Ashes to Ashes, Dust to Dust: Averting a Potential Showstopper for Solar Photovoltaics

Soiling, especially the sedimentation of dust particles on the exposed surfaces of solar collectors, is critical to the operation of solar systems-even possibly a 'showstopper' in many regions of the world. Historically, this important issue has received intermittent research attention over the past 7-decades, with studies mainly focused on the relationship of dust accumulation to performance. Significantly fewer studies relate to the mitigation using coatings and other physical mechanisms. Cleaning methods have also been limited in scope, primarily using solutions or techniques that are water-based. Recently, interest has been increasing with the growing markets and adoption of solar technologies in the MENA (Middle East and North Africa) and desert regions, where sand particles (1-μm to 500-μm) are problems. This becomes serious when combined with dew or other moisture forming cementitious coatings that can be difficult to remove. This paper provides a comprehensive review of past and recent research work on the impact of dust on solar-PV performance with a focus on issues relating to MENA/desert regions. This paper also reports on progress with dust mitigation approaches. We report our contributions in the microscopic and chemical composition analyses of the 'dust samples' from various MENA and India - showing differences in composition, morphology that can affect accumulation and resulting performance. The focus is on PV (glass) surfaces. Alternative methods (mechanical, electrostatic, liquid, vibrational) for cleaning these surfaces are also examined. Some future research directions & technology requirements are cited.