Automatic Reference for Empirical Soiling

Finally, a way to accurately measure the effects of soiling on your array

ARES is a new PV soiling measurement product that measures the effects that soiling has on a PV system.


ARES will provide the following data when installed next to your PV array:

  • Irradiance and Daily Insolation data for clean and soiled panels
  • Daily percent loss due to soiling
  • Soiling rate (the rate at which the panels are soiled and accumulate dust/dirt over time)


Soiling data is the one unknown data set that PV owners and operators seek. Some benefits of ARES are:

  • Maximize solar panel efficiency and predict potential loss due to soiling
  • Aide and support in PV performance guarantees
  • Increased return on investment (ROI) by refining wash schedules.
  • Avoid system-level issues due to soiling like PID and RISO before they occur


Fracsun LLC

San Luis Obispo, CA, USA

Phone: 805-242-3722


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How soiling is measured

The accumulation of dirt on solar panels has drastic, but measurable, effects on the performance of solar arrays. The soiling problem can be addressed by installing Fracsun's ARES device adjacent to the photovoltaic array. ARES measures a brand new metric called the soiling rate. The soiling rate is found by comparing a reference panel that is cleaned daily with another reference panel that is left to naturally collect dirt, dust, or other obstructing matter. The soiling rate is used in a simple algorithm that determines the most economical day to wash the array.



ares products soiling solar analytics dirt dust wash best efficiency fracsun

Easy to install, no power required

The latest ARES model is extremely easy to install next to a new or existing photovoltaic array. Use any of the mounting holes to install on an existing PV rail or rack mount system. Worried about running conduit, DC power, and wiring for an RS-232 communications device? Don't be...ARES is self powered from the sun and will output irradiance and soiling data securely to the cloud via a 3G mobile network. As soon as you turn it on at the site it will begin communicating to your customized web portal on our website.

Product Specifications


  • Integrated 3G cellular module for data output - no wired connection required
  • Dual-cell mono crystalline solar powered - no external power required
  • Irradiance ±10 W/sqm against industry-recognized pyranometer; with temperature compensation
  • Extended temperature Lithium Polymer battery
  • Integrated 12Vdc solenoid output for daily rinse


  • IP-67 rated grey ABS enclosure
  • Six 1/2" perimeter through holes enable a wide range of mounting options to match existing racking on site
  • Angled dual brass nozzles for rinsing system of "clean" panel
  • 1/8" NPT high pressure brass fittings for water connection
  • Solar module level pressure ratings at +/- 2400 Pa for wind and +5400 Pa for​ snow loading

ARES pays for itself

The graphs below show two very indicative case studies using the ARES device. On the left is a site that is considered to have no issue with soiling. The ARES device is still able to improve ROI enough to reduce solar payback by half a year. The study on the right is a rural system typical of a ground mount in an area with farming activities. In this case ARES can reduce the system payback period by over 3 years.

Cumulative Solar Cash Flow Graph
Cumulative Solar Cash Flow Graph