Solar panels are a black hole of water. Electrostatic repulsion wants to solve it

Spread the love

The objective is clear. In its commitment to renewables, Brussels wants to double the capacity of solar energy installed in the EU to reach 300 GW in 2028 . She is not alone in the effort. In China and the US , among other countries, they have also moved to give more weight to photovoltaics and the sector itself has been innovating for years to achieve more efficient installations and gain new spaces .

The point is that more solar panels also imply a higher maintenance requirement . And that, in turn, has its own consequences, such as a high demand for water. After all, the most common method for cleaning hobs is pressure jets and sprays.

In 2022, researchers from the Massachusetts Institute of Technology (MIT) collected the available studies, used the calculator and concluded that both photovoltaic plants and concentrated solar thermal energy (CSP) plants consume more or less each year during their cleaning tasks. , between 3.7 and 18.9 million liters of water per 100 MW.

A lot of water… and a considerable expense

That translates into a lot, a lot of water, when taken to a global scale.

At the time of the study, with global photovoltaic capacity exceeding 500 gigawatts (GW), it translated into annual consumption across the planet of up to 10 billion gallons of water, the equivalent of 37.8 billion liters . We are talking about a sufficient contribution to cover the annual needs of up to two million people in developing countries.

The alternative uses that could be given to such a supply – a similar approach can be done with other uses of water, from washing streets to watering gardens – is not, however, the only data that encourages reflection. Sprinklers and washers also cost money, especially in desert regions where the liquid must be transported. It is estimated that cleaning with water can account for up to 10% of the maintenance cost of a photovoltaic park.

With this data on the table, the question is obvious: Are there other ways to clean solar panels? The option of relaxing maintenance is not on the table. It is estimated that the accumulation of dust on the plates and mirrors can reduce their productivity by about 30% per month .

At MIT there is a team convinced that there is an alternative that would allow us to save enormous amounts of water. Which? Electrostatic repulsion, a method that dispenses with liquid, brushes or other mechanisms that could scratch the delicate surface of the panels.

The system consists of passing an electrode—it comes with a simple metal bar—over the plate to generate an electric field that imparts a charge to the dust particles while another is applied through a very thin conductive layer on the surface of the panel. The result is that the dirt fragments “jump off” , they are repelled… and the panels end up clean.

For the system to work, ambient humidity plays a key role.

“We carry out experiments with variable humidity, from 5% to 95%. As long as it is higher than 30% , almost all particles from the surface can be eliminated, but as it decreases it becomes more difficult,” says Sreedath Pana t, an MIT student who has discussed his work with engineering professor Kripa Varanasi in a article published in Science Advance .

The percentage may seem excessive, especially if the system is proposed for photovoltaic installations in the desert, where water is scarcer and cleaning with sprinklers is higher, but the team insists that even in the majority of these environments it could apply its solution.

“It works when 30% humidity is reached and most deserts enter that regime.” It would be a matter, they explain , of scheduling the tasks well to take advantage of the dew.

You might also like