Green Tech

If you need more proof that thin-film solar cells is where the action is going, take a look at the money flow.

SoloPower is raising almost $200 million to ramp up manufacturing of its thin-film solar cells, according to a report in VentureWire picked up by other media outlets.

A diagram showing SoloPower's roll-to-roll solar cell manufacturing process.

(Credit: SoloPower)

The San Jose, Calif.-based company makes cells from CIGS, a combination of copper, indium, gallium, and selenide which a number of solar companies are betting can undercut traditional crystalline silicon.

Thin-film solar cells, from CIGS or other materials, are less efficient at converting sunlight to electricity but use far less material than silicon, making it potentially cheaper.

CIGS cells are also flexible, enabling things like solar rooftop shingles. At the same time, fabricating cells with that combination of materials has been fraught with technical challenges.

SoloPower's hefty funding is the latest to pour into thin-film CIGS solar start-ups.

NanoSolar last month disclosed that it has raised $300 million, bringing its total funding to about half a billion dollars.

Another thin-film start-up, Ava Solar, raised $104 million in equity last week to make cells from cadmium telluride like high-flier First Solar. CIGS maker Miasole is said to be seeking to raise an additional $200 million as well.

These relatively young companies are taking in a lot of money, when compared to companies specializing in things like smart grids. But to be competitive on cost, solar companies need to manufacture high volumes of cells, and building these facilities requires large capital investment.

SoloPower's technology is a roll-to-roll manufacturing process in which CIGS cells are layered on a flexible substrate. It layers the cells through electroplating, rather than sputtering, which is the technique used by hard-drive manufacturers to layer on magnetic material.

SoloPower's series B venture round in July of this year raised $30 million.

A recent report by Greentech Media and the Prometheus Institute forecast thin-film production to double in each of the next three years, with CIGS being the most "exciting yet elusive."

The study forecast that the thin-film cells will cost $1.40 per watt or less, with a 50 percent gross margin, while silicon cells manufacturers' margins could be as small as 15 percent.