Inside Ames: Why rain and solar panels don’t get along

PCWorld | Aug 14, 2015

Researchers at Carnegie Mellon University are investigating what causes solar panels to lose efficiency and what can be done to improve their performance.

The sun is always shining here in California, which means there’s lots of solar panels. Researchers at Carnegie Mellon say there’s one simple thing you can do to improve their performance.
Buying and installing solar panels is a big investment. When you decide to go solar, you want those panels to be efficient and save you as much money as possible over their 10 to 20 year lifespan.

Abraham Ishihara
Senior Scientist, Carnegie Mellon University
The solar array industry has come a long way. However, we are still just understanding the long-term performance characteristics of solar panels.

This is where Ishihara’s research at Carnegie Mellon University comes in. He’s studying how solar panels age, what causes their performance to degrade and how that can be improved.
On a second floor rooftop at NASA’s Ames Research Center in Silicon Valley, an array of solar panels with over one thousand sensors is sending detailed information on their electricity generation and temperature throughout the day.
That data is being collected and used to build online models, like this one.

Red means there is mismatch between the cells, arise due to manufacturing imperfections, arise if you don’t clean your panels, leaves, bird droppings.

For highest efficiency, all these cells should be green
Another model measures the cell temperatures to see where and why hotspots are created. A hotspot can reach over 100 degrees Celsius, or 212 degrees Fahrenheit. If this happens day after day, it can lead to permanent damage.
Ishihara has been collecting data on how solar panels perform under different conditions for five years. He wants to develop a model for performance and degradation that can be applied to other solar panel systems.
The research is ongoing, but he’s already discovered that rain isn’t necessarily helping keep the panels clean

when there’s a rain, dust can accumulate in the corners of your array and that can lead to significant heating, left unchecked that can cause performance degradation.

So there you have it. If you want to make the most out of your solar panel investment, you gotta keep them clean.