The second quarter wrapped up with a flurry of investment activity last week.

Rumors surrounding smart metering company Elster Group (links require subscription) proved true, as the company has reportedly agreed to be acquired by British private equity firm Melrose for $2.3 billion. The deal has sparked anticipation of further M&A activity involving other smart metering majors.

In venture investing, smart window company Soladigm claimed the top spot last week, raking in $55 million in Series D equity to support commercialization of its energy-efficient glass product. New investor Reinet Investments joined Soladigm’s existing shareholders in the financing.

In an interesting partnership concerning electric vehicle proliferation in China, charging infrastructure company ECOtality last week announced a joint venture with Changchun Eco-Power Technology to build out charging stations in the country. China is widely expected to someday be the largest single market for electric vehicles, but highlighting the fact that few Chinese own their own automobile today or are likely to be in the market anytime soon was an announcement by the companies that the JV will initially focus on airport tarmac fleets.

Solar thin film PV company Abound Solar last week announced that it would file for bankruptcy, making it the latest victim of a PV market recovering from an oversupply and subsequent price drop in silicon PV modules. The US Department of Energy’s Loan Guarantee program had provided a backstop of up to $400 million for the company’s borrowing activities, but Abound had only borrowed against a fraction of that. The DOE insists that American taxpayers will lose little on the deal.

Meanwhile, private investors remained bullish on cleantech as Braemar Energy Ventures announced the close of a $300 million fund for investing in energy technologies.

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