Irradiance Sensor With Modbus RTU Output
It’s a Sensor Box for Solar PV Plants having a Modbus RTU Output. Besides Irradiance Sensor, it includes also an Internal Cell Temperature Sensor.It is compatible with all Modbus RTU Dataloggers. It is supplied along with Mounting Bracket and Cable.
MODE OF OPERATION
A silicon solar cell can be used as an irradiance sensor, because the short-circuit current is proportional to irradiance. Our sensors are built out of a monocrystalline solar cell connected to a shunt. Due to the low resistance of the shunt the cell operates next to short circuit.
The temperature coefficient of the short-circuit current creates a small error. The compensation is realized by using a specific temperature sensor laminated to the rear side of the solar cell. The measuring signals of short- circuit current of the cell and the resistance value of the temperature sensor are measured by a micro controller. The calculated values of irradiance and temperature given onto a RS485 port with customer specification protocol. The electronic circuit is optimized for low power consumption.
The solar cell is embedded in Ethylene- Vinyl- Acetate (EVA) between glass and Tedlar. Plain integration into the top cover of the box Advanced weatherproof junction box made of UV resistant material with cable gland and screw-less terminal for the connection of the measuring cable, therefore, the sensor construction is comparable to that of a standard PV module. The electrical connection is realized by a 3m cable.
ALL SENSORS ARE CALIBRATED IN SIMULATED SUNLIGHT AGAINST A REFERENCE CELL OF THE SAME TYPE. THE REFERENCE CELL IS PERIODICALLY CALIBRATED AGAINST A REFERENCE CELL CALIBRATED BY FRAUNHOFER ISE, FREIBURG.
|Solar Cell||Monocrystalline Silicon (52 mm x 52 mm)|
|Current Shunt||High precision shunt resistor directly soldered to the terminals of the cell|
|Operating Temperature||-40°C to +85°C|
|Electrical Connection||3 m LIYYC11Y Cable, UV and weather resistant|
|Power Supply||12 to 30 VDC (30 mA typically at 20 VDC)|
|Interface||RS485 up to 19200 Baud|
|Protocol||The sensor is connected via a 2-wire RS485 bus with open vendorindependent Modbus RTU protocol|
|Galvanic Isolation||1000 V between power supply and RS485 bus|
|Case||Advanced weatherproof junction box made of UV resistant material|
|Dimensions, Weight||140 mm x 108 mm x 42 mm, approx. 300 g|
|Standard and Classification|
|Irradiance||0…1600W/m2, Secondary Standard. Uncertanity ≤ 3% as per IEC67724-7 Class A standard.|
|Drift||Very small drift of <0.3% / year|
|Response Time||1 sec. less than 3 sec. As per IEC67724-7 Class A standard|
|Field of View||171° , Larger than 160° as per IEC67724-7 Class A standard|
|Resolution||.. ≤ 1W/m² as per IEC61724-1 Class A standard|
|Tilt-Azimuthal Angle||0°- 0°,≤ 1° as per IEC67724-1 Class A standard|
|Input#1||3S-AT-78820, Ambient temperature sensor, 2 pin connector|
|Input#2||3S-MT-78820, Module temperature sensor, 3 pin connector|
|Input#3||Wind direction or Relative humidity sensor, 4 pin connector|
|Input#4||3S- WS-PLS, Wind speed sensor, 5 pin connector|
|Output#5||Power and Communication, 6 pin connector|
|Calibration||Individual calibration of each sensors in the natural sunlight at AM 1,5 spectrum by using a compatible calibrated reference cell by Fraunhofer .ISE.|
|Handling Case||5 years Limited warranty against manufacturer defects. Opening of the sensor box by the user or installation staff is not accepted. Opening of the sensor box is one of the reason of terminating the warranty conditions.|
|Baud Rate||1200, 2400, 9600, 19200, 38400|
|Parity||No, even, odd|
|Stop Bit||1, 2 (only at no parity)|
|Factory Default||9600 Baud, 8N1, address: 1|
WIRING EXTERNAL SENSORS
Details of SEVEN Irradiance sensor
The irradiance sensor or PV pyranometer is a photovoltaic sensor used to measure the amount of solar energy in natural light and is particularly used in meteorology. It measures the power of total solar radiation in watts per square meter.
The solar irradiance sensor is a simple and inexpensive solution to monitor the performance of the solar system at any time. Entirely manufactured as a cell for the PV system and equipped with a temperature compensation system, the irradiance sensor measures precisely and reliably the energy supplied and the performance of the system. You will thus be able to benefit from the best performance for your solar panels.
Irradiance sensor with Modbus RTU Connection
In terms of connection or communication with other sensors and dataloggers. Several types of irradiance sensors are available with different output signals such as the irradiance sensor with Modbus RTU connection and the irradiance sensor with analog output. In this text, we will focus on irradiance sensors with Modbus RTU connection.
First of all, Modbus is a serial communication protocol widely used by industrial electronic devices. In Modbus, the connection is established between a master (host) and slaves (devices connected to COM ports). The Modbus allows access to the configuration of the peripherals and to read measurements.
The irradiance sensor with Modbus RTU output is an advanced, weatherproof junction box made of UV-resistant materials. It is constructed from a monocrystalline solar cell connected to a high-precision shunt. It contains a Modbus output which is used to deliver the measurements obtained by the sensor to the datalogger via a RS485 cable. This type of Modbus irradiance sensors also has three input ports that allow the communication with three other sensors such as Wind Speed / direction sensors, Ambient / Module Temperature Sensors, humidity sensor, etc.
Irradiance sensor’s components
An irradiance sensor consists essentially of 3 main parts: Protective box, Photovoltaic cell, Electronic card/board.
The photovoltaic cell, which has a monocrystalline silicon structure, is the part that absorbs solar radiation. It has the same characteristics as a photovoltaic panel cell. Therefore, it behaves in the same way as the panel under the effect of light and heat. Then, with the help of a microprocessor, the electronic card gets the ability to collect the processed data. Because of the additional inputs that SEVEN Irradiance sensor has, the Temperature and Wind speed sensors can be easily connected to the electronic board.
Irradiance sensor examples of use
The Modbus SEVEN irradiance sensor is used for Huawei weather stations; we have obtained Approval from Huawei for our entire weather station which includes the Modbus RTU irradiation sensor, wind speed/direction sensors, and ambient temperature/modules sensors. It is also used for GoodWe stations as it is compatible with its Ezlogger, and with all Modbus dataloggers. You may visit our Website for more information about our sensors and the other type of irradiance sensor, the analog one, which is compatible with too many brands such as Kaco, SMA, SolarEdge, etc.
As SEVEN Sensor Solutions, our engineers are available to provide customers with a remote setup services and information on anything they may need.