Table 3 Advantages and disadvantages of soiling mitigation methods

Manual labor cleaning

Efficient in cleaning the PV panel

1) Cleaning costs are high [130].

2) Severe damage or cracks resulting from contacting the surface of the PV panel directly, which could be minimized using certain rubber foam and brushes [131]

Natural cleaning

Free of charge (rainfalls)

1) Depends on the site condition and the weather

2) Large dust particles more than 10 μm can be removed easier than the smaller ones (2–10 μm) [132].

Water cleaning

1) Decreasing system temperature [133,134,135,136,137,138]

2) Helps in reducing the reliability on rainfalls (natural cleaning)

1) Requires a permanent supply system [138]

2) Splashing and evaporation, resulting in water loss [139]

3) Not suitable in dry regions

4) Requires power for concentration of chemicals, refilling of the tank and using pumps that reduce the system output [139]

5) High water consumption costs, in addition to labor cost for manual system

6) Possibility of accumulating dirt if the panel is wet due to the dew phenomenon

7) Presence of thermal shocks [140]

Mechanical cleaning

1) Helps in decreasing the temperature of the system without using water as a cleaning technique

2) The cleaning system is activated using automatic brushes, wipers, etc. by applying different sensors and controllers such as (PLC, microcontrollers) [106, 141].

3) Reduces labor cost due to system independency [107]

4) Fast response, high stability, and reliability

1) Accumulation of dirt on the cleaning system

2) Requires maintenance

3) High initial cost and power consumption

4) Abrasive damage resulting from direct contact with PV panels’ surface

EDS

1) Very fast cleaning action [115]

2) Low power consumption [142]

3) High flexible method

1) Degradation on the plastic screen resulting from uncertain durability consideration on ultraviolet [116]

2) The solar panels’ output power is decreased by 15% [115, 116].

3) Requires a dry ambient condition; unreliable in wet conditions or cemented dust [110, 115, 116]

4) Less effective for fine dust particles between 0 and 5 μm [112]

5) High initial cost

Super hydrophobic surface

There is no need for an external source of power.

1) Accumulation of dirt on the PV surface due to the high surface energy of the polymer layers and the plastic screen may degrade due to high UV exposure [116, 120, 143].

2) Layer deterioration due to the effect of chemicals found in salty air and acidic rains [126]

3) The site surrounding circumstances might be responsible in accumulating more dirt on the PV surface for a long time [144] and whenever the coating is deteriorating [116, 143].

4) It takes less time to decay compared with hydrophilic coatings.

5) Depends on rainfall

6) High initial costs in case of large-scale PV systems

Super hydrophilic surface

1) Does not require external power source

2) Decomposing the organic dust using the photocatalytic effect [128, 145,146,147]

3) Low adhesion to dirt particles [148]

4) Showing better performance recently than super hydrophobic surface [149]

1) Accumulation of more dirt, whenever the coating is decayed

2) Depends on rainfall

3) The initial costs are high in case of large-scale PV systems.

Antistatic coating with mechanical vibrator [98]

1) Effective in harsh environments

2) Not water dependent

1) Extra cost; the initial cost of the mechanical vibrator is around 10% of the PV panel cost.

2) Requires maintenance every 6 months

3) Noisy