A laboratory-scale solar module cleaning system prototype engineered at MIT eliminates the wasteful use of water to keep solar cells clean. The system uses electrostatic repulsion to cause dust particles to detach and virtually leap off the surface of panels.

Currently, cleaning solar panels is estimated to consume about 10 billion gallons of water per year, aDust particles spread on the bottom metallic electrode are observed to repel on application of voltage between plates separated by 1.5 cm. Source: Sreedath Panat and Kripa K Varanasi/MIT volume that could supply drinking water for up to 2 million people. Dry scrubbing offers a water-free cleaning approach but its abrasive nature gradually takes a toll on solar cell.

The simpler MIT solution uses a transparent electrode to charge dust particles by an applied potential. The electrode consists of a glass plate coated with a 5 nm transparent and conductive layer of aluminum-doped zinc oxide using atomic layer deposition. The non-contact waterless system is operated automatically via an electric motor and is activated by an electrode placed on top of the module surface. The mobile system travels along the panel during cleaning with a linear guide stepper motor mechanism.

The system can be operated at a voltage of around 12 V, and the researchers report in Science Advances that it can recover 95% of the lost power after cleaning for particle sizes greater than around 30 μm.

Such a system could be retrofitted to existing silicon solar cells and could potentially be integrated into the production of future thin-film solar cells during manufacturing. The technology is estimated to save 80% to 90% of cleaning costs, although they will know more after field trials.