Silver Lake has raised $653 million for its Kraftwerk Cleantech fund, up from $302 million in July 2012.

The most recent filing with the Securities and Exchange Commission shows the amount sold is still about $100 million short of the fund’s target of $750 million, although the filing noted the amount sold does not include the general partner commitment.

Silver Lake Kraftwerk was formed by billionaire George Soros, Washington insider Cathy Zoi and Foundation Capital partner Adam Grosser. The super group had originally set the goal of raising $1.25 billion to invest in clean technology, but that was back in 2011 before cleantech investing took a nosedive.

The first quarter of this year saw cleantech venture investments hit the lowest point in four years at $369 million, a 61 percent drop compared to the first quarter of 2012. While some see the downturn as a burst bubble, others just think it’s a shift in the approach to the market.

"We think 2013 will see the first data points of success of the 'next wave of cleantech investing' -- especially rewarding business model innovation over technical innovation. Thus, we expect LP dollars will start flowing back into this huge macrotrend opportunity, starting in 2014-2015," wrote Rob Day, a partner with Black Coral Capital, this spring on his GTM Cleantech Investing blog.

We'll be highlighting this coming trend at the upcoming NextWave Greentech Investing conference on September 12 in Menlo Park.

There's some evidence that this is playing out in the latest round for the Kraftwerk fund.

The Kraftwerk fund made a $40 million investment to take a majority stake in friedola Tech, a German recycled plastics processing company that produces products for the automotive and packaging industries.

As the investment in friedola Tech shows, Silver Lake Kraftwerk is looking for opportunities not only in energy, but also in sustainable resource use. The fund’s website says that it targets companies that “leverage technology and business model innovation to improve energy efficiency, reduce waste and emissions, harness renewable energy, and more efficiently use natural resources, among other applications."

Silver Lake Kraftwerk made an $81 million investment in SolarCity in early 2012.  At the time of the investment, SolarCity had installedsolarpanels on rooftops at about 30,000 sites. Earlier this month, SolarCity announced a goal to have 1,000,000 solar rooftop customers by July 2018.

To learn more about the changing landscape of cleantech and sustainability investing, check out the Next Wave Investing conference.