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Example Project „Technical DD“ of a Solar Power Plant in South Italy
mandate: Check the power plant on technical conformity, design, maintenance status and performance.
Main figures of the power plant:
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Photovoltaic Installation
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example
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nominal powerDC
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999 kW
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nominal power AC
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979 kW
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Module supplier
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Renewable Energy Corporation REC
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type
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160 REC 240 PE / 3'920 REC 245 PE
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power per module
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240 - 245 W
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number of modules
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4’080
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inverter supplier
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Refusol
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type
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Refusol 20 K
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power per inverter
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19.2 kWAC
19.6 kWDC
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number of inverters
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51
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producer of structure
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H. Kühling Stahl- und Metallbau GmbH
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- check of inverter dimension
- check of cable dimension
- check of the design of the power plant (like stringing, shading angle, inverter dimension etc.)
- analyze of the security system
- check of the structural stability
- check of the production
Ill. 1: view of the structure
executed on site works
- visual check of all components
- check of the installation quality
- check of the modules
- check of the string currents
U-I-curve measurement on a selected number of strings
results of the analyze
The power plant has been assessed to be good, with some minor reserves
Check of the modules
The U-I-curve-analyze has shown a good result for the solar modules
ill. 2: sample of IV-curve measurement
The measured power on site was just 5% below nominal power. This result can be considered as being good, the curves had a good shape.
The main weak point of this installation was DC cabling below the modules. We made haere a reserve ans asked for improvements.
ill. 3: insufficient cabling
ill. 4: inverters
The only reserve for the inverters was the exposition of the displays towards sun. The displays were subsequently covered by plastic sheets. We have also registered the regular failure of inverters without being able to find the reason.
The security system has been assessed as being too weak (addendum: unfortunately confirmed through a modul theft two years later).
ill. 5: camera pole
Unfortunately, our assessment of the security saytem has been approved by a theft of solar modules.
Analyze of the production
The available data have been carefully analyzed
ill. 6: comparison of the inverters
comments:
ill. 7: monthly performance
Forecasted yield of production : 145‘000 kWh/a
Registered yield (normalized on a average year): 150‘000 kWh/a
The power plant is productin better than expected.
We gave the advice to the investor to purchase the power plant, but requested some minor improvments.
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