Automatic Reference for Empirical Soiling

Period of Performance: 06/12/2017 - 03/11/2018


Phase 1 SBIR

Recipient Firm

Fracsun LLC
16850 Walnut Avenue Array
Atascadero, CA 93422
Firm POC, Principal Investigator


The accumulation of dirt on solar panels, also referred to as soiling, is the greatest avoidable performance loss in photovoltaic systems. Soiling comes from many anthropogenic and natural sources making it difficult to develop a standard model for accumulation across all photovoltaic systems operating today. The industry is in need of a cost effective device that will allow this key metric to be managed in a way that optimizes performance for the life of the system. The soiling problem can be addressed by installing a device adjacent to the photovoltaic array that measures a new metric called the soiling rate. The soiling rate is found by comparing a reference cell that is cleaned daily with another reference cell 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. Prototypes of this device have been installed at sites and have proven to optimize array performance when the array is washed at the calculated wash date, or in some cases, when a wash is not needed. During Phase 1 of this project, the soiling measurement device will move from the final development stages to small-scale production. The mechanical portion of the design will be finalized for form, fit, and function. The electronic portion of the design, tested for appropriate functionality and reliability in outdoor conditions. Suppliers for each component in the design will be selected based off the samples received. Small quantity manufacturing builds of the device on a small-scale will be occurring during the end of Phase 1. Future commercial applications of generating this data are plentiful. Upon completion of Phase II development will be concluded on a soiling database that serves to complement existing solar resource databases (TMY, NSRDB, SolarGIS, Meteonorm, etc.). This will aid the entire solar community in providing daily average soiling rates for locations all over the country and globe. This data will help financiers fine-tune cash flow analysis of potential projects, support project developers by improving production estimates for potential customers and more. Phase III of this work will seek to develop a platform that enables automatic cleaning crew dispatch. This will be driven through channel partners acting as regional operators all over the country and following scheduling instruction that is driven by local measurements on site. Using this method, soiling loss performance guarantees can be implemented into Energy Output Guarantees to ensure photovoltaic plants under this program are operated and maintained at their maximum available performance.