Systematic review of soiling mitigation strategies for solar photovoltaic panels

One of the most important factors impairing the performance and dependability of solar photovoltaic (PV) systems is soiling, which can result in efficiency losses of about 6–7% in a matter of months and more than 20–30% over extended exposure; reductions of up to 34% have been reported at dust loads of about 10 g/m². In arid, humid, and urban settings, this systematic review examines soiling mechanisms and assesses mitigation strategies, emphasizing their performance recovery and technology readiness levels (TRLs). While manual and automated water-based cleaning restores 90–95% of power output and is commercially mature (TRL 9), it is constrained by water consumption and quality issues. Natural cleaning by rainfall can remove 70–90% of loosely deposited dust (TRL 9). Large-scale arid deployments can benefit from robotic dry-cleaning systems, which are fully commercialized (TRL 9) and achieve 90–99% dust removal with little to no water use. Under laboratory conditions, electrostatic and electrodynamic dust removal methods show up to approximately 95% recovery; however, they are still in the experimental stages (TRL 3–4), with difficulties in high humidity. Vibrational and ultrasonic cleaning techniques are in the early stages of development and offer about 60–70% efficacy (TRL 2–3). Hydrophobic, hydrophilic, and photocatalytic surfaces are examples of passive anti-soiling coatings that decrease dust adhesion and produce modest efficiency gains of 5–15% (TRL 4–6), but they have problems with long-term stability and durability. The review suggests next-generation multifunctional smart coatings that combine thermochromic cooling capabilities with superhydrophobic self-cleaning behaviour, backed by rainwater-harvesting recirculation systems for water-stressed areas. Overall, the results highlight the need for region-specific, cost-optimized hybrid strategies in order to maximize PV energy yield and ensure the long-term sustainability.