academic Journal of Science and Technology 
ISSN: 2771-3032 | Vol. 10, No. 2, 2024 

 

121 

Enhancing	Heliostat	Field	Performance:	A	
Comprehensive	Study	on	Optical	Efficiency	and	Annual	
Thermal	Power	
Kunzheng Wang*, Yao Liu, Haolin Qin 

School of Software, Henan Normal University, Xinxiang, 453007, China 
*Corresponding author: 2228524051@stu.htu.edu.cn 

 

Abstract: The many advantages of solar photovoltaic technology make it bound to be commercially competitive in the coming 
years, and its development is strategically important. The parameters of the heliostat field, including the positional coordinates 
of the absorber tower, the size and mounting height of the heliostat mirrors, as well as the number and position of the heliostat 
mirrors, are designed according to the requirement of the rated annual average thermal power output of 60 MW so that the 
heliostat field will have the largest possible annual average thermal power output per unit of mirror area under the condition of 
reaching the rated power. Larger sizes and higher mounting heights of heliostats help to capture more solar energy and thus 
increase the annual average output thermal power per mirror area. The efficiency and output thermal power of heliostats of 
different sizes and mounting heights are evaluated by simulating the numerical calculation method and the best combination is 
found. 

Keywords: Transformation of the energy structure, Comprehensive utilization of solar energy, large resource utilization, 
Output thermal power. 

 

1. Introduction 
The establishment of new clean energy-led power systems 

is one of the key strategies for the transformation of the 
energy mix in developing countries [1]. The heliostat is an 
important basic concentrator unit in the tower-type 
photovoltaic power generation system, and its accuracy in 
tracking the sun and reflecting the sunlight directly affects the 
power generation efficiency of the whole photovoltaic power 
plant [2]. Firstly, the settlement is calculated by wind tunnel 
test and numerical simulation to compare the calculation 
results of simulation and wind tunnel [3]. The simulation 
results are in good agreement with the test results, fully 
verifying the reliability of the CFD simulation method used 
[4]. At the same time, in order to investigate the changes of 
the sun's azimuth and altitude angle, the date, geographic 
location and other data will be integrated into the matlab 
simulation software to obtain simulation results. In this work, 
we use the CFD simulation method model to build the model 
[5]. Data for this study was obtained from 
(http://www.mcm.edu.cn/) 

2. Fundamentals of A Fixed-sun 
Mirror Field 

2.1. Structure of the heliostat field 
As can be seen in Figure 1. The heliostat is the basic 

component for collecting solar energy in tower solar thermal 
power plants (hereinafter referred to as tower power plants), 
and its base consists of a Its base consists of a longitudinal 
rotating axis and a horizontal rotating axis, and the plane 
reflector is mounted on the horizontal rotating axis. The axis 
of the longitudinal rotary axis is perpendicular to the ground, 
which can control the azimuth of the mirror. The axis of 
horizontal axis is parallel to the ground, which can control the 
pitch angle of the mirror, and the heliostat and base are shown 

in Figure 1. The height of the intersection of the two axes 
(which is also the center of the heliostat) from the ground is 
called the mounting height of the heliostat. Tower Power 
stations utilize a large number of heliostats to form an array, 
called a heliostat field. Fixed sun mirror will reflect the 
sunlight convergence to the mirror field installed in the 
absorbing Collector mounted on the top of the tower, heating 
the heat-conducting medium, and the solar energy in the form 
of thermal energy storage, and then after heat exchange. The 
conversion of thermal energy into electrical energy is realized 
through heat exchange. Sunlight is not a parallel ray, but a 
conical ray with a certain cone angle, therefore , the reflection 
of the incident light from the sun at any point of the mirror is 
also a conical ray. When the heliostat works, the control 
system According to the position of the sun, the control 
system controls the normal direction of the heliostat in real-
time, so that the light emitted from the center of the sun is 
reflected by the center of the heliostat and pointed to the 
center of the collector. The center of the collector. The height 
of the center of the collector above the ground is called the 
height of the absorber tower. 

 

 
Figure 1. Schematic diagram of heliostat and base 

(https://baike.baidu.com/item/%E5%AE%9A%E6%97%
A5%E9%95%9C/9109957) 



 

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2.2. Determination of the optimal mirror field 
arrangement 

In the context of the rated power level of 60MW, if all the 
heliostats have the same size and mounting height, the 
following parameters of the heliostat field are designed: the 
positional coordinates of the absorber tower, the size of the 
heliostats, the mounting height, the number of heliostats, and 
the position of the heliostats, so that the heliostat field will 
have as large an average annual thermal power output per unit 
of mirror area as possible under the condition of reaching the 
rated power level. 

3. Results 

3.1. The establishment of the simulation model 
To simulate the variation of the sun's azimuth and altitude, 

the date and geographic location data are entered into the 
Matlab software to realize the simulation. 

3.2. Analysis of experimental results 
Figure 2 shows the distribution of the mean wind pressure 

coefficients on the surface of the heliostat for the wind tunnel 
test and numerical simulation with the elevation angle of the 

heliostat at 60° and the wind direction at 0°. Figure 3.10 
shows the distribution of the average wind pressure 
coefficient on the surface of the sidereal mirror for the wind 
tunnel test and numerical simulation at 60° elevation and 0° 
wind angle. In this paper, the average wind pressure 
coefficients are the net average wind pressure coefficients 
superimposed on the upper and lower surfaces of the structure. 

From the figure, it can be seen that the mean wind pressure 
coefficient of the mirror surface of the heliostat is 
symmetrically distributed at a 0° wind angle. The average 
wind pressure coefficients of wind tunnel test values range 
from 0.62 to 1.13, with the maximum value occurring at the 
lower center of the mirror and the minimum value at the upper 
center of the mirror. The maximum value occurs at the lower 
center of the mirror and the minimum value occurs at the 
upper center of the mirror. The results of the numerical 
simulation ranged from 0.73 to 1.14, and the distribution of 
maximum and minimum wind pressure coefficients was 
consistent with the test results. The distribution of maximum 
and minimum values of wind pressure coefficient is 
consistent with the test results. Comparing the results of the 
simulation and wind tunnel calculation, they are in good 
agreement, indicating that the simulation method is reliable. 

 

 
Figure 2. Distribution of mean wind pressure coefficients on the surface of the heliostat 

 
Figure 3 shows the distribution of the pulsating wind 

pressure coefficient on the surface of the heliostat mirror in 
the wind tunnel test and numerical simulation at an elevation 
angle of 60° and a wind angle of 0°. From the figure, it can be 
seen that the surface pulsation wind pressure coefficient of the 
heliostat gradually increases from the upper edge to the lower 
edge of the mirror under the wind angle of 0°, and is 
symmetrically distributed. The values of the pulsation wind 
pressure coefficient on the surface of the heliostat mirror in 
the wind tunnel test are between 0.26 and 0.43, and the values 
of the pulsation wind pressure coefficient in the numerical 
simulation are between 0.30 and 0.41, and the results of the 
two methods are in good agreement, and the distribution of 

pulsation wind pressure coefficient on the surface of heliostat 
mirror is in good agreement. 

The results of the two methods are in good agreement, and 
the distribution trends of the pulsating wind pressure 
coefficients are also consistent. Comparing the distribution 
patterns of the average wind pressure coefficient and the 
pulsating wind pressure coefficient on the mirror surface of 
the heliostat, it can be seen that the distribution patterns of the 
two are the same, with the minimum value appearing at the 
upper edge of the mirror surface and the maximum value 
appearing in the middle of the mirror surface at the lower 
position. 

 

 
Figure 3. Distribution of pulsating wind pressure coefficients on the surface of heliostats 

 
To simulate the sun's movement, we may take Baoding City, 

Hebei Province (38.873891°N,115.464806°E) as the target 
for simulation to study the changes of the sun's azimuth and 
altitude on September 22, 2020, and June 21, 2020, and input 



 

123 

the data of the date and the geographic location into the 
simulation program to obtain the simulation results. We take 
9:00 to 16:00 as the study period of a day to imitate the 
movement of the sun in a day, observe the simulation results 

every 15 minutes, record the simulation data, and input the 
data into MATLAB simulation to get the image of the change 
of altitude angle and azimuth angle in a day on the summer 
solstice: 

 

 
Figure 4. Summer solstice solar altitude angle azimuthal variation plot 

 
The data were integrated and fed into Matlab simulation to 

obtain an image of the change in altitude angle azimuth 
throughout the day on the fall solstice. 

 

 
Figure 5. Curve of variation of solar altitude angle azimuth on the fall solstice 

 
From Figure 4 and Figure 5, it can be seen that the sun's 

altitude angle is increasing and then decreasing throughout 
the day, and the altitude angle will reach its maximum value 
around noon, it can be seen from the data points in Figure that 
the rate of change of the angle is faster in the morning and 
afternoon, and the rate of change is more moderate around 
noon. From Figure 4 and Figure 5, the sun azimuth angle in a 
day was rising trend, has been increasing, and noon can be 
seen in the rate of change of the inflection point, that is, the 
maximum rate of change at noon, the summer solstice sun 
directly to the Tropic of Cancer, the equator on the autumnal 
equinox sun directly to the equator, due to the simulation site 
is located in the northern hemisphere, summer solstice 
sunshine time is the longest, the altitude angle and the angle 
of change than the autumn equinox is also more pronounced 
inflection point, the above data with The above data and 
change rule is in line with the actual movement of the sun, 
and can be used as an important data for the future reference 
of the position of the heliostat. 

4. Conclusions 
This paper provides a research idea and framework for use 

in the field of energy structure transformation, which helps to 
build a new energy modernization. At the same time, the 
simulation results are obtained by inputting the date, 
geographic location and other data into the simulation 
program, and 9:00 to 16:00 in a day as the research cycle to 
imitate the sun's movement trajectory in a day to get the 
simulation data, and then the data are integrated and inputted 
into the matlab simulation to get the change of altitude angle 
and azimuth angle images in a day. The above data and the 
rule of change are in line with the actual movement of the sun, 
and can be used as an important data for the future reference 
of the position of the heliostat. This paper explores this 
through wind tunnel wind tunnel tests and numerical 
simulations. From the above comparative analysis of wind 
tunnel test and numerical simulation results, it can be seen 
that the simulation results are in good agreement with the test 
results, and the reliability of the CFD simulation method used 
in this paper is fully verified. The feasibility of the method is 
demonstrated. 



 

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