Unevenness is a real issue for solar power, but it’s mitigated by two factors. First, usage tends to be much lower at night than during the day, anyway, so unless you’re planning on using solar as your sole source, the lack of power at night isn’t that big a deal. Second, while solar is inconsistent even during the day, one of the biggest consumers of electricity is air conditioning, which can get away with running intermittently, and which is in general less needed on cloudy days.
I meant the extra cost of building and maintaining the tracking system will not be justified by the marginal improvement in efficiency. But for a stand-alone (off-grid) solar power system, I think the considerations are a little different and perhaps a tracking platform can be justified.
According to this recent discovery, noise-induced quantum coherence should permit solar panels to reach 27% efficiency.
About 20 years ago, I studied solar energy for a college class essay. From what I recall, it didn’t look very encouraging. At least not back then.
Suppose you could carpet the roof of your one-story house with solar panels, and get enough power to run your whole house.
Now, suppose you have a two-story house or office building. This doubles the available floor space without increasing the roof space. So the same area of solar panels would have a harder time supplying a two-story building with adequate power. Okay, so maybe it’s possible, but I came away with the impression that it would be pushing the limits.
Now, suppose you have a five-story office building. Now you’ve quintupled the available floor space without increasing the roof space (compared to a one-story building with the same footprint). No way you’re going to get solar panels on the roof to cope with that.
Now, suppose you have a ten-story office building, or a 20-story office building. No, wait… Don’t even bother supposing that. Fugeddaboudit. No way you’re going to power that with solar energy – unless you pave some large swath of the Mojave Desert to do so.
Basically, to provide solar power for a n-story building, you need something on the order of n times the area of the building’s footprint, to be paved with solar panels. So I’m not seeing how the nation’s Interstate highways would have enough area to power a major metropolitan area like Los Angeles, which has quite a few n-story buildings.
Now, the technology may have improved vastly since I last looked into this 20 years ago. (I sure hope so.) But unless there have been major breakthroughs or major new technologies, there were very narrow theoretical limits on the amount of power you could get from solar panels – at least, from photovoltaic panels.
You’ve read up-thread that sunlight casts some 1KW/m[sup]2[/sup]. But it turns out that photovoltaic panels can only capture some small percentage of that. I think it was about 12% when I studied it. deltasigma says new results might yield 27%. That’s impressive, if true. Photovoltaic power relies on quantum mechanical effects, in which photons knock electrons out of their atoms, and this is very heavily dependent on the wavelength of the photons. So right there, you are limited to a very narrow spectrum of sunlight that can be captured photovoltaically. Research was focused on finding better silicon doping mixtures that could capture a little wider spectrum of sunlight, but I think that could only go so far. I haven’t looked at deltasigma’s link yet, and I’m wondering already if it involves a better silicon doping recipe, or some really new technology.
The other major solar technology involves smoke and mirrors. Or oil and mirrors. Here, you have parabolic mirrors with tubes of oil at the focus. Mirrors focus sunlight on oil; oil heats up (oil being much better than water at soaking up the calories); oil is circulated to a heat exchanger where it boils water for a turbine or is otherwise put to good use.
This is brand new. It’s essentially coherent light transmission, but the coherence is created by the interaction of the noise in the system and the topology of the components they’re using to trap and move electrons - at least that’s what I think is happening. It’s a pretty dense article and not really having an honest to god science background I was shuckin’ and jivin’ through most of it.
Okay, I just skimmed the whole article. It’s definitely way over my head. But I got some impressions about what they’re saying. Some serious ignorance fighting going on here!
Yes, it seems to be a new technology, distinct from the silicon n-p based photo cells. They are studying quantum biology, specifically quantum effects in photosynthesis, and developing artificial technologies to mimic photosynthesis. I gather that the basic ideas were long known, but harnessing it is rather new. When I studied solar energy 20 years ago, I didn’t come across any talky-talk then about research to mimic photosynthesis. The take-away about coherent light is that, photosynthetic organisms manage to do without artificially generated coherent light (lasers), and now the scientists are learning how that works and how to do the same artificially, using just natural sunlight.
I didn’t quite get that this will yield 27% efficient capture of sunlight energy. The article seems to say that they predict a 27% improvement in yield, without saying: Improvement over what? Maybe the intended audience of this article are people who will know exactly what that means.
That’s a lot of ground covered.
Area of the entire Mojave desert -25,000.
You may not see it but if given that 10,000 square miles (100 by 100) of high quality solar power could power the entire United States, that 61,000 could, theoretically, do it.
Practical, no.
But as a matter of practicality the place of solar is to be part of a mix of resources, not solely solar, which would sorely provide.
BTW Semprius, backed by Siemens (not known for blowing smoke) claims a 33.9% efficiency panel. “That’s more than double the most efficient conventional photovoltaic (PV) module on the market, where performance tops out at 16 percent.” It’s built of cells that have been confirmed by the NREL to have individual efficiency of 41%.