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Increasing the efficiencies of solar energy conversions

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richa agrawal

on 3 November 2015

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Transcript of Increasing the efficiencies of solar energy conversions


Useful energy conversion
Solar Energy Conversion
Solar PV Panel

PV power drops linearly excess of 25C
open circuit voltage (VOC) decrease and the short circuit current (ISC) increase
current has as a linear relation to the intensity of sunlight which is un-controlable
this sun-shine also causes heat which results in voltage drop; heat can be controlled
Available solar energy
Dr Chandra Shekhar Malvi
Associate professor & Head
Mechanical Engineering Department
Madhav Institute of Technology & Science, Gwalior
e-mail: csmalvi@gmail.com
Mb: 999 320 7600

Sun gives
444 kTWh

Per day

We need
132 kTWh

Energy Research
Solar Thermal Collector
Solar Photovoltaic Panel
Thermal Energy
Electrical Energy
Ref: Ron Curts&MrSolar.com
Temperature effect on PV panel
Ref:(c) Damon Hart-Davis
Temperature effect on PV panel
Ref.: Sharp, 2009

PVT/Air panel with thin metal sheet and metal fins
(Tripanagnostopoulos and Themelis, 2009)

Air Cooling of PV panels
a) Leaky tube (Kordzadeh, 2010) b) Nozzles (Krauter, 2004)

Water Cooling of PV panels
Water thin film


Water Cooling of PV panels
c) Spraying by pump (Abdolzadeh and Ameri, 2009),
d) Submerging in water (Rosa-Clot et al., 2010a)


Excess heat
Exploitation of heat
PV panel

Solar collector

This is called Photovoltaic thermal (PVT) technology
CHAPS-combined heat and power solar (Coventry, 2005)

PVT prototypes with packing factor a) 50%, b) 63% (Chow et al., 2007)

Photovoltaic thermal (PVT) technology
Ref: characolumbus

IPVTS -integrated PVT system
(Huang et al., 2001)

PVT technologies
Releases heat (discharging)

Stores heat (charging)



A phase change material (PCM) is a substance with a high latent heat of fusion. PCM stores and releases the heat during phase change.

Changes of state in water (Kaygusuz, 1995)

SolarNor collector with granulates
(Sandnes and Rekstad, 2002)
PCM filled solar water heater
Theory of PVT-PCM technology
Principle of PVT-PCM system
Schematic of PVT-PCM collector
Modeling and Simulation
A schematic cross-sectional view of PVT/PCM collector

Thermal network

PCM thermal parameters
Simulation results
PCM performance
Function of depth

(a) phase and (b) temperature of PCM as a function of the depth in PCM layer over a 24h period

PCM performance
PCM Performance
Function of melting point and conductance
PV and Thermal performance/ PCM melting point

PV and Thermal performance/ conductance of PCM

Objectives of PVT-PCM panel
Candidate PCMs
PCM :Selection criteria
It fulfills the criteria 1
Effects negatively -1
Properties not applicable 0
Fabrication : Modification approaches
PV panel
is modified

Thermal collector is modified

Dish PVT Collector
PV cells cannot be adhered on to a curved surface
PCM collects at the bottom creates a misbalance in the collector
PV cells do not work at such a high surface temperature
Thermosiphoning is not effective in curved tubes or a high angle of tilt
the reflective dome was not be developed.

Prism Solar PVT-PCM panel
a) Schematic of solar prismatic PVT-PCM panel b) HPC module (Stone Ridge Technologies)
*HPC = Holographic Planar Concentrator™

…was not available so Flat Plate collector is considered for testing

FP-PVT collector
Schematic cross-section

Schematic of PVT-PCM collector

Fabrication of FPC-PVT collector
a)Copper sheet



b) water tube -in-PCM tubes
c) Tube-in-tube work sandwiched in absorber sheet
d) Box with insulation and reflecting surface
e) Absorber sheet placed collector tray
f) glass top on collector box
Heat removal factor
Serpentine Flow

A quantity which relates the actual useful energy gain of a collector to the useful gain if the whole collector surface were at the fluid inlet temperature
Parallel Flow

PCM filling practices
Spiral flow in tube-in-tube

Serpentine flow with PCM bag

Recommended for future work
Experimental Set-up
Observations: FP-PCM collector
inconsistent data due to weather problems –forced to the indoor testings
ASHRAE standards mainly focuses on solar water heating system but not on PV or PCM
Filling PCM in the pipe problem - moved to channel type arrangement
PV cells pasting on irregular absorber plate surface problem- moved on PC sheet for flat surface
The temperature on the absorber plate was too high (~90C) which is harmful for PV cells
However, PV on glass cover are recommended
The phase change could not be seen in the metallic tube – some transparent medium
thin layer of PCM in the tube-in-tube arrangement-optimally thick layer is recommended
Temperature profiles of FP-PVT collector with OM 56 PCM

Modifying a commercial PV panel

Schematic cross section of PVT panel

Observations : PVT-PCM panel
Results: PVT-PCM panel
Cell temperature and Electrical efficiencies

Variable heat removal factor in PCM

Results: PVT-PCM panel
with PCM OM46
4 kg/hr can be a maximum mass flow rate when Fr is 0.74
variable values of Fr from 0 to 0.28 are obtained.
Mass flow rate: PVT-PCM panel
target hot water temperature is 40C
expected thermal efficiency 50% (PVT)
In total 105 kg/m2 hot water per day can be collected which is comparable to Huang PVT system with 81 kg/m2 (Huang et al., 2001).
Summary of results : modified panels
Manufacturing aspects
FP-PVT collector is feasible and simple to fabricate, however, PCM bags needs to be explored
Thermal combination of PV cells and a thermal absorber plate can be achieved by using polymer lamination. However, the life span of lamination is yet to be observed.
PVT-PCM is also feasible, however, an accessory kit is recommended.
Electrical insulation can be achieved with both approaches; PVT collector and PVT panel,
Dish PVT Collector can be fabricated of a smaller version

PCM integration

good thermal contact is achieved, however, metal-in-metal tube arrangement is recommended
the PCM integration can increase the reliability in the no-sunshine period.
thickness of the PCM needs to be optimised
PVT-PCM gives approximately 15% electrical efficiency with 40oC temperature of water
PVT-PCM gives a variable heat removal factor which depends on the phase-change duration
It is still necessary to find a more suitable bag or metallic tube to fill PCM; with either a serpentine or parallel arrangement of the water tubes

Recommendations: PVT-PCM panel
…moved to a uniquely designed PVT panel

a uniquely designed PVT panel
To use wall-to-wall parallel flow which provides a greater heat removal factor in comparison to the serpentine or spiral flow.
To utilise a non-metallic thermal absorber
To directly encase the solar cell with polycarbonate substrate
To identify a suitable PCM as per location, in this case the UK and India
To observe the temperature profile while water is circulating through due to gravity flow
To include the packing factor performance assessment

Polycarbonate PVT-PCM panel
Polycarbonate PVT-PCM panel (PC-PVT-PCM)
Previous approach

New approach

Methodology: PC-PVT-PCM
Experimental: PC-PVT-PCM
…empty channel also can be used a air-heater

Efficiency: PC-PVT-PCM
easy fabrication and economic

Recommended : PC-PVT-PCM
Polymer PV panel
Solar panel

Solar photovoltaic panel
Objectives of PV encasement
To study and identify the polymer encasement material for photovoltaic panel
To fabricate the PV panel in the laboratory and optimize simple and feasible techniques locally in India
To test performance characteristics of fabricated PV panels
To analyze various environmental factors such as sunlight, dust and rain
To develop and install a complete ready to use LED lighting PV system

Ref: Solar Energy Materials and Solar Cells, 90, 2006

Fabrication of a PV panel
Encapsulation practices
TPT failure due to lack of adhesive

PET successful lamination

Double heat stroke

PET encapsulation for two cells

Lamination of PET/Cell/TPT/PET

Lamination of PET/Cell/EVA/PET

Ironing of PET/Cell/EVA/PET

Ironing PET/Cell/EVA/PC


Preparation of panels
Experimental setup
Results: PV Panels 1-3
Panel 2 has the maximum peak time power followed closely by panel 3 and then panel 1

Highest efficiency gained of 10% by panel 2 and the lowest of 4% by panel 1

Results: PV Panels 1-3
Panel 1 degraded slowly over the time

Panel 3 uses the novel assembly of PET and PC around the solar cell

Data logging circuit on ProfiLab

Effect of dust on PV
Dust density
Microscopic images shows the dust agglomeration in 1mmx1mm area

Dust density contd...
Histogram shows the distribution of various size of dust particles collected on the samples

Reduction in transmittance
About 15% transmittance is reduction in 7 days
Water cleaning recommended every third day

PET transmittance reduction of about 23% in 1 month, therefore not recommended
PC transmittance fluctuates approximately 4% for two months, which is considerable but recommended

By dust

By sunlight: colour index

Installation: Conclusion
PV-LED unit
Gwalior municipal corporation
is interested to establish a
small plant

Skill developed
Solar Photovolatic Panel
Material selection for solar cell lamination and encasement such as PET, EVA, TPT, PC etc.
Performance analysis; electrical, structural and mechanical
Planning a cleaning schedule due to dust
Planning a thermal management system
Designing a solar PV-T system by modifying PV panel using water and PCM
Fabrication of nanocrystal test bed using electro-deposition method to using TiO2/Cu or Ag

Posters presented in conferences

Future Research
Specific and major requirement
Solar Simulator
TRYSNS software
200 sqft area for plant

Thank you
Any question, please ?

Ref.: Sharp, 2009

Solar photovoltaic thermal air collector
(Jin et al., 2010)
a) Leaky tube (Kordzadeh, 2010) b) Nozzles (Krauter, 2004)
Ref: characolumbus

PVTWINS, Netherlands

Commercial PVTs
Latent Heat Storage
About 15% transmittance is reduction in 7 days
Water cleaning recommended every third day

PET transmittance reduction of about 23% in 1 month, therefore not recommended
PC transmittance fluctuates approximately 4% for two months, which is considerable but recommended

We do not inherit the earth from
our parents,
we borrow it from
our children

Chief Seattle
Duwamish(c. 1786 – 1866)
Problem and Solution Approaches
Installation, observations, reults etc.
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