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© Fraunhofer ISE

LONGTERM EXPERIENCE

WITH PV POWER PLANTS IN GERMANY

Dr. Christian Reise

Fraunhofer Institute for

Solar Energy Systems ISE

Freiburg, Germany

Solar Operations & Maintenance

Milan, October 9th, 2013

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The Fraunhofer ISE Quality Circle

Yield Assessments Module

Measurements

System tests

Quality

Monitoring

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What are the questions?

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What is the state-of-the-art performance of a PV power plant?

What about degradation?

What affects system reliability?

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A review of 20+ years of commercial PV systems in Germany


A study on 100+ power plants in Germany


Modules / inverters / operation management…

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PV support schemes in Germany

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Development of system Performance Ratio in Germany

A typical

5 kWp

system

installed

in 1993

within the

German

1000 Roofs

Programme

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Performance Ratio (PR): A simple Definition

PR =

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In Germany, state-of-the-art PV systems reach PR(si) values around 90%

Note the difference of some 3…4% between PR(si) and PR(pyr)

In southern Europe, PR will be reduced by 3…5%


Where is the limit?

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In Germany, state-of-the-art PV systems reach PR(si) values around 90%

Note the difference of some 3…4% between PR(si) and PR(pyr)

In southern Europe, PR will be reduced by 3…5%


Where is the limit?

PR =

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Modules show rated power

Maintenance of area

Theft protection

Minimized row to row shading

Important factors for successful projects

Lessons learnt

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Important factors for successful projects

Lessons learnt

Modules show rated power

Maintenance of area

Theft protection

Minimized row to row shading

Minimized local shading

Durable installation

QC with commissioning

Regular cleaning intervals

Monitoring of operation

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Data Handling

Filtering of 5-min average values:

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Data Handling


Irradiance between

800…1000 W/m²

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Data Handling


Irradiance between

800…1000 W/m²

Module temperature between

40…45 °C

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Data Handling


Irradiance between

800…1000 W/m²


40…45 °C

Values inside median ± 5%

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Data Handling


Irradiance between

800…1000 W/m²


40…45 °C

Values inside median ± 5%

Calculation of rate of change

rate in %/year

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Example: a German „1000-Roofs-Programme“ system

5 kWp PV system built in 1993

New monitoring equipment in 2001

outliers excluded

fitted linear slope

Rate of Change: ca. –0.3%/a

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-4.0%

-3.0%

-2.0%

-1.0%

0.0%

1.0%

2.0%

3.0%

4.0%mono/poly

1 2 3 4 5 6 7 8 9 10 11_

rate of change in % per year

years of operation


Results statistics for c-Si

Calculation of a rate of

change per year for each

PV system shows large

scatter

Average c-Si degradation

rates are around –0.25%

per year

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-4.0%

-3.0%

-2.0%

-1.0%

0.0%

1.0%

2.0%

3.0%

4.0% mono/poly

EFG/String Ribbon


Results for alternative silicon wafer technologies

1 2 3 4 5 6 7 8 9 10 11_

rate of change in % per year

years of operation

Average c-Si degradation

rates are around –0.25%

per year

Systems with EFG or

string-ribbon modules

reveal a tendency towards

larger negative rates of

change

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On average, there

are 5 incidents per

PV power plant and

year

Source:

meteocontrol,

Augsburg,

Germany

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Module reliability

BOS component & installation reliability

Operation management

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Module reliability

“no problem”


Commissioning tests


Monitoring & intervention concepts

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Commissioning tests

Detailed on-site analysis of the

entire power plant:

Comprehensive visual

inspection

Thermographic imaging

Measurement of actual PV

power and conversion to

Standard Test Conditions

Assessment of Performance

Ratio (PR)

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System Inspection and Testing

Verification of design data (module types, tilt angles, distances)

Screening for large and small anomalies (insufficient foundation,

cell grid faults)

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Mechanical problems

Faulty mounting of modules

Missing protection leading to cable damage

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Mechanical problems

Cable glands on top, moisture in the sub-distribution box

Spare cable glands not sealed, moisture and animals in the box

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Mobile lifting platform used

for infrared camera imaging

Temperature analysis of a

solar module with defective

cells

Temperature analysis of a

large module field


Infrared imaging

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Commissioning tests

Detailed on-site analysis of the

entire power plant:

Comprehensive visual

inspection

Thermographic imaging

Measurement of actual PV

power and conversion to

Standard Test Conditions

Assessment of Performance

Ratio (PR)

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Monitoring & intervention

Operation of a state-of-the-art supervisory control and data acquisition

(SCADA) system in each PV power plant

Operation of a dedicated control centre, offering all features needed to

evaluate system operation and to optimize maintenance work flow

Rapid reaction to error messages

Management, performing and documentation of maintenance and repair

On-site visits in regular intervals

Landscape maintenance

Learn more about operation management at this event…

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Conclusions…

PV power plant operation is well understood and reproducible

Today’s systems may reach PR(si) values around 90% in Central Europe

Mono- and polycrystalline silicon systems show small degradation rates, by

default, Fraunhofer ISE assumes –0.25% per year

Long term success starts with a comprehensive system testing

Only professional O&M concepts ensure high performance and yields

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Thank you for your attention!

Fraunhofer Institute for Solar Energy Systems ISE

Dr. Christian Reise

[email protected]

www.ise.fraunhofer.de

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