TenKsolar, the Bloomington-based maker of solar electric panels, has received a significant equity investment from the GFI Energy Group of Oaktree Capital Management, the big California-based investment group.

Joel Cannon, a founder of the six-year-old TenKsolar, said in an interview late Monday that Oaktree would not permit him to specify the dollar amount but that it was less than the $25 million raised in TenKsolar's first two rounds of private funding, including $15.5 million in 2012 from European and South Korean investors.

Cannon said the investment will make Oaktree a large minority investor in the company and that including subsequent equity and debt funding anticipated from Oaktree, the investment will finance the next stage of TenKsolar's growth and possibly lead to an initial public offering.

Dallas Meyer, the other founder of TenKsolar, a former Seagate engineer and TenKsolar's chief technology officer, said the Oaktree investment "gives our customers confidence that TenK has a long-term financial partner behind us to support our growth."

Ian Schapiro, head of Oaktree's GFI Energy Group, said in a prepared statement: "TenK's innovative solution is an ideal platform for us, as they have created a low-cost, high-density … system well-suited to this [commercial rooftop solar] market.''

In an interview, Cannon said TenKsolar expects to grow from 150 employees in Minnesota and Shanghai, where it also manufactures solar array components, to more than 200 by the end of 2014.

"Our commercial-rooftop system is low-voltage, safe, highly reliable and highly shade-tolerant, and our solar cells all perform independently of one another and offer more energy per square foot of rooftop than any other," Cannon said. "There are things in the pipeline and customers have seen our trials and we're increasing our production capacity to meet demand."

TenKsolar also is a beneficiary of recent state regulatory approval of $42 million in Xcel Energy grants for renewable energy projects. More than 40 percent of the money is headed for 16 solar projects statewide, six of which will be built with TenKsolar technology.

Cannon said the Xcel projects in Minnesota are meaningful but noted that about 85 percent of TenKsolar's installations are outside the state.

Oaktree's GFI Energy Group invests in the electric and natural gas sectors, including renewable energy, and typically partners over several years with the management teams of companies it believes can be grown and take share in their target markets. Oaktree has about $80 billion in assets under management.