Solar PV module soiling sensor 3S-SMS-MB

for photovoltaic applicationsIEC 61724automatic cleaning

Overview
SEVEN Soiling Sensor is designed to measure energy production loss caused by soiling on photovoltaic (PV) panels. It is suitable for commercial, utility, industrial and rooftop PV projects and reports soiling ratio as percentage energy loss (a 10% soiling ratio means ~10% energy loss for the facility).

How the Automatic Soiling Sensor Works

• Two reference cells are installed side by side; one cell is kept clean automatically by a built-in washing system while the other remains exposed like the PV modules.
• Irradiance values from both cells are continuously compared by dedicated software.
• The irradiance 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 for PV Plants
Soiling accumulates dust and particles on PV panels, reducing incident sunlight and energy yield. Typical annual yield reductions by location:

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

Benefits

• Operational visibility — exact production loss available in real time.
• Automatic cleaning — one reference cell is cleaned without manual intervention.
• Low maintenance — minimal annual water consumption (approx. two refills per year for typical tanks).
• Cold-climate option — antifreeze mix available for subzero operation.
• Weather-protected housing — IP54 standard, IP66 optional.
• Direct integration — RS485 Modbus RTU communication with monitoring systems.

Available Models and Key Differences

• 3S-SMS-MB — RS485 Modbus RTU, 100–240 V AC, uncertainty ≤1%, no gateway.
• 3S-SMS-GW — RS485 Modbus RTU, 100–240 V AC, uncertainty ≤1%, gateway option for cloud monitoring.
• 3S-SMS-MB-24V — RS485 Modbus RTU, 24 V DC 5 A, uncertainty ≤1%, no gateway.
• 3S-SMS-GW-24V — RS485 Modbus RTU, 24 V DC 5 A, uncertainty ≤1%, gateway option.

Operation, Maintenance and Data

• Default cleaning: once per day for ~5 seconds (about three hours before solar noon); schedule adjustable up to 3/day.
• Soiling ratio is calculated as a daily average from stable data collected around solar noon; results update after midnight; if insufficient stable data is available, the last valid ratio may be shown.
• Under standard operation the 18 L tank requires refilling about every six months; the 40 L tank about once a year. A typical single run consumes ≈100 ml for 2.5 m hose; tank capacity can cover ~400 days at that rate.
• Recommended installation: mount at same tilt/orientation as PV modules; avoid nearby chimneys, vents or reflectors. Inspect cables, seals and tank regularly and clean tank at each refill. Perform system check at least annually.
• For cold climates use a 65% pure water + 35% antifreeze mix when ambient temperature is below 0°C.
• System stores up to one year of historical data (daily soiling ratios, number of stable data points, water level, sensor on/off logs); data available in GUI or via download.

Standards, Warranty and Delivery

• Complies with IEC 61724-1 (Annex C) for PV soiling measurement.
• Warranty: 2-year covering defects in materials and workmanship.
• Delivery times: small orders ~2–3 weeks; bulk orders (100 pcs) ~8–10 weeks.

Technical specifications

• 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% (IEC61724-1 Class A)
• Data Output: RS485 up to 38400 Baud
• Protocol: Modbus RTU
• Output Rate: 1/s
• Operating Temperature: -20°C … +85°C
• Operating Humidity: 0–100% RH
• Power Supply: 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)
• 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 L or 40 L
• Water Consumption: ≈2 refills per year (standard operation)
• Washing Liquid: 100% pure water above 0°C; 65% pure water + 35% antifreeze below 0°C
• Water Hose Length: 5 m (up to 20 m on request)
• Max Water Line Height: 5 m
• IP Rating: IP54 (IP66 optional)
• Weight: 10.5 kg
• Standard: IEC61724-1 (Annex C)