Introduction
Engineers and physicists use models of reality to gain insight into physical phenomena that are not directly accessible for us human beings. This approch goes back e.g. to Johannes Kepler, who predicted the movement of planets by evaluating mathematical formulas he created. Like Kepler, engineers use models to predict events that did not yet happen (predict the future) or to make phenomena visible for which we human beings have no sensors – like invisible fluid flow.
Unfortunately, reality is very complicated. So those mathematical models are always only a simplified representation of reality. Depending on the complexity of the model, knowledge of the actual circumstances and the experience level of the engineer, the model results deviate more or less from what happens in reality.
Three Approaches vs. Reality
For evaluating wind flow and resulting loads on complex shaped objects like buildings with panels thereon, there are different computational approaches possible, each of which has advantages and disadvantages.
- Reality: Reality is ground truth. In the case of wind loads on solar panels, these are the actual wind loads that your solar panels are subjected to for real. These loads are unknown and you would like to predict them.
- 3D computer fluid dynamics (CFD) simulation: This is the best, engineers can do nowadays to evaluate fluid dynamics situations with computational means. However, already their results deviate from reality. Depending on the complexity of the problem, these simulations can take weeks or even months to set up and a significant amount of time to get solved on a supercomputer. Even in easy cases, such simulations cost thousands of dollars, up to hundred thousands for high end projects. Nevertheless we can offer you such a service for standard cases. Please contact us.
- 2D computer fluid dynamics (CFD) simulation: This is a simplified version of a 3D model, in which only a 2D slice of the situation is modelled. This is what you get here on solarcfd.com. Of course, as our world is 3D, this leads to a higher deviation from reality. One effect is that the air flow is not able to pass laterally by the panels or building leading to generally higher wind loads on the panel. Moreover, in reality, wind can come from 360° around the building. On solarcfd.com only two wind directions are possible.
- National and International Standards: These are calculation recipies based on many studies, experiments and many years of experience. They have usability and safety in mind. However the approaches used are often a severe generalization of reality, which is compensated by adding high safety margins to the results.
Conclusion: As it is unknown how far the wind loads estimated by solarcfd.com deviate from reality and how they are representative for worst case situations, you must not use them to design or evaluate any safety relevant part of a solar system.
