Ink-Jet Technology Can Print Cheap Solar Panels

Posted by Sarah Laskow

Inkjet droplets
The two most important variables for making solar panels ubiquitous are the panel’s efficiency and their cost. A group of researchers at Oregon State University think they’ve found a way to cut costs dramatically: they developed an ink made up of solar-capturing elements that they can print onto solar panelsjust like regular people print out documents from their computer. Now they just need to find a way to make the resulting panels more efficient.

The first solar cells and most solar cells on the market today use crystalline silicon as their base. The most efficient of those cells panels convert about 20 percent of the sunlight they capture into electricity. But they’re expensive, and in the last decade, researchers have been working on a different magic mix of elementscopper indium gallium selenide or CIGSthat could make solar panels cheaper. That’s the substance that the OSU researchers focused on.

The materials themselves are still relatively expensive, but inkjet technology can minimize costs. Traditional solar cell manufacturing methods end up wasting expensive materials. But inkjet printers can deposit the CIGS-based ink onto the solar cell substrate in exactly the desired pattern. The OSU team says the technique they developed will reduce the waste of raw materials by 90 percent.

The resulting cells, however, only convert sunlight into power with 5 percent efficiency, not high enough for the cells to be commercially viable yet. In theory, CIGS-based panels could be enormously efficient: advocates like the OSU researchers point out that a thin layer of this material can capture sunlight as efficiently as a silicon-based cell 25 times as thick. The next step to improving the inkjet printing technology is to make the resulting cells more efficient; CIGS-based solar panels produced by traditional techniques reach efficiency levels as high as 18 percent.

Without increased efficiency, ink-jet printed solar cells have little chance of catching on, even if they are cheaper to produce. Konarka Technologies, a Massachusetts-based company, figured out how to print solar panels back in 2008. But those printers used a third type of solar material, one based on organic materials. Like the OSU technique, the Konarka cells promised to be cheaper than traditional silicon-based cells. But the company has been having a hard time finding a foothold in the market for its products, some of which have a power conversion efficiency of only 2 percent.

The OSU panels are more promising. This is the first time anyone has succeeded in printing out a CIGS-based panel at all, and it's already more efficient that Konarka's printed panels. The OSU team believes that it will be able achieve 12 percent efficiency with the ink-jet technique it developed. And even if the resulting cells aren’t as powerful as the panels gracing rooftops or spreading out in solar farms, they could be more easily and cheaply incorporated into consumer products, making it that much more likely that every little gadget will have a solar panel incorporated into its design.

Photo courtesy of flickr user Engineering at Cambridge