SILICON IRRADIANCE SENSOR Measurement of Solar Irradiance
Silicon irradiance sensors (Si sensor) show a cost-effective, but rugged and reliable solution for the measurement of solar irradiance, especially for the monitoring of Photovoltaic (PV) systems. Based on the construction of the sensor element corresponding to a PV module they are ideal as refe- rence for the monitoring of PV systems. Especially the spectral response comparable to PV modules as well as the similar inclination error (incident angle modifier) allow an exact analysis of PV energy yields using Si sensor data.
Mode of Operation
A silicon solar cell can be used as an irradiance sensor, because the short-circuit current is proportional to the irradiance. Our sensors are build out of a monocrystal- line Si solar cell connected to a shunt. Due to the low resistance of the shunt the cell operates next to short-circuit.
To minimize influences of tempera- ture to the measuring signal all of our sensors with the extension „TC“ have an active temperature compensation via a temperature sensor laminated to the back surface of the solar cell.
All sensors are calibrated in artifici- al sunlight against a reference cell cali- brated at the Physikalisch-Technische Bundesanstalt (PTB, National Metrology Institute of Germany).
The solar cell is embedded in Ethylen- Vinyl-Acetat (EVA) between glass and Tedlar. The laminated cell is integrated into a case of powder-coated aluminium. Therefore the sensor construction is com- parable to that of a standard PV module. The electrical connection is realized by a 3 m cable or a waterproof (IP67) connector.
Optional Temperature Measurement
Additionally to the irradiance measure- ment our silicon sensors with the extension “-T” are able to measure the temperature of the solar cell using a temperature sensor laminated to the back of the cell. This solar cell temperature can approximately be used as module temperature.
SILICON IRRADIANCE SENSOR Technical Data
Monocrystalline silicon (50 mm x 33 mm) -35°C to 80°C 3 m shielded cable minimal 1 MΩ
• Solar cell:
• Operating temperature:
• Electrical connection:
• Load impedance for Si-V-1.5TC-batt:
• Load impedance for Si-V-1.5TC and -TC-T, Si-V-10TC and -TC-T: min. 10 kΩ • Load impedance for Si-I-420TC and -TC-T: minimal 20 Ω and maximal 400 Ω • Case, protection mode: Powder-coated aluminium, IP 65 • Dimension, weight: 155 mm x 85 mm x 39 mm, approx. 350 to 470 g
• Protocol: M&T (type -MT), MODBUS RTU
• Interface: (type -MB) RS485 up to 38.4 kBaud
• Galvanic isolation: 1.000 V between power supply and bus
The electrical connection of the Si sensor is realized with the inbuilt connector and the suitable plug.
Technical Data of the Plug
• Cable dimensions (best / max.): 0.14 mm2 / 0.25 mm2 (AWG26 / AWG24) • Diameter of cable: 3.5 ... 5 mm
• Protection mode: IP67 in conjunction with the suitable connector
The connection of the different Silicon irradiance sensors are listed in the follo- wing table. The pin numbers are printed at the inside of the plug. Please take care of the mounting of the plugs as shown at the end of this page. Only if these mounting steps are realised the plug meets IP67 when connected.
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