Greentech Innovations: A Solar Cell the Size of a Red Blood Cell

Bloo Solar says it will shrink the size of solar cells down—waaay down.

The West Sacramento, Calif.-based company has devised a 3-D solar cell that’s about the same size as a red blood cell, says CEO Larry Bawden. The cells will be packaged in arrays and panels in a way that will, according to the company, drastically reduce the cost of solar cells while increasing the efficiency.

“The biggest challenge is pinholes” in the underlying substrate, said Bawden. “We call it ultra, ultra, ultra thin-film PV.”

Bloo’s first solar cells will use cadmium telluride, but it’s also possible to make them with copper indium selenide or CIS, according to Bawden. (Bawden will further outline the technology at Greentech Innovations: End to End Electricity on November 18 in New York.)

What’s going on here? The solar cells are tiny nano-scale bristles. The outside of the bristle holds the active solar materials. The material is electroplated onto a conductive post. Light strikes the bristles, electrons are extracted from the light, and then ferried away by the conductive post.

The efficiency will be higher than conventional solar cells because the structure of the bristles, combined with how they are spaced and arranged in relation to one another, allow a solar panel to trap more light than normal. The structure of the cells also prevents electrons extracted from the light from recoupling with positive charges.

“It traps more light than anything out there,” he said.

The 3-D nature of the bristles also means that it can harvest light during the early and late hours of the day, something planar solar cells can struggle with. Bloo in some ways is combining a number of trends into a single product: the popularity of cad tel, reducing the cost of thin-film solar cells, using 3D structures to extend the active time of solar cells like Solyndra and better light trapping. (Denmark’s Sunflake is trying something similar with III-V materials.)

The technology, which was created by professors at UC Davis during a leave at the university, is currently in the testing stage. Bawden said the company hopes to share some results from its lab work and move into commercial production by 2011 or 2012.