Should you spring clean your solar panels?

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

Search Options now on Google Images

A few months ago when we announced the Search Options panel, we promised that you would soon see similar functionality across our other search properties. Today we are rolling out Search Options for Google Images.

This new feature offers quick access to existing tools, including search by color and image type. Color search will find images that are only in color or only in black and white, or even images that contain a specific color, such as red, pink, or green. Type search is a great way to narrow down your results if you are looking for a specific kind of image, such as a photo, clip art, line drawing or face.

We've also revamped our size search. In addition to choosing from commonly searched-for sizes, now you can search for an exact image size or any image larger than a certain size. You can find images of practically any size, including 70 megapixels or more.



The new layout makes it faster and easier to combine and toggle between options. It also makes it easier for us to add additional image search options in the future, so keep your eyes peeled. Just click "Show options..." in the blue bar on the search results page to try out any of these tools.

Posted by Ken Dauber, Software Engineer, and Nate Smith, Associate Product Manager

I now pronounce you monetized: a YouTube video case study

(Cross-posted from the YouTube Biz Blog)

Last week the world watched in wonder as Jill Peterson and Kevin Heinz's wedding party transformed a familiar and predictable tradition into something spontaneous and just flat-out fun. The video, set to R&B star Chris Brown's hypnotic dance jam "Forever," became an overnight sensation, accumulating more than 10 million views on YouTube in less than one week. But as with all great YouTube videos, there's more to this story than simple view counts.

At YouTube, we have sophisticated content management tools in place to help rights holders control their content on our site. The rights holders for "Forever" used these tools to claim and monetize the song, as well as to start running Click-to-Buy links over the video, giving viewers the opportunity to purchase the music track on Amazon and iTunes. As a result, the rights holders were able to capitalize on the massive wave of popularity generated by "JK Wedding Entrance Dance" — in the last week, searches for "Chris Brown Forever" on YouTube have skyrocketed, making it one of the most popular queries on the site:


This traffic is also very engaged — the click-through rate (CTR) on the "JK Wedding Entrance" video is 2x the average of other Click-to-Buy overlays on the site. And this newfound interest in downloading "Forever" goes beyond the viral video itself: "JK Wedding Entrance" also appears to have influenced the official "Forever" music video, which saw its Click-to-Buy CTR increase by 2.5x in the last week.

So, what does all of this mean? Despite compelling data and studies around consumer purchasing habits, many still question the promotional and bottom-line business value sites like YouTube provide artists. But in the last week, over a year after its release, Chris Brown's "Forever" has again rocketed up the charts, reaching as high as #4 on the iTunes singles chart and #3 on Amazon's best selling MP3 list. We've seen similar successes in the past with partners like Monty Python.

One of our main goals at YouTube is to help content creators effectively make money from the distribution of their content online. That they can do so in a way that brings artists and our community together to create fun, spontaneous and inspiring works, is one of the best and most exciting things about YouTube.

Posted by Chris LaRosa, Technical Account Manager, and Ali Sandler, Music Partner Manager