The photovoltaic solar cell business is closing in on dire economic straights. The economics for producing power are still far too expensive to compete with – almost all other forms of power generation. When news of a way to cut costs arrives – it matters. Over the long term solar will have a role in generating power, but the best way is to be able to compete fair and square with everything else. Costs have to come down from the cells to the panels, mounts and the system to convert the power for home and business use.
Engineers at Oregon State University (OSU) have for the first time developed a way to use microwave heating, the same type of microwave oven technology that most people use to heat up leftover food, in a new way to make thin-film photovoltaic products with less energy, expense and environmental concerns.
The microwave process synthesizes copper zinc tin sulfide, a promising solar cell compound that is less costly and toxic than some solar energy alternatives. The OSU research paper was published in Physica Status Solidi A, a professional journal.
Greg Herman, an associate professor in the School of Chemical, Biological and Environmental Engineering at OSU explains the cost advantage with, “All of the elements used in this new compound are benign and inexpensive, and should have good solar cell performance.”
The thin-film photovoltaic technologies offer a low cost, high volume approach to manufacturing solar cells. A new approach is to create them as an ink composed of nanoparticles, which could be rolled or sprayed – by approaches such as inkjet printing technology – to create solar cells.
Herman picks up again on the printing point, “Several companies are already moving in this direction as prices continue to rise for some alternative compounds that contain more expensive elements like indium. With some improvements in its solar efficiency this new compound should become very commercially attractive.”
To improve adoptability and further streamline that process, the OSU researchers have now succeeded in using microwave heating, instead of conventional heating, to reduce reaction times to only minutes or seconds, and allow for great control over the production process. This “one-pot” synthesis is fast, cheap and uses less energy, the researchers say, and has been utilized to successfully create nanoparticle inks that were used to fabricate a photovoltaic device.
The OSU team made Cu2ZnSnS4 (CZTS) nanoparticle inks for the first time in a one-pot synthesis method using microwave heating. The precursor solutions were mixed and reacted at 190°C for 30min. A solar cell fabricated with the CZTS nanoparticles had a conversion efficiency of 0.25%. Not amazing but a start.
Herman winds up with, “This approach should save money, work well and be easier to scale up at commercial levels, compared to traditional synthetic methods. Microwave technology offers more precise control over heat and energy to achieve the desired reactions.”
It’s refreshing to see technological advances come in the field of manufacturing technology. A few short years ago the research papers came fast and furious with ever-higher efficiencies that were far too expensive to get to market. Most studies will languish on shelves for years if not decades.
For solar photovoltaic to survive and prosper the costs have to get way further down. Grid parity, all those studies about being about the industry being competitive now taken aside as impractical, remains an elusive goal. Much cheaper cells are a start, but there’s a long way to go.