Class A pyranometer 3S-IS

RS-485serialModbus RTU

Overview
The 3S-IS irradiance sensor provides temperature‑compensated irradiance measurements for PV plants and transmits data via Modbus RTU over RS485. Supplied with mounting bracket and 3 m UV‑resistant LIYYC11Y cable, the aluminium UV‑protected housing is available in IP54 (standard) with IP65/IP68 options for harsher environments. Designed for plug‑and‑play integration with PLC, SCADA and data loggers.

How the 3S-IS Sensor Works

• A monocrystalline reference cell generates a short‑circuit current proportional to incident irradiance.
• A precision shunt resistor converts the current into a measurable voltage signal.
• A PT1000 temperature sensor mounted at the back of the cell compensates for thermal effects.
• An electronic board processes signals and calculates temperature‑compensated irradiance values in W/m².
• Data are transmitted to receivers via RS485 using the Modbus RTU protocol.

Why Choose the 3S-IS Irradiance Sensor?

• Measurement class: IEC 61724-1 Class A compliance with uncertainty ≤1%, calibrated per IEC 60904-2.
• Fast response: Standard 1 s response time (optionally 500 ms on request) for near real‑time monitoring.
• Field‑ready: UV‑protected aluminium housing with IP54 standard (IP65/IP68 options) and operating range −40 °C to +85 °C.
• Easy integration: Plug‑and‑run design; Modbus RTU over RS485 for direct connection to PLC, SCADA and data loggers.
• Expandable: Model options allow connection of external sensors (ambient/module temperature, wind, humidity, wind direction) to act as a monitoring hub.

Technical specifications
Item Code: 3S-IS, 3S-IS-1, 3S-IS-2, 3S-IS-2T, 3S-IS-3, 3S-IS-4, 3S-IS-5
Reference Cell: Monocrystalline silicon (31 mm × 31 mm)
Irradiance Range: 0–1600 W/m²
Uncertainty: ≤1% (IEC 61724-1 Class A)
Resolution: 0.1 W/m²
Response Time: 1 s (500 ms optional)
Drift: <0.3% / year
Field of View: >160°
Tilt‑Azimuth Angle: 0°–0°, ≤1°
Output Rate: 1 Hz
Data Output: RS485 up to 38400 Baud
Protocol: Modbus RTU
Power Supply: 12–30 V DC
Power Consumption: 30 mA max @24 VDC
Cable: 3 m LIYYC11Y PUR, UV and weather resistant
Galvanic Isolation: 1000 V between power and RS485 bus
Cell Temp. Sensor: PT1000 Class A (EN 60751)
Operating Temp.: −40 °C to +85 °C
Operating Humidity: 0–100%
Dimensions: 140 × 110 × 42 mm (W × L × H)
Weight: 0.3 kg
IP Rating: IP54 (IP65, IP68 options)
Housing: Aluminium
Standards: IEC 61724-1:2021, IEC 60904 series
Calibration: Each unit calibrated on Class AAA sun simulator per IEC 60904-2 / IEC 60904-4 using reference cell calibrated by ISFH; outdoor verification vs Fraunhofer ISE reference cell.

Available models (summary)
3S-IS / RS485 Modbus RTU / ≤1% / No external sensor inputs
3S-IS-1 / RS485 Modbus RTU / ≤1% / Ambient OR Module Temperature sensor
3S-IS-2 / RS485 Modbus RTU / ≤1% / Ambient OR Module Temperature; Wind Speed sensor
3S-IS-2T / RS485 Modbus RTU / ≤1% / Ambient AND Module Temperature sensors
3S-IS-3 / RS485 Modbus RTU / ≤1% / Ambient, Module Temperature and Wind Speed
3S-IS-4 / RS485 Modbus RTU / ≤1% / Ambient, Module, Wind Speed; Wind Direction OR Relative Humidity
3S-IS-5 / RS485 Modbus RTU / ≤1% / Module Temp, Wind Speed, Wind Direction, Relative Humidity and Ambient Temp

Modbus specification

• Baud rates: 1200, 2400, 9600, 19200, 38400
• Parity: None, Even, Odd
• Stop bits: 1 or 2 (2 only if Parity = None)
• Default configuration: 9600, 8N1, address 1

Calibration and tests
Each sensor is calibrated on a Class AAA solar simulator according to IEC 60904-2 and IEC 60904-4 using an ISFH‑calibrated reference cell. Units are additionally verified outdoors against a Fraunhofer ISE calibrated reference cell.

Applications
Performance monitoring and energy yield assessment of PV plants, integration with PLC/SCADA and data loggers, meteorological stations and PV test sites.

Components

• UV‑resistant aluminium sensor housing
• Laminated monocrystalline PV reference cell (EVA/Tedlar)
• Electronic board with microcontroller for signal conditioning and Modbus RTU communication