Cathy Zoi has joined C3 as its Chief Strategy Officer following her work with Silver Lake clean energy fund Kraftwerk. She was formerly the acting under secretary for the Obama Administration.

Former Obama administration energy policy maker Cathy Zoi has joined Tom Siebel’s energy software startup C3 as Chief Strategy Officer, following a stint as an investor at Silver Lake Kraftwerk, Silver Lake’s clean energy growth fund. Zoi is now listed on C3’s website, is no longer listed on Silver Lake Kraftwerk’s site, and her bio on C3 says most recently she was a partner with the fund.

C3 is a four-year-old startup that develops data grid analytics tools for utilities like PG&E, and is the software behind GE’s Grid IQ Insight product. The company was founded and is led by Siebel System’s Tom Siebel, and had been largely in stealth mode until earlier this year when it talked a bit about its smart grid plans at theDistribuTECH event in February. Previously C3 had focused more on collecting data about corporations’ carbon emissions and energy, but has seemed to veer away from that in recent years.

C3’s current big data software platform collects disparate data about buildings, energy generation and energy consumption from a variety of places like publicly-available data scraped from the web, utilities’ energy use info from its customers, and weather data from weather information companies. For PG&E, C3 aggregated at least 8 terabytes of data, which C3 normalized and loaded at 500 million records an hour. The data product helped PG&E do a year’s worth of energy audits on the commercial and industrial buildings in its footprint, said Siebel at DistribuTECH.

C3 plans to launch another five projects like this in 2013 and another five in 2014, and its other customers include Entergy, Northeast Utilities, Constellation Energy, NYSEG, Integrys Energy Group, Southern California Edison, ComEd, Rochester Gas & Electric, and DTE Energy.

Silver Lake Kraftwerk is private equity firm Silver Lake Kraftwerk’s clean energy growth fund, and it has a thesis to invest in later stage growing clean energy, waste and other types of cleantech companies. The fund, which also is looking to invest aggressively internationally, has raised at least $350 million, though I’ve heard the fund is closer to having raised $600 million at this point. Silver Lake Kraftwerk has invested in a later round in SolarCity (before it went public) and German recycled plastics processing and manufacturing company Friedola Tech.

Zoi spoke at our Green:Net event back in 2011. She also joined the Board of Makani Power, the high altitude wind power startup in Alameda, Calif.