Modbus RTU solar radiation sensor 3S-IS-LR

serialModbuswith serial interface

Overview The 3S-IS-LR irradiance sensor measures solar irradiance for residential, rooftop and small-scale PV systems. Data are output via an RS-485 serial interface using the Modbus RTU protocol for integration with inverters, data loggers and SCADA.

Measured parameters

• POA irradiance (W/m²): plane-of-array irradiance used for Performance Ratio (PR) and yield analysis.
• Module temperature: back-of-module temperature (available on models with external module sensor input).
• Ambient temperature: air temperature near the PV plant (available on models with external ambient sensor input).
• Wind speed: horizontal wind speed (available on models with external wind sensor).

Model options (differences are number/type of external sensors)

• 3S-IS-LR – RS485 Modbus RTU – no external sensor input
• 3S-IS-LR-1 – RS485 Modbus RTU – Ambient OR Module Temperature sensor input
• 3S-IS-LR-2 – RS485 Modbus RTU – Ambient OR Module Temperature; Wind Speed sensor
• 3S-IS-LR-2T – RS485 Modbus RTU – Ambient AND Module Temperature sensors
• 3S-IS-LR-3 – RS485 Modbus RTU – Ambient, Module Temperature and Wind Speed sensors

Key advantages

• Cost-effective for wide deployment in residential and small commercial PV installations.
• SunSpec-compliant and Modbus RTU for straightforward system integration.
• IP67 enclosure and UV-resistant cable suited to outdoor PV environments.
• Galvanic isolation, low long-term drift and ongoing software support; 5-year warranty.

Installation and maintenance

• Mount for POA: install sensor coplanar with modules (same tilt and azimuth) to measure true plane-of-array irradiance.
• Avoid shading and reflections: keep the sensor clear of rails, conduit and objects that may cast shadows or reflect light onto the cell.
• Wiring: connect power and RS485 data lines to the designated ports; device begins reporting automatically once powered.
• Maintenance: periodically wipe the sensing surface to remove dust and residues to prevent under-reading.

Why choose this product Designed for residential and small commercial PV monitoring where ≤3% uncertainty is appropriate; delivers right-sized accuracy and connectivity at an accessible price point.

Technical specifications

• Item Code: 3S-IS-LR
• Reference cell: Monocrystalline silicon (31 mm x 31 mm)
• Irradiance range: 0 – 1600 W/m²
• Uncertainty: ≤3%
• Resolution: 0.1 W/m²
• Drift: <0.3% / year
• Output rate: 1/s
• Data output: RS485 up to 38400 Baud
• Communication protocol: Modbus RTU
• Power supply: 12–30 V DC
• Power consumption: 10 mA max @ 24 VDC
• Electrical connection: 1 m LIYYC11Y PUR cable, UV and weather resistant (included)
• Galvanic isolation: 1000 V between power supply and RS485 bus
• Enclosure dimensions: 118 mm x 84 mm x 55 mm (WxLxH)
• Weight: 300 g
• Ingress protection: IP67
• Sensor housing material: ABS
• Standards: IEC 61724-1:2021 and IEC 60904