Slashdot Mirror
MIT Develops Ultra Thin, Light Weight, Efficient Solar Cells (blastingnews.com)
MarkWhittington writes: Researchers at MIT have developed a gossamer thin solar cell that is made of layers of flexible polymers. The cell is so light that it can rest on a soap bubble without breaking it. As a bonus, the thin, light cells puts out 400 times more power than the standard, glass covered photovoltaic cells, at about six watts per gram. According to the researchers, this new development could help power the next generation of portable electronic devices.
https://en.wikipedia.org/wiki/Operation_Plumbbob#Propulsion_of_steel_plate_cap
Watts per square inch is more important. If I have a ultrathin solar panel and it gets that many grams/watt it probably takes a huge surface area to get that power.
You need to read the article to understand why it's an advance. For 1 the process itself creates clearer cells hence an increase in efficiency. It you want to compare conventional cells to this one you need to have comparative data as you mentioned which we do not have. In their application watts per grams is ideal because their current intended use is on flying objects such as weather balloons. Here's the part of the article:
While the solar cell in this demonstration device is not especially efficient, because of its low weight, its power-to-weight ratio is among the highest ever achieved. That’s important for applications where weight is important, such as on spacecraft or on high-altitude helium balloons used for research. Whereas a typical silicon-based solar module, whose weight is dominated by a glass cover, may produce about 15 watts of power per kilogram of weight, the new cells have already demonstrated an output of 6 watts per gram — about 400 times higher.
"Clearer cells" does not mean an increase in efficiency, in fact it means just the opposite. A clear solar cell is not absorbing a significant amount of light (or at least if it is, it is not producing a significant voltage, and hence not much power), whereas conventional opaque solar cells absorb extremely efficiently in the part of the spectrum where the sun produces the most photons.
Furthermore, the W/g comparison from the article is utterly meaningless. A solar cell made from a 180-micron-thick silicon wafer can't survive the elements without encapsulation, hence the heavy glass sheet for terrestrial solar modules. Even solar cells launched into space are protected by a polymer encapsulant and a glass sheet (though both are much thinner and lighter than for a terrestrial module). Implying that you can replace a fully encapsulated solar module with a completely unprotected polymer solar cell 1/10th the thickness of a sheet of cellophane to is like saying you can replace a boat's sail with a sheet of gauze and steer your way through a gale. Sure, maybe the cell does put out more W/g than a conventional cell, but quantifying the claim like this makes them look dishonest.
Finally, to date, organic solar cell degrade rapidly when exposed to light -- so rapidly that organic cell researchers have been known to transport their cells to certification labs in light-tight boxes and supervise their efficiency measurements to ensure the cells are not needlessly exposed to light for even a few minutes. Add the high-radiation environment of space to the mix and you aren't likely to see these cells being shot into space anytime soon. Not to mention that even undegraded the cells are only 2.3%-efficient. The cells used in space applications are already significantly lighter than the structures they're mounted on, so cutting the efficiency by more than a factor of 10 is likely to result in increased weight no matter how light the cells are.