Dynamics of particles on solar panels farms under turbulent environmental conditions

PhD / Long term visitor's project

Solar power is rising in prevalence, and open deserts are ideal locations for solar farms worldwide, but excessive heat and wind-propelled debris reduce efficiency in power output and induce degradation in their expected life.

Increased velocity and mixing promote capture of material from desert floors causing higher rates of deposition and fatigue-inducing impact even in mild conditions. Dust particles ranging from 0.4 µm on a normal day and up to 1.2 µm in storm conditions can accumulate on panels in open environments. This results in important losses in power generation efficiency, reaching up to 35%. Dust accumulation is inevitable in dessert areas and most solar farms require regular panel maintenance and cleaning to remain effective, demanding extensive human labor and important water resources. Also, significantly larger particles can interact with the panels, such as rain droplets, pollen or pollutants. This means that both tracer particles (i.e. particles that follow the streamlines) and inertial particles (particles whose dynamics deviates from the streamlines due to finite size or density effects) play an important role on the efficiency of these systems.

We propose here an experimental study on the coupling of solar farms, turbulent flows, and particles. Our ambition is to:

• Construct realistic experiments in wind tunnels, that include a scaled model of one (or several) solar panels. Experiments will use active grids that allow to generate bespoke turbulent flows, close to the ones found on applications. Furthermore, both inertial particles (water droplets) and tracers (dust) will be injected to the flow.

• Characterise the carrier flow and the particles dynamics using optical techniques.

• Measure, for different turbulent flows, the dynamics and deposition of particles for different array configurations and tilt angles, aiming at finding the parameters that minimize particle deposition.

• Define rules of thumb which will provide solar farm designers with advanced tools to reduce such unwanted effects.

The expected breakthrough of this work is to find, for given turbulent conditions, the configuration of a solar farm that minimises dust deposition. This includes strategies which pursue advantageous positioning of the panels as well as their angle and orientation.