Green Blog
A better web. Better for the environment.
Should you spring clean your solar panels?
7/31/09
Ever since we
assembled a 1.6 MW solar panel installation
at our
headquarters
in Mountain View in 2007, we've been wondering, "Does cleaning the solar panels make them more effective?" We thought it might, but we needed to be sure. So we analyzed the mountains of data that we collect about the energy that these panels produce — after rain, after cleaning and at different times of the year.
We have two different sets of solar panels on our campus — completely flat ones installed on carports, and
rooftop ones
that are tilted.
Since the carport solar panels have no tilt, rain doesn't do a good job of rinsing off the dirt they collect. (Also, our carports are situated across from a sand field, which doesn't help the situation.) We cleaned these panels for the first time after they had been in operation for 15 months, and their energy output doubled overnight. When we cleaned them again eight months later, their output instantly increased by 36 percent. In fact, we found that cleaning these panels is the #1 way to maximize the energy they produce. As a result, we've added the carport solar panels to our spring cleaning checklist.
The rooftop solar panels are a different story. Our data indicates that rain does a sufficient job of cleaning the tilted solar panels. Some dirt does accumulate in the corners, but the resulting reduction in energy output is fairly small — and cleaning tilted panels does not significantly increase their energy production. So for now, we'll let Mother Nature take care of cleaning our rooftop panels.
Accumulated dirt in the corners of a rooftop solar panel
We've also been crunching numbers on dollars-and-cents; the more energy our panels produce, the sooner we'll be paid back by our solar investment. Our analysis now predicts that Google's system will pay for itself in about six and a half years, which is even better than we initially expected.
If you want to learn more about our solar study, check out these
slides
showing the effects that seasonality, tilt, dirt, particulate matter, rain and cleaning have on Google's solar energy output. We hope you solar panel owners out there can tailor our analysis to the specifics of your own installation to produce some extra energy of your own!
Posted by Winnie Lam, Senior Product Manager
Archive
2016
Sep
Aug
Jul
Jun
Apr
Feb
2015
Dec
Nov
Oct
Sep
Aug
Jul
Feb
2014
Dec
Nov
Sep
Aug
Jul
Jun
May
Apr
Jan
2013
Nov
Oct
Sep
Aug
Jul
Jun
May
Apr
Mar
Jan
2012
Dec
Nov
Oct
Sep
Jul
Jun
May
Apr
Mar
Jan
2011
Dec
Oct
Sep
Aug
Jul
Jun
May
Apr
Mar
Feb
Jan
2010
Dec
Nov
Oct
Aug
Jul
May
Apr
Mar
Feb
Jan
2009
Dec
Nov
Oct
Aug
Jul
Jun
May
Apr
Mar
Feb
Jan
2008
Dec
Nov
Oct
Sep
Aug
Jul
Jun
May
Apr
Mar
Jan
2007
Dec
Nov
Oct
Sep
Aug
Jun
2006
Nov
Oct
Feed
Google
on
Follow @google
Follow
More Google Green
Google Green site
Google Data Centers site
Follow