Google Solar PayBack in 7.5 Years

VANCOUVER - Apr 2/07 - SNS -- Going green makes basic economic sense for most businesses because, unlike, individuals, they can write off the expense of retrofitting buildings.

The case was recently made by Google, which recently rolled out a 1.6 mega watt solar installation involved 9,212 Sharp photovoltaic modules that cover most of the buildings at its California campus and most shaded parking spaces. The installation will generate about 30% of Google's peak electrical demand or enough to light about 1,000 homes.

Google's Anthony Ravitz says the company expects to recover its investment in 7.5 years, after which it will continue to enjoy inexpensive power for decades.

Writing about the move, Ars Technica's Nate Anderson said, "With the company sprawled across a large campus of many low buildings, roof space was easily available. Solar also has the unique property of pumping out more energy when power is the most expensive—peak afternoon hours. When air conditioners across California kick into action on sunny days, Google generates the most power."

Solar installations are expensive, but subsidies from the California's Pacific Gas and Electric utility company and U.S. government tax credits made it easier to commit to the project.

Anderson writes, "The solar modules are wired in series, 14 to each circuit, and their output is sent to 10 SatCon inverters. The inverters transform the DC power to utility-grade AC, and are 96 percent efficient at installation (efficiency drops each year that they are in operation).

"The inverters are then tied into Google's own power systems and the general electrical grid. The system is set up for "net metering," which means that any excess power generated by the panels is pumped back into the state grid and Google receives a credit for that power.'