Sandia National Laboratories engineers have been studying the most effective ways to use solar photovoltaic (PV) arrays—a clean, affordable, and renewable way to keep the power on. Systems are relatively easy to install and have relatively small maintenance costs. They begin working immediately and can run unassisted for decades.

But clouds could dim industry growth: What happens when they cover part of a solar PV array and cause a dip in output? How big is the dip, and how can a utility company compensate for it?

Sandia researcher Matt Lave has been working to understand that drawback and determine just how much clouds can affect solar power plant output. Typically, sunlight is measured using a single irradiance point sensor, which correlates nicely to a single PV panel. But that doesn’t translate to a large PV power plant. “If a cloud passes over, it might cover one panel, but other panels aren’t affected,” Lave said. “So if you use the single point sensor to represent the variability of the whole power plant, you will significantly overestimate the variability.”

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