It wasn't so long ago that photovoltaic solar panels were expensive, hard—and dirty!—to produce, inefficient sources of very expensive power.
In the last little while, however, a flurry of advances have improved on all of those problems. So many announcements have come out lately that I've delayed this post repeatedly due to the sheer quantity of new information. But that's not going to stop, so I'll post what I have now, and I may post again later.
For a super-quick summary of first-generation photovoltaic power, the panels were made of silicon using a process that involves toxic chemicals and high temperatures, were very fragile, expensive, and had a low efficiency and limited lifespan.
But now they're becoming cheap, tough, flexible, easy to make, and remarkably efficient and durable.
Starting with the biggest difference: the new ones are made from plastic, not silicon.
It turns out that contaminating silicon crystals with phosphorus and boron isn't the only way to get a material that has electrons floating around in it when light bumps them loose. There are quite a few polymers which not only work quite well as semiconductors, they can absorb light energy more efficiently, allowing them to be thinner and still capture the same amount of light.
Some of the polymers are also soluble in an appropriate solvent, making them liquid and allowing them to be printed with an inkjet printer, or one of any number of well-established ways of getting a thin layer of liquid stuff in a pattern of your choice on the surface of your choice.
There's a wide variety of polymers, and each one reacts to a slightly different piece of the light spectrum. Some of them are transparent to light at a frequency they don't use, leading to stacking the cells so more of the light's spectral range is used and thus the cells operate at ever higher efficiencies.
There's even a new battery technology using pulp mill waste to store the charge from a solar cell for use at night, which takes advantage of the systems trees use to chemically store energy their leaves gather during the day.
This story isn't finished yet. There are still many things to discover—a better transparent electrode, for example: a solar cell needs electrodes on both sides to transmit electricity, but at least one of those sides has to let light through to the photosensitive material to create that electricity in the first place. Still, there are students making photovoltaics from fruit in a university chemistry class. The ease of production is coming into play, although perhaps not as easy yet as the press releases reprinted by the news media would have you believe: recent news about "paint-on solar panels" that can be applied as your house's next coat of paint may be simpler to create than past solar panels, but as of December 2011 when those stories started appearing, the "paint" needed to be annealed onto a conducting surface at 200C and they could only do small surfaces. Not quite as simple as repainting any old house.
2 comments:
Good post!!! really informative and accurate. the history of solar technologies you provided pays much attention to details, which are not familiar to many people. Here, one current technology you should pay attention to - solar photovoltaic battery with self-cleaning function. The efficiency of energy generation increases at 40% if solar panel has electrosensitive film, which discharges dust out of panel's surface.
Self cleaning panels could help. I know the mars rovers had problems with sand buildup on their backs sometimes, but that was solved the same way it was created - by the wind.
Electrostatic repulsion of dust is parasitic energy consumption; it will be interesting if that method keeps the panel operating at a level that more than makes up for the power lost in keeping it dust free.
Specifically, if it takes (random number out of thin air) 10% of the power generated by the panel to run the self-cleaner, then dust accumulation would have to cause more than 10% loss of power generation for it to be worthwhile. This would obviously depend on what kind of environment the panel is located in.
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