Solar PV module soiling sensor 3S-SMS-MB

for photovoltaic applicationsautomatic cleaningIEC 61724

Product overview
SEVEN Soiling Sensor is designed to measure the loss of energy production due to soiling caused by environmental factors on photovoltaic panels. The sensor is suitable for commercial, utility, industrial and rooftop projects and notifies the user of production losses due to soiling. A soiling ratio of 10% means there is 10% energy loss in the facility.

How the Automatic Soiling Sensor works

• Two reference cells are installed side by side.
• One cell is automatically kept clean by a built-in washing system while the other cell is left exposed to dust and dirt like the PV modules.
• Irradiance values from both sensors are continuously compared using specialized software.
• The difference is reported as a soiling ratio (%) indicating power loss.
• Data is transmitted via RS485 (Modbus RTU) to SCADA, PLC, or datalogger systems for integration.

Why soiling monitoring matters
Soiling accumulates dust and particles on PV panels, blocking sunlight and reducing energy production. Impact examples include:

• 2–5% annual yield loss in moderate climates.
• 10–15% or more in deserts and industrial zones.

Benefits

• Financial clarity: know exact production loss in real time.
• Automatic cleaning system: keeps one reference cell clean without manual work.
• Low maintenance: uses minimal water annually (approx. two refills per year for typical tanks).
• Climate ready: antifreeze option for cold climates.
• Durable and reliable: weather-protected housing (IP54 standard, IP65 optional).
• Seamless integration with Modbus RTU-based monitoring systems.

Available models and differences
The 3S-SMS series is offered in MB and GW variants, and in 100-240 V AC or 24 V DC power supply versions. MB models connect directly to Modbus-compatible systems; GW models include a gateway for cloud monitoring.

Technical specifications (table)
Item Code: 3S-SMS-MB, 3S-SMS-GW, 3S-SMS-MB-24V, 3S-SMS-GW-24V
Soiling Ratio: 0% – 100%
Resolution: 0.1
Uncertainty: ≤1%
Data Output: RS485 up to 38400 Baud
Communication Protocol: Modbus RTU
Output Rate: 1/s
Operating Temperature Range: -20°C … +85°C
Operating Humidity Range: 0 to 100% RH
Power Supply: 110-240V AC or 24V 5A DC
Power Consumption: 20 mA @ 24 V DC when the pump is passive; 3 A @ 24 V DC when the pump is active
Electrical Connection: 3 m LI2Y(st)C11Y PUR Cable (UV and weather-resistant)
Galvanic Isolation: 1000 V between power supply and RS485 Bus
Water Tank Capacity: 18 Liters or 40 Liters
Water Consumption: ~2 times filling per year
Washing Liquid: 100% pure water above 0°C; 65% pure water + 35% antifreeze below 0°C
Water Hose Length: 5 m (on request up to 20 m)
Max. Water Line Height: 5 m
IP Rating: IP54 (Optional IP65)
Weight: 10.5 kg
Followed Standard: IEC61724-1 (Annex C)

Operation and maintenance notes

• Default cleaning: once per day for 5 seconds about three hours before solar noon; cleaning frequency adjustable (up to 3/day).
• System stores up to one year of historical data (daily soiling ratios, number of stable data points, water level status, sensor on/off records).
• Install at same tilt/orientation as PV modules and avoid nearby chimneys, vents or reflective surfaces.
• Inspect cables, seals and water tank regularly; clean tank at each refill; perform system check at least once a year.
• For cold climates use 65% water + 35% antifreeze when ambient temperature is below 0°C.

Features / technical specifications

• Item Code: 3S-SMS-MB, 3S-SMS-GW, 3S-SMS-MB-24V, 3S-SMS-GW-24V
• Soiling Ratio range: 0% – 100%
• Resolution: 0.1
• Uncertainty: ≤1% (IEC61724-1 Class A)
• Communication: RS485 (Modbus RTU), data output up to 38400 Baud
• Output Rate: 1 measurement per second
• Operating temperature: -20°C to +85°C
• Operating humidity: 0–100% RH
• Power supply options: 100-240 V AC or 24 V DC (5 A)
• Power consumption: 20 mA @24 V DC (pump passive), 3 A @24 V DC (pump active)
• Water tank capacity: 18 L or 40 L
• Water consumption: approx. two fillings per year (typical)
• IP rating: IP54 standard, IP65 optional
• Weight: 10.5 kg
• Standards: IEC61724-1 (Annex C)