Quantification of a Minimum Detectable Soiling Level to Affect Photovoltaic Devices by Natural and Simulated Soils

Abstract

Soil accumulation on photovoltaic (PV) modules presents a challenge to long-term performance prediction and lifetime estimates due to the inherent difficulty in quantifying small changes over an extended period. Low mass loadings of soil are a common occurrence but remain difficult to quantify. In order to more accurately describe the specific effects of sparse soil films on PV systems, we have expanded upon an earlier technique to measure the optical losses due to an artificially applied obscurant film. A synthetic soil analog was sprayed onto glass coupons at very brief intervals with a high-volume, low-pressure pneumatic sprayer. Light transmission through the grime film was evaluated using a quantum efficiency test stand and UV/vis spectroscopy. A 0.1-g/m 2 grime loading was determined to be the limit of mass measurement sensitivity, which is similar to some reports of daily soil accumulation. Predictable, linear decreases in transmission were observed for samples with a mass loading between 0.1 and 0.5 g/m 2 . A similar change was observed for soiled coupons from an outdoor monitoring station. Collected soil from the field coupons was analyzed to develop a compositional analog for indoor studies. Natural and synthetic soils produced similar decreases in transmission.

Modelling photovoltaic soiling losses through optical characterization

“…Glass coupons are a standard method for the analysis of soiling of photovoltaics and have been used in a number of research papers 11,39,41,42,[47][48][49][50][51] . In addition, recently launched low-maintenance soiling detectors quantify the loss of PV modules through the optical analysis of the contamination accumulated on glass 52,53 .…”

Correlating photovoltaic soiling losses to waveband and single-value transmittance measurements

“…The use of glass coupons to analyze and monitor the soiling of PV modules is a standard method for the soiling community, already employed for both research and commercial purposes. Outdoor mounted PV coupons were used by Burton et al [21] to study the composition and the size distribution of soiling deposited on PV modules. The same setup, replicated also in a second location, was used by Boyle et al [22] to investigate the deposition of particle matter on PV systems.…”

Monitoring photovoltaic soiling: assessment, challenges, and perspectives of current and potential strategies

“…However, glass coupons have been extensively used in the literature for PV soiling studies. Burton et al (Burton et al, 2015) used field coupons to assess the optical effects and the mass distribution of soiling. Using a similar setup on a different location, Boyle et al (Boyle et al, 2016) examined the airborne particles' deposition and mass accumulation on glass samples.…”

“…Burton et al. ( Burton et al., 2015 ) used field coupons to assess the optical effects and the mass distribution of soiling. Using a similar setup on a different location, Boyle et al.…”

“…The first important factor affecting the deposition processes is the concentration of suspended particles in the atmosphere. As shown in Table 4 , researchers have reported correlations between mass accumulation and soiling or transmittance losses, using different sets of data ( Boyle et al, 2013 , 2015 ; Burton et al., 2015 ; Elminir et al., 2006 ; Hegazy, 2001 ; Jiang et al., 2011 ; Kaldellis and Kapsali, 2011 ). A comparison of these models is not currently possible, as these were developed for different conditions and glass surface designs and configurations.…”