The cleantech sector may never see investment intensity like it did in 2008 ($7.5 billion in 350 deals), but there's still activity, and, anecdotally, this reporter is seeing an upswing in investments (it could just be the rush to close deals in advance of the vacation season).

We also see VCs looking for new ways to invest in the energy economy. Here's a roundup of cleantech venture capital funding over the last week:

Swedish solar startup Sol Voltaics and its gallium arsenide (GaAs) nanowires collected a $6 million conditional loan from the Swedish Energy Agency (SEA), Sweden’s national authority for energy policy issues. Sol Voltaics also added Erik Sauar, former CTO at solar manufacturer REC, as an investor -- and is in the process of raising another VC funding round. Sol Voltaics plans to use gallium arsenide (GaAs) nanowires to create another absorber layer on top of existing solar cells to extract more light and raise efficiency by 25 percent -- an enormous stride, as far as solar efficiency numbers go.


Solexel, an advanced silicon solar cell startup, just raised $14.7 million from undisclosed investors, according to an SEC document  It was the third close of the company's now $51.3 million C Round, according to the firm. Previous investors include SunPower, KPCB, Technology Partners, DAG Ventures, Gentry Ventures, Northgate Capital, GSV Capital, Oak Hill, Ecofin, and Spirox. The firm's Board of Directors are Mehrdad Moslehi and Michael Wingert of Solexel, as well as John Denniston of KP, Ira Ehrenpreis of Technology Partners, Doug Rose of SunPower, Les Vadasz of Intel, and Greg Williams of DAG Ventures. Gentry Securities has been enlisted as a placement agent in this and previous fundraising efforts. Gentry's investments include Fisker, Bloom Energy, Amyris, Agrivida, and Glori Energy -- all Kleiner Perkins portfolio companies. The startup's total VC funding to date is north of $150 million. Solexel has also scored $17 million in DOE and NSF grants.


Solar startup Scifiniti just revealed its technology as well as a $10 million round B for its kerfless solar silicon and materials technology. Funding comes from Alloy Ventures, Firelake Capital Management, I2BF Global Ventures and Peninsula Ventures. Total investment raised to date is approximately $20 million. The 22-employee startup's expertise lies in substrate creation, silicon deposition and recrystallization with potential applications in batteries, optoelectronics and ceramics. But the first application is solar. Scifiniti (formerly IPV) deposits a thin silicon layer on a metallurgical-grade silicon substrate in the standard wafer form¬factor. A barrier layer is deposited to prevent impurities from migrating from the sintered substrate into the recrystallized silicon layer; it's 30 to 40 microns thick at 0.5 grams of silicon per watt. 


Skyonic, a Texas-based firm that captures carbon dioxide from power plants and turns it into baking soda and chemicals, has just closed a $128 million Series C round of funding.  The round brought in Cenovus Energy, Bluecap Partners, Toyo-Thai Corporation and Energy Technology Ventures as new equity investors. These firms were added to the list of previous big-name funders, which included Berg & Berg Enterprises, Northwater Capital Management, ConocoPhillips, BP Ventures, PVS Chemicals and Zachry Corporation.


LED networking firm Isotera offers contactless connection of LED lights. The startup just raised $2.4 million from angel investors such as Qi3 Accelerator, the Low Carbon Innovation Fund (LCIF), Synergy Energy, Martlet, and members of London Business Angels, Cambridge Angels, Cambridge Capital Group and Surrey Investment Club.


Bloo Solar just raised $6.8 million for its alleged cadmium telluride (CdTe) solar absorber and "solar-brush" technology. More on CdTe solar firms here.