April 15, 2019
A lot of solar farms add motors to their solar panels so they can track the sun as it moves through the sky. These panels will capture 10 to 30 percent more energy than their stationary cousins. However, solar trackers are also susceptible to damage brought on by high power winds.
Even when solar panels are stowed in a horizonal position, at a certain wind speed they begin to oscillate 20 degrees above and below their intended position.
A solar panel in a single-axis solar tracking configuration.
NEXTracker, and several other solar tracking companies, hired CPP Wind Engineering (CPP) to simulate how wind affects solar panels and how to prevent damage from happening.
With the use of Ansys Fluent and a series of wind tunnel tests, CPP was able to pinpoint that the failure can be attributed to wind vortexes. CPP then determined a series of operating conditions and design alterations to prevent the oscillations that damage the solar tracker.
Since CPP was simulating a new phenomenon, any simulation they built needed validation.
Though the wind tunnels were unable to reveal the mechanism behind the oscillations, they were able to recreate them. Thus, CPP could use the wind tunnel data to calibrate and validate its simulations.
Once the simulations were validated, CPP determined that vortexes were the root cause of the solar panel oscillations.
Simulation of the air around a rotating solar panel.
CPP determined that a vortex would form above the leading edge of the panel at high winds. This vortex caused a moment which twisted the solar tracker up. Once the vortex separated, the moment dropped to zero and the panel fell below the stow position.
A second vortex would then form on the underside of the panel pulling it down. Once this vortex separated, the panel snapped back up. This cycle would continue until the oscillations damaged the panel.
Now that CPP understood the root cause of the oscillations it was able to devise protocols and design changes that fixed the problem.
For more on how to increase the service life on solar panels, read: Preserving the Life of Solar Power Inverters.