Innovative Use of Plastics Could Cheaply Double Solar Cell Output 141
doug141 writes "In standard solar cells, much energy is lost (as heat) from photons mismatched to the capability of silicon to capture them. A new technique uses a pentacene layer to down-convert each hot (un-captureable) electron to two electrons that can be captured by standard silicon cells." You can read more at the University of Texas research group's web page.
Re:Power companies (Score:5, Informative)
The power companies won't mind if solar is used for large-draw things like daytime AC, when they themselves have to buy power at peak rates. They'd actually become more profitable with less demand.
The use for night-time heating is a solved problem - store the heat in something massive during daytime hours - you don't even need to take the losses from converting to electricity and back.
Re:Improving solar cells (Score:5, Informative)
Sure they do [wikipedia.org].
There are two problems though:
1. That somebody in a lab figured out a way to make a cell 15% more efficient doesn't mean it's going to be manufactured tomorrow.
2. 15% more efficient means "15% more efficient than what we started with". This means "We took a cell that coverts 15% of the Sun's energy into electricity and made it covert 17.5%", not 30% as people seem to expect.
Vindicated (Score:3, Informative)
This effect has been known theoretically for quite a while, and experimentally for a few years at least. Look up the literature on "singlet fission" or "multiexciton generation." The process works by photon excitation to a singlet excited state, followed by the reversion of that excited state into 2 triplet excited states with roughly half the energy. Thus the extra energy that would normally be lost as heat can go into exciting another photoelectron. The neat thing about this paper is that, for the first time, the researchers were actually able to show a >100% photoelectron generation, meaning that they got more electrons out than photons that they put in. This is a huge vindication to this direction of research, which has recently been seeing quite a bit of skepticism as to its legitimacy (since not having greater than 100% photoelectron generation can be explained away by other possibly competing processes, but the result from Zhu's lab pretty much nukes those competing theories).
Re:Improving solar cells (Score:3, Informative)
the cost of solar has been reducing quickly.
I quoted a twice, from the same company, 1 year apart. the second quote added almost 30% capacity for the same price, after only 1 year.
times they are a'changing.
Re:Power companies (Score:5, Informative)
That's an insanely ignorant suggestion.
That would incentivize people to move their power usage from off-peak times to on-peak times, forcing power companies to build *more* capacity for on-peak utilization. The pricing you describe is the *exact opposite* of the actual economy of the power industry, and any company that tried it would end up out of business.
The fact that solar only generates during the day makes is a boon for power companies, it prevents them from having to build expensive plants for peak production while leaving lots of profits in providing baseline power with existing investments.
Re:Power companies (Score:5, Informative)
Now many states have have laws requiring essentially that the power company buy or give you credit for anything you produce. So you get the panels installed and apply for a two way meter from the electric company. They keep track of how much you produce and subtract it off your consumption essentially.
Furthermore, some states require utility companies to use so much power from solar, and this is done essentially by buying credits from people making solar. So in NJ if I have 10 kW worth of panels I might generate enough credits in a year to sell for $6000. It is essentially the state dictating that the power company has to pay me money for making solar energy. That is on top of the savings you get from using less electricity.
So with federal rebates, a 10 kw system costs around $35k to $40k to install. But with the credits and electricity savings, it will "pay for itself" in 5 years or so.
In NJ this fell apart a little bit because everyone saw it was a good deal and there is now an oversupply of these credits, so the value of the credits are less than half of what they were last year. Time will tell how it all shakes out. If I got no money for the credits, the panels should pay for themselves in 20 years. So it will be somewhere between a ton of free money and a marginal investment.
Re:Power companies (Score:4, Informative)
It's not tradeable in the UK, either - what we have here is called a "feed-in tariff", which is a government set price per KWh that is paid for a fixed period.
The UK solar "industry" (read: the hucksters who jumped on this money tree when it first came in) are now bleating because the FIT has been halved (though it's still 30 cents or more per KWh), and their business model is no longer profitable.
Would be so much better if there was a market in the tariffs, and the solar option could then grow at a sensible rate.