The photovoltaic panels and DC installation, connecting the panels with the inverter, are among the most important components of each photovoltaic power plant. Their flawless functioning and effectiveness are the major factors, determining the quantity of the generated power and the return of investments. In order to ensure such reliability only high-quality materials – PV panels, cables, connectors, etc. have to be used and all construction and assembly works have to be performed with necessary preciseness and responsibility. But even this can not guarantee to the company, running the power plant that the system will operate with its planned effectiveness for a long period of time without carrying out checks and repairs. It is always possible some section of the power plant to get out of order. Such power plants have open-air installations and are exposed to the whims of weather to a larger extent, as compared with many other power installations. In order to ensure an effective functioning of the power plant during the entire period of its utilization and facilitate its initial putting into operation and subsequent maintenance NATURELA offers integration of a string level monitoring system - PV-SCTL3. This system provides clear and timely information about the status of the entire generating section of the power plant, from the PV panels to the inverter. The system modules measure the current and the voltage of each string, and the obtained results are processed and sent to a data concentrator for storage and analysis. The system monitoring both the status and operation of the PV panels, and the whole DC installation, consisting of many cables, links, connections, string boxes, etc.

In order to operate effectively the PV power plant it is necessary to maintain each PV panel in its best possible condition. The price of such power plants is too high, especially when taking into account their low effectiveness, so nobody can afford to lose power as a result of untimely service. This is of great importance for large PV power plants, having thousands of panels and operating with central inverters. Without such system for diagnostics and monitoring it is not possible to ensure that all PV panels and cables are in a perfect condition and produce maximal possible power.

The Monitoring System in a PV power plant, offered by NATURELA has additional advanced features:

• It provides trusted detailed information about the power generated by each string of PV panels.
• It provides information about fault in PV panels in each strings. Such information is accompanied by a light indication, visible both from the central server and the string box.
• Upon occurrence of a fault in the power plant the system gives clear and visible reference points of the place, where the fault is registered and the fault nature.
• It makes an analysis of overshadowing of the strings.
• It monitors the status of fuses of each strings.
• It provides information about occurrence of a serious current leakage or a short circuit in the cables of the strings.
• Full self-diagnostic of each measuring module.
• The mounting of the system is easy and quick. No need of additional cabling for power supply and data transmission. The measuring modules are mounted in the Combiner Box, powered from current generated by the PV panels and have wireless connection with the server.
• User friendly software.

Technical data:

• Number of terminals for separate strings - 15
• Range of measured current - +/-10А
• Method of current measuring - by shunt resistor 0,01 Ohm
• Max. operating voltage - up to 1000V DC
• Measurement accuracy - +/-1%
• Power supply range - 30 - 1000VDC (start from 200VDC)
• Consumed power - мах 2.5W
• Radio-modem frequency - 868MHz
• RF output power - 10dBm
• LED indicators - 17
• Isolated serial interface for diagnostics and upgrading
• Dimensions of the PCB - 180х95mm

Software

Measuring module included in the system are depicted as rectangles on the map of the terrain of the plant, the color of the rectangle indicates the status of the module. Thus the operator can easily understand the state of the whole plant and the location of the problematic components.

 

The program allows showing oscillograms with measured parameters in real time for the selected measuring module.
 

Panel to display information for the current module contains the name of the measuring module, indicators for module inputs and four pages - Status, Measure, Power Meter and Shading Loss. Indicators of inputs of the module signal string generating less energy than others. Status page contains the latest available status of the module, the parameters that are outside acceptable limits are displayed in red.

Measure page contains the latest available information on measured parameters of the module, which includes a diagram of the instantaneous power of the inputs, calculated from the measured input voltage of the module and the input current.
 

Power Meter page contains a chart with total generated power and generated power from last reset.
 

 

Page Shading Loss

 

The program automatically receive information from all measuring modules included in the system. Based on the already received information make various reports and charts.

 

Daily generated energy.




Generated power for every strings.


Power plant total generated power
 

 


The megawatt scale photovoltaic power plants with PV-SCTL3:

1.Yankovo:

Capacity: 2.4 MWp
PV Modules: Thin-film
PV-SCTL Modules: 321 units (15 strings/unit)

 
2. Devnya North Hill

Capacity: 1.7 MWp
PV Modules: Thin-film
PV-SCTL Modules: 228 units (15 strings/unit)

 
3. Devnya Center Hill:

Capacity: 1.8 MWp
PV Modules: Crystalline
PV-SCTL Modules: 42 units (10 strings/unit)

 
4. Devnya South Hill:

Capacity: 1.3 MWp
PV Modules: Crystalline
PV-SCTL Modules: 30 units (10 strings/unit)

 

5. Malko Turnovo:

Capacity: 2.4 MWp
PV Modules: Thin-film
PV-SCTL Modules: 330 units (15 strings/unit)

 

6. Strazhitsa:

Capacity: 1 MWp
PV Modules: Thin-film
PV-SCTL Modules: 62 units (15 strings/unit)

 
7. Elshitsa:

Capacity: 1.15 MWp
PV Modules: Crystalline
PV-SCTL Modules: 18 units (6 strings/unit)

 
8. Chobanka:

Capacity: 1.25 MWp
PV Modules: Crystalline
PV-SCTL Modules: 36 units (6 strings/unit)