This Research Project was presented at The International Conference on Renewable, Applied and New Energy Technologies 2018

1. ANTI-SOILING COATING OF
SOLAR PANELS TO INCREASE
THEIR EFFICIENCY
Project Members:
• Dr. Saim Saher
• Dr. Rizwan M. Gul
• Waleed Hassan
• Muhammad Shaheer
• M. Sabah Ud Din Ersum

2. INTRODUCTION
• Dust accumulation on the protective glass of photovoltaic (PV) panels gradually
decreases the power output especially in many cities of Pakistan due to the dusty
environment
• The transmittance of sunlight through the glass of solar panel can be reduced by
90% in a single month due to dust deposit, this phenomenon is also known as
soiling effect
• To overcome this problem, a hydrophobic coating by sol-gel process is
indigenously prepared and coated on solar panel glass

3. PREPARATION OF HYDROPHOBIC COATING
• The hydrophobic coating is prepared by SOL-GEL process
• SOL-GEL is a process in which solid Nano particles dispersed in a liquid (a sol),
interconnected together to form a continuous three dimensional network
extending throughout the liquid (a gel)
• In our case the solid Nano particles were silica Nano particles which are prepared
by using Stobers Method

4. STOBERS METHOD
• In material science, Stobers process with high concentration of tetra-
ethyl-orthosilicate (TEOS) up to 1.24M is used to prepare
monodisperse particles
• Silica nanoparticles are prepared by hydrolysis and condensation of
TEOS in ethanol, and in the presence of ammonia solution as catalyst
• The size of silica particles increases with increasing TEOS and
ammonia concentrations where both the rate of hydrolysis and
condensation become faster

5. 30
275
403
680
783
820
860
930
0
200
400
600
800
1000
0.22 0.45 0.56 0.67 0.75 0.9 1.115 1.24
Particlesize(nm)
TEOS CONCENTRATION (MOLE)
MOLE RATIO = TEOS: Ethanol: Ammonia: Water
• 0.28: 17: 0.81: 6.25
• 0.35: 17: 0.81: 6.25

6. SEM IMAGES of silica Nano particles

7. Preparation of Silica Solution
Ethanol Ammonia Solution TEOS Silica Solution
Mole Ratio
TEOS: Ethanol: NH3: H20
TEOS vol.% Ethanol vol.%
Ammonia Sol. 32% concentrated
vol.%
Deionized H2O vol.%
0.28: 17: 0.81: 6.25 5.28 83.92 4.01 6.78
0.35: 17: 0.81: 6.25 6.51 82.83 3.95 6.69

8. Adjustment of PH
Then the pH of silica solution was lowered from 8 to 3
by adding oxalic acid to increase the rate of hydrolysis
and condensation reaction that occurs in a solution
between TEOS and ethanol

9. Addition of APTEOS
• After preparing silica solution a few drops
of 3-Aminopropyl)Triethoxysilane APTEOS
(0.1 vol. %) was added, which acts as an
aggregating agent to form the silica Nano-
particles network
• The APTEOS modified silica sol was
denoted as AP-sol

10. Cleaning of Glass
• Transparent glasses were used as substrate
• The glass substrates were cleaned in sulphuric acid for
15 min to remove the contaminated surface

11. Dipping in AP-Solution
• The cleaned substrates were immersed into the
AP-solution for 5 minutes

12. Solidification of AP-Sol coating
• The coated substrates were annealed at 150 °C for 1 hour in order to
solidify the Nano-coating

13. HDTMS Sol Preparation
• Hexadecyltrimethoxysilane (HDTMS) (2 vol. %) is mixed with ethanol (96 vol. %)
and deionized water (2 vol. %)
• The AP-sol substrates were immersed in HDTMS solution for 30 min at 50 °C to
further to increases roughness which helps in gaining hydrophobicity
• The coated samples were annealed at 150 °C for 90 min to improve the bonding
characteristics

14. Contact Angle
• Static contact angle of Nano coated substrates is measured using IMAGEJ software
• If a water drop has a tendency to stick to itself more than it sticks to a given
surface that surface is called hydrophobic and the water drop will bead up with a
contact angle greater than 90°

15. Atomic force microscopy Test
AFM of 0.35 M TEOS AP-solution coated substrate
2D AFM image 3D Atomic Force Microscopy image Height profile curve of AP-sol nano-
coating

16. Atomic force microscopy Test
AFM of 0.35 M TEOS HDTMS solution coated substrate
2D AFM image 3D Atomic Force Microscopy image Height profile curve of HDTMS-sol
coating

17. Atomic force microscopy Test
Roughness parameters AP-sol Nano Coating, nm HDTMS Solution coating, nm
Ra 2.80 3.85
RRMS 3.20 4.70
Rz 17.7 22.9
Surface roughness of AP-sol Nano Coating and HDTMS-sol coating
• Ra= the arithmetic average value of filtered roughness profile determined from deviations about
the center line within the evaluation length, i.e. the average of peak height and valley depth
• RRMS= root mean squared
• Rz= the distance between the top profile peak line and the bottom profile valley line on sampled
portion= maximum height of the profile

18. SPECTROPHOTOMETER TEST
0
10
20
30
40
50
60
70
80
90
100
300 350 400 450 500 550 600 650 700 750 800
Transmittance(%)
Wave length (nm)
Transmittance Vs Wavelength
0.28 M TEOS
0.35 M TEOS
Un-coated Substrate

19. SPECTROPHOTOMETER TEST
The transmittance of coated and uncoated substrates in three visible wavelengths
Samples
Concentration of
TEOS
Transmittance (%)
400 nm 550 nm 700 nm
0.28 M 72.65 74.65 72.49
0.35 M 73.88 75.07 72.47
Uncoated Substrate 89.82 90.48 86.93