Soiling Measurement System for PV Power Plants

The Soiling Measurement System for PV Power Plants allows users to quantify the site-specific effects of soiling on PV module power generation. Applications include:

  • Determining accurate soiling losses for PV performance guarantees
  • Monitoring soiling losses to enable detection of other system-level issues
  • Optimizing washing schedules for best return-on-investment
  • Determining typical soiling rates for forecasting models
  • Collecting pre-construction prospecting data at new sites

The system acts as a soiling sensor by comparing the power output of a naturally-soiled PV reference module to expectations based on a clean PV reference device.


The system includes advanced features ensuring accurate and reliable results not possible with simpler or home-built systems, including:

  • PV Reference Module Hold at Voc or Isc: The measurement unit switches the reference module into the user’s choice of open-circuit (Voc) or short-circuit (Isc) in between measurements, minimizing module degradation due to hot spot formation (crystalline-silicon modules) or ion transport (thin film modules).
  • Power-Based Measurements: Both the short-circuit current and power of reference modules are measured, allowing accurate soiling determination even when soiling is spatially non-uniform.
  • Automatically-Cleaned Reference Device: An optional automatically-washed reference device permits accurate clean irradiance measurements with minimal labor expense by O&M personnel. And the washing system is suited for application in cold climates, so the system does not need to be taken offline in the winter.
  • Measure Snow Losses: An optional heated reference cell allows accurate measurement of irradiance and measurement of power losses due to modules being covered with snow.
  • Capture Exact Soiling Effects: A PV module identical to those used in the user’s PV array is used as the “soiled” reference module. The soiled reference module can be mounted directly on the user’s array mounting structure if desired — even for tracking systems.

The Soiling Measurement System is available in a variety of configurations that support many different customer needs.

Contact us today for more information on the Soiling Measurement System or our other products.


“Measuring Soiling Losses at Utility-Scale PV Power Plants,” by Michael Gostein, J. Riley Caron, and Bodo Littmann. Proceedings of the 40th IEEE Photovoltaic Specialists Conference, 2014, Denver.

“Accurately Measuring PV Soiling Losses With Soiling Station Employing Module Power Measurements,” by Michael Gostein, Tim Duster, and Christopher Thuman. Proceedings of the 42nd IEEE Photovoltaic Specialists Conference, 2015, New Orleans.

“Comparing PV Power Plant Soiling Measurements Extracted from PV Module Irradiance and Power Measurements,” by Michael Gostein, Bodo Littmann, J. Riley Caron, and Lawrence Dunn. Proceedings of the 39th IEEE Photovoltaic Specialists Conference, 2013, Tampa.