Toyota installed a 536-kilowatt system in 2003. The solar power provides 20 percent of the power needs of Toyota's south campus complex, a 624,000-square-foot building that's part of the company's national headquarters in Torrance, Calif. On some sunny weekends, the system, installed by PowerLight Corp. in Berkeley, Calif., may generate more power than needed by the building.
The system cost US$3 million, but with state and federal tax credits, the actual cost to the company was about $1.5 million.
Here are four of Yamauchi's takeaways from using solar:
1. With tax credits, the original payback was estimated at about seven years. It's now at about nine years.
"We had an electric rate decrease, so everyone is happy about that except for me," Yamauchi said. "But it's still a good decision for the company," and rates are heading back up.