Research may yield thermo PVs without mirror arrays

December 05, 2011 // By Jean-Pierre Joosting
MIT researchers are theorizing that using an array of precisely spaced microscopic holes to concentrate sunlight in thermophotovoltaic devices would potentially make for simpler and less expensive systems than systems that depend on mirrors.

The sun’s infrared radiation would enter the chip through the holes on the surface, the reflected rays would be blocked by a precisely designed geometry that only allows rays that fall within a very tiny range of angles to escape, while the rest stay in the material and heat it up.

“This is an alternative to concentrators,” said Massachusetts Institute of Technology researcher Peter Bermel.

According to Bermel. the system would be simple to manufacture using standard chip-fabrication technology, unlike fabricating mirrors used in traditional concentrating systems, which require “extremely good optics, which are expensive.”

Bermel will be testing different materials for maximum power efficiency. With this angular-selective approach, he is anticipating possibly some 35 percent efficiency, which would be higher than the theoretical maximum by traditional photovoltaic solar cells.

Bermel’s research is still theoretical. Next steps are to build prototypes.

The new device was described in a paper by Bermel and other MIT researchers, published in the October Nanoscale Research Letters journal.