The document discusses the development and reliability of photovoltaic systems at the Technological Educational Institute of Crete, focusing on solar radiation, photovoltaic generation forecasting, and performance measurements. It emphasizes the importance of high voltage insulation systems and pollution effects on power outages, along with the implementation of composite materials to enhance network reliability. It concludes that PV generation is promising for power generation in Crete and highlights the need for full-scale grid optimization for reliable operation.

1. S C H O O L O F A P P L I E D T E C H N O L O G Y
Laboratory of Energy and Photovoltaic Systems
Technological Educational Institute of Crete
Developing
reliable photovoltaic
and outdoor high voltage
systems

2. Photovoltaic
Park
CENTER OF ENERGY AND PHOTOVOLTAIC SYSTEMSTEI OF CRETE
Laboratory of Energy and Photovoltaic Systems
Electrical
Discharges
Lab (EDL)
Laboratory of Energy and
Photovoltaic Systems
(LEPS)

3. Photovoltaic
Park
CENTER OF ENERGY AND PHOTOVOLTAIC SYSTEMSTEI OF CRETE
Electrical
Discharges
Lab (EDL)
TEI OF CRETE

4. Photovoltaic
Park
CENTER OF ENERGY AND PHOTOVOLTAIC SYSTEMSTEI OF CRETE
Electrical
Discharges
Lab (EDL)
Photovoltaic
Park
TEI OF CRETE

5. TEI OF CRETE
Field of expertise:
0
200
400
600
800
1000
1200
04:48:00 AM 07:12:00 AM 09:36:00 AM 12:00:00 PM 02:24:00 PM 04:48:00 PM 07:12:00 PM 09:36:00 PM
SolarRadiation(W/m2)
Sunny
Cloudy
1. Solar Radiation

6. TEI OF CRETE
Field of expertise:
1. Solar Radiation
2. Photovoltaic Generation
 PV module performance measurements,
• field testing bay – simultaneous
operation of different technology PVs
• degradation of PV performance
0 5 10 15 20 25 30 35
165
170
175
180
185
190
195
Δθ (degrees Celcius)
Power(Watts)

7. TEI OF CRETE
Field of expertise:
1. Solar Radiation
2. Photovoltaic Generation
 PV module performance measurements,
• field testing bay – simultaneous
operation of different technology PVs
• degradation of PV performance
• testing and measurement equipment
developed in our lab

8. TEI OF CRETE
Field of expertise:
1. Solar Radiation
2. Photovoltaic Generation
 PV module performance measurements,
 PV power modeling

9. TEI OF CRETE
Field of expertise:
1. Solar Radiation
2. Photovoltaic Generation
 PV Panels testing and efficiency,
 PV Panels modeling
 Solar tracking
Novel Tracker
(Two axis motion with a single motor)
A highly efficient novel Azimouthal
heliotrope. Mayromatakis F. and Y.
Franghiadakis
Solar Energy. V82, Issue 4, April 2008,
Pages 336-342
Modified Polar Tracker

10. TEI OF CRETE
Field of expertise:
1. Solar Radiation
2. Photovoltaic Generation
3. PV applications

11. TEI OF CRETE
Field of expertise:
1. Solar Radiation
2. Photovoltaic Generation
3. PV applications
4. Grid integration – high voltage networks
 PV generation forecasting,
 Operation in high voltage distribution networks
 Operation and reliability of high voltage distribution networks
 Outdoor high voltage insulation systems
 Implementation of composite HV insulation materials
 Field testing

12. TEI OF CRETE
PV generation in Crete:
The Power System Of Crete
 The largest isolated power system in Greece
 Load factor

13. TEI OF CRETE
PV generation in Crete:
STEAM
TURBINES
20%
GAS
TURBINES
32%COMBINED
CYCLE 12%
DIESEL
GENERATORS
14%
WIND
GENERATION
16%
PV
GENERATION
6%
The Power System Of Crete
 The largest isolated power system in Greece
 Load factor
 Installed generation
 Total installed power generation
1091MW
Wind Farms 180MW
 PV Generation 70MW
63MW Field PV Parks (800X ≈80kW)
7MW roof installed PV generation

14. TEI OF CRETE
PV generation in Crete:
The Power System Of Crete
 The largest isolated power system in Greece
 Load factor
 Installed generation
 Total installed power generation
1091MW
Wind Farms 180MW
 PV Generation 70MW
63MW Field PV Parks (800X ≈80kW)
7MW roof installed PV generation
 Small PV generation
installations
 Connected to the 20kV
or 400V network
 Distributed in Crete
STEAM
TURBINE
S 20%
GAS
TURBINE
S 32%
COMBINE
D CYCLE
12%
DIESEL
GENERAT
ORS 14%
WIND
GENERAT
ION 16%
PV
GENERAT
ION 6%

15. TEI OF CRETE
PV generation in Crete:
The Power System Of Crete
 The largest isolated power system in Greece
 Load factor
 Installed generation
 Annual peak load during the summer
 Daily two peak loads at 12:00 – 13:30 and 17:00-21:00

16. TEI OF CRETE
PV generation in Crete:
First concern: generation forecasting
PV generation (sunny days)
Tracker
Fixed
During the summer:
 The period of optimum performance coincides
with the period of maximum demand,
 The daily peak load coincides with the peak
generation of PVs,
 Considering that cloudy days are not often
during the summer, PV generation can be
predictable for the system operator,
 Small variations are usually eliminated due to
the distribution of PV installations,
 Benefits for the network
But
 There is a strong dependence of the PV
generation reliability to the network reliability
 The system operators demands reliable
estimation tools for the PV generation

17. TEI OF CRETE
PV generation in Crete:
First concern: generation forecasting
PV generation (cloudy days)
Cloudy
Sunny
In the case of cloudy days:
 During cloudy days there are large variations on
the PV generation of each installation,
 In a total these variations are eliminated by the
geographical dispersion of the PV installations

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PV generation in Crete:
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20
30
40
50
60
70
6:00 8:24 10:48 13:12 15:36 18:00 20:24
CHANIA
CHANIA
PV generation 18 - 09 - 2012

19. TEI OF CRETE
PV generation in Crete:
0
10
20
30
40
50
60
70
6:00 8:24 10:48 13:12 15:36 18:00 20:24
RETHYMNO
RETHYMNO PV generation 18 - 09 - 2012

20. TEI OF CRETE
PV generation in Crete:
0
10
20
30
40
50
60
6:00 8:24 10:48 13:12 15:36 18:00 20:24
IRAKLION
IRAKLION
PV generation 18 - 09 - 2012

21. TEI OF CRETE
PV generation in Crete:
0
10
20
30
40
50
60
70
6:00 8:24 10:48 13:12 15:36 18:00 20:24
LASITHI
LASITHI PV generation 18 - 09 - 2012

22. TEI OF CRETE
PV generation in Crete:
0
10
20
30
40
50
60
70
6:00 8:24 10:48 13:12 15:36 18:00 20:24
CHANIA
RETHYMNO
IRAKLION
LASITHI
PV generation 18 - 09 - 2012

23. TEI OF CRETE
PV generation in Crete:
0
10
20
30
40
50
60
70
6:00 8:24 10:48 13:12 15:36 18:00 20:24
CHANIA
RETHYMNO
IRAKLION
LASITHI
AVERAGE
PV generation 18 - 09 – 2012
In an average
How can we reliably operate a fleet of PV generation units and
further predict the short term and long term generation.

24. TEI OF CRETE
PV generation in Crete:
1. The total PV generation variation is improved in quality as more
PV plants are connected,
Is this useful for the system operator?
It is not enough, more information is required
2. There is a large number of generation points to monitor
Determine criteria to select a representative group of generation points to be
monitored,
3. Are we interested only for the PV generation?
No, for example voltage stability of 20kV lines is also a critical point
4. Is the network influencing the PV generation
Certainly, the HV network becomes a critical component of the equivalent
“PV Generator” . Transmission line outages are more frequent as the HV network
of interest geographically expands, thus can alter the “PV Generator” reliability.
5. Primary cause of transmission line outages in Crete is a phenomenon called
“Pollution of HV insulators”

25. TEI OF CRETE
Outdoor HV Systems:
Pollution of High Voltage Insulators
 Development of surface conductivity on the surface of High Voltage
insulators,
 Result of the water dissolution of sea salt deposition,
 Capable of resulting to the total loss of insulation.
 Primary cause of power outages in Crete
0
20
40
60
80
100
120
140
160
Faults
Pollution

26. TEI OF CRETE
Outdoor HV Systems:
Pollution of High Voltage Insulators
 Development of surface conductivity on the surface of High Voltage
insulators,
 Result of the water dissolution of sea salt deposition,
 Capable of resulting to the total loss of insulation.
 Primary cause of power outages in Crete
Present during the summer Fortunately appears during the night

27. TEI OF CRETE
Outdoor HV Systems:
Pollution of High Voltage Insulators
 Development of surface conductivity on the surface of High Voltage
insulators,
 Result of the water dissolution of sea salt deposition,
 Capable of resulting to the total loss of insulation.
 Primary cause of power outages in Crete

28. TEI OF CRETE
Outdoor HV Systems:
Pollution of High Voltage Insulators
Pollution of HV insulators cannot have a direct influence on PV
generation, however in Crete has considerable impact on the reliability
of the HV network.
Is there a solution?
The use of composite hydrophobic materials, insulators or coatings

29. TEI OF CRETE
Outdoor HV Systems:
Pollution of High Voltage Insulators
Pollution of HV insulators cannot have a direct influence on PV
generation, however in Crete has considerable impact on the reliability
of the HV network.
Is there a solution?
The use of composite hydrophobic materials, insulators or coatings

30. TEI OF CRETE
Outdoor HV Systems:
Pollution of High Voltage Insulators
Talos Testing Station (www.talos-ts.com)
T.E.I. of CreteP.P.C. S.A.
University of
Patras
At Linoperamata Crete

31. TEI OF CRETE
Outdoor HV Systems:
Pollution of High Voltage Insulators
Composite materials have been implemented in the 150kV
network of Crete, for more than 10 years
Outages due to pollution have been eliminated
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
(Number of Polution faults to total) %

32. TEI OF CRETE
Outdoor HV Systems:
Pollution of High Voltage Insulators
Composite materials have been implemented in the 150kV
network of Crete, for more than 10 years
Outages due to pollution have been eliminated
 It is necessary to incorporate this solution to the 20kV network
20KV TALOS TESTING BAY

33. TEI OF CRETE
In conclusion:
1. PV generation is a very promising technology for power
generation and Crete is an ideal place to be implemented
2. CEPS is formed in an effort to bring together people working
in the fields of RES and Power Systems, aiming to optimize the integration of PV
generation in Power High Voltage Distribution Systems
3. Crete is today the best possible case study for RES and distributed generation
systems.
4. Full scale grid optimization is required to achieve a reliable operation of a
distributed “PV generator “
5. High voltage insulation is a critical parameter for the reliability of high voltage
distribution system.
6. The improvement achieved by the use of composite insulation in
HV networks has been proved in the environment of Crete