Advanced Technology Ventures on Wednesday announced it has made two new greentech investments, putting money into solar and thermal-cooling companies.

The solar-cell company, Wakonda Technologies, is developing a material that the company claims could greatly improve a solar cell’s ability to convert sunlight into electricity.

Wakonda raised $9.5 million in its first round of funding from ATV, which led the round, General Catalyst Partners, Polaris Venture Partners, Applied Ventures and the Massachusetts Green Energy Fund, which is also a Greentech Media investor.

The three-year-old company, based in Medford, Mass., wants to find a way to imitate the efficiency of solar cells made for satellites while keeping manufacturing costs low.

Solar cells made to outfit satellites use a different class of semiconducting materials, such as gallium arsenide, that can convert sunlight much more efficiently than terrestrial solar cells. Satellite-bound solar cells can convert 30 percent of the sunlight that hits them into electricity, according to Wakonda. In comparison, the most efficient cells commercially available for use on Earth today claim a 22 percent efficiency.

But the ultra-efficient cells for the sky are too expensive for the commercial market today. Wakonda believes it can find a way to make gallium-arsenide cells that offer the similar high efficiency without the high cost.

The company said it is developing what it calls a “virtual single crystal” technology that uses a special surface treatment to cause a commercial metal foil to simulate the performance of the costly single-crystal wafer.

Wakonda has been working with the Rochester Institute of Technology, Cornell University and the NASA Glen Research Center to develop its technology. Wakonda Chief Technology Officer Ryne Raffaelle leads the NanoPower Research Lab at Rochester.

ATV also led the round for the thermal-cooling company, Nuventix.

The company raised $14 million to market its SynJet technology, which keeps lighting and electronics from overheating by blowing bursts of highly turbulent air.

Braemar Energy Ventures participated in the round.

Nuventix, based in Austin, Texas, began producing the SynJet devices earlier this year.

Nuventix currently sells its products to the light-emitting diode (LED) market. LEDs, which traditionally have been used for indicator lights on consumer electronics, have been entering into broader industrial and consumer markets. They can consume a third less power than traditional lights, but are more costly.

Another challenge is that LED lights can burn hot, especially in industrial applications. That makes engineering brighter LED lights difficult. By using a cooling technology, LED lighting makers can improve LED performance while minimizing overheating.

Using SynJet, customers can double the light output from an LED device while keeping the temperature at the same level, Nuventix CEO Jim Balthazar said.

Nuventix’s customers include Philips Lighting, a division of the consumer electronics giant, the Royal Philips Electronics in the Netherlands. Other customers include Cooper, Focal Point, Intematix and Luminus.

Nuventrix also is pursuing customers in the computer industry. Computer makers typically build fans into their products for cooling, but fans can be noisy. Nuventix is working with computer makers to put SynJet into servers, which could reduce their power use by 50 watts, Balthazar said

Balthazar declined to name the computer makers, but said his company may begin selling its devices to server makers next year.

Nuventix was founded in 2003 at Georgia Institute of Technology, and it has raised a total of $29 million (including the $14 million funding).