Winter is approaching in the southern hemisphere, making sunshine a diminishing commodity for the next few months. Undeterred by this impending seasonal abridgment of daylight, Australian scientists have just announced a solar energy innovation: a process to print solar cells using a variation of an ink-jet printer. Well, it's a $200,000 variation, so I don't expect to be printing photovoltaic cells in my basement any time soon. Nonetheless, the process makes it economical - at least from a manufacturing standpoint - to put inexpensive PV cells where they wouldn't otherwise be feasible. Their research was sponsored by CSIRO, Australia's national science agency, in collaboration with the University of Melbourne, Monash University, and several industry partners.
In 2011 MIT developed a similar process, but theirs involved multiple passes using a different mask for each pass, and required a vacuum chamber. The CSIRO process is more like silk-screening an image onto a T-shirt. Semiconductor ink is sprayed onto a substrate - thin plastic or steel - making a product that can be laminated onto a surface or built directly into construction materials. Dr. David Jones, the project's lead researcher, envisions buildings with these cells laminated onto the windows and built into the roofing material. On a smaller scale, the plastic version could be added to portable devices, allowing them to be powered in part by solar energy, prolonging battery life. The scientists expect to produce cells at a retail cost of $1 per watt when materials are purchased on a production scale.
Dr Scott Watkins, CSIRO materials scientist, holds a sheet of solar cells printed using this process. (Image: CSIRO)
Current production cells are printed on an A3 sized substrate (420 mm x 297 mm) and deliver between 10W and 50W per square meter, making them about 1% to 6% efficient. (PV cells are typically rated based on a solar irradiance of 800 W/m2.) On smaller cells, the process has reached 80 W/m2 (10% efficient). By comparison, a polysilicon PV cell is about 16% efficient, but considerably more expensive to manufacture, very heavy, and extremely fragile.
Engineers, what devices are you designing that might use an inexpensive PV cell like this?