The expo halls at Solar Power 2007 were buzzing with activity. The many languages overheard on the show floor made SP seem like a global experience.

Here at Solar Power I've been listening for clues about the maturity of the solar industry. Hamm's tip-off was hidden in plain sight. Then SEIA President Rhone Resch said it outright: "It is our time."

Throughout the day I heard other clues. Product announcements include kits and designs that will make it easier to buy and install solar. Manufacturers are thinking about the whole product, not just the components they supply. This indicates a trend I call the "Macintosh effect," which I'll write more about later. In essence, a few customer-driven manufacturers can coerce an entire industry into solutions-oriented product design, and that can make adoption rates explode.

More from Solar Power 2007:

"Solar Power 2007 Round-Up" -- Articles, podcasts, blogs and webinars from the conference.

Marketing savvy is another clue that the industry is coming of age. The conglomerates -- Sharp, Kyocera, BP, Sanyo -- clearly see solar as a significant part of their business now, and their extravagant exhibits show it. Second-tier players are starting to look grown up, with eye-catching exhibit designs, multimedia presentations, and professional relations with the media. There are still the scores of emerging companies, scrappy startups, tiny importers and hopeful inventors. For them, traffic at the expo was no disappointment.

A sense of being grown up is a switch from Hamm's usual message, urging attendees to "wait until next year" for an even better conference -- although she said that this year, too. If the size of the conference is an indicator of maturity, then solar certainly has entered adulthood. Hamm boasted 8,100 paid attendees as of the opening of the conference, and forecasted 10,000 in all.

As the curtain rose on the opening plenary session Tuesday morning, hundreds of attendees were still in line to register and pick up their badges. The auditorium filled quickly to capacity -- I heard 1,800 -- and many more stood and listened from the lobby. The emcee called for a seventh-inning stretch for everyone to move over and make the few empty seats accessible, and crews brought in more chairs.

Exhibitors filled this expo hall and spilled over to a ballroom in the Hyatt next door. Keynote speaker Ray Lane of Kleiner Perkins Caufield Byers -- another prominent technology guru turned cleantech investor -- likened this plenary to his experience of speaking to a packed auditorium at Oracle World 2000 about an up-and-coming database technology. Relating that to the interest in solar and its importance to the world, he said, "You're going to need a much, much larger convention center than this."

The conference has outgrown a few facilities in its short history. Compare the first-year attendance of 1,100 with this year's forecast of 10,000. Solar Power 2008 will be held at the San Diego Convention Center, a facility several times larger than this year's venue in Long Beach.