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Stanford's New Solar Tech Harnesses Heat, Light
An anonymous reader writes with this excerpt from a Stanford news release:
"Stanford engineers have figured out how to simultaneously use the light and heat of the sun to generate electricity in a way that could make solar power production more than twice as efficient as existing methods and potentially cheap enough to compete with oil. Unlike photovoltaic technology currently used in solar panels — which becomes less efficient as the temperature rises — the new process excels at higher temperatures. ... 'This is really a conceptual breakthrough, a new energy conversion process, not just a new material or a slightly different tweak,' said Nick Melosh, an assistant professor of materials science and engineering, who led the research group. 'It is actually something fundamentally different about how you can harvest energy.' And the materials needed to build a device to make the process work are cheap and easily available, meaning the power that comes from it will be affordable."
The abstract for the researchers' paper is available at Nature.
What I want to know is what mechanisms are causing their Gallium-Nitride junction to conduct more reverse current above 227 C.
They are currently projecting operating at 200 C for max efficiency but if it's as I suspect -- increased current flow with higher temperature -- then they can modify the doping mixture to get even higher temps and therefore higher efficiencies.
This would also boost the Carnot Cycle efficiency limit for the secondary heat exchanger that operates after the GaN primary power generation.
I'm reading from the slides.
http://www.solarbuzz.com/Moduleprices.htm
Can anyone point me to a good cost/watt chart over time? I would love to be able to see how prices have dropped over the past two decades. I keep hearing that solar has to drop in price... but have no baseline to judge our progress.
It depends on what you want: space solar panels are the most expensive multi-junction technology, but achieve the highest efficiency.
If you're a huge company, you can get really great deals because you purchase whole manufacturing runs. This is also why it's hard for an individual to buy direct from any manufacturer: all their production capacity is probably already bought up by large companies, so you get the "seconds," the panels that those resellers decide they would like to sell to you (at a price mark up, of course).
Here are some panel price charts, though they're not perfect:
http://www.solarbuzz.com/Moduleprices.htm
http://futurist.typepad.com/my_weblog/2007/08/solar-energy-co.html
But I should point out the bias on these sites: they're in the industry, not independent review sites. So they will be competing to drive your dollars to their products.
Compete with oil? I'm going to guess that they mean with coal, as oil is rarely used as a fuel for power generating stations. Coal and natural gas, yeah, oil - not so much. In the U.S., anyway, only around 1% is generated by petroleum, whereas coal is about 45% and natural gas is about 23%.
Continue reading:
Melosh calculates the PETE process can get to 50 percent efficiency or more under solar concentration, but if combined with a thermal conversion cycle, could reach 55 or even 60 percent – almost triple the efficiency of existing systems.
Roof top glass enclosures (solar hot water) nearly achieve this all by themselves in some sunny locations. http://en.wikipedia.org/wiki/Solar_thermal_collector
Its contained in the collector. Its so hot you generally have to mix with cold water for household use.
Sig Battery depleted. Reverting to safe mode.
Actually lots of it has. PV arrays are far more efficient now than even ten years ago, and the technologies around heat-based concentrators is also far advanced. There are parts of the country where its affordable to run a house entirely off solar -- something not possible a decade ago.
Just because the whole world hasn't converted doesn't mean the innovations aren't making it to the market, it just means even doubling efficiency hasn't helped make it cheaper than oil.
There is a big gap between lab results and making a product out of it.
1. There is the price to produce.
2. Are the materials robust enough for real life.
3. Is the research funded by an organization who will actually give it to industry. Oddly enough there are some groups who are so Anti-Business after there research is done they don't want to sell it to a big company as they would be selling out.
4. Can the technology be reproducible.
5. Is it safe.
There are a lot of details to be worked out.
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Call me when I can pick it up at Home Depot.
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Impractical for personal residence deployment and use, but I'd certainly call a big solar power generation station providing energy "everyday use". Or at least, I'd like for it to be an everyday use. Much like efficient windmills are much too large for my backyard, yet provide me with clean energy everyday.
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So if you could reflect the heat to generate power and use photovoltaics to generate power, could you also create them translucent to some spectrum of light? Then you could grow crops under the solar array, use the array for water capture so the irrigation would hold water better and provide power and temperature maintenance. This idea only works if photovoltaics and plants uses different spectrum to generate power/photosynthesize.
Thermoelectric looks obvious, doesn't it? A few years ago I thought how convenient it would be to use the waste heat from my Diesel boat heater to generate electric power, and I contacted a manufacturer. The reply I got was "we're not even going to quote you because it's insanely expensive". Apparently thermoelectric generators are so expensive they only make sense on things like trans-Siberian or Alaskan gas pipeline monitors, where there isn't enough light for a solar PV supply and the cost of miles of environmentally resistant wiring would be even more prohibitive. Although Peltier generators are cheap, they are hugely inefficient - and even more inefficient in reverse. It would have been cheaper to cover the entire deck in solar panels.
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I live in one of the better parts of the country for solar power, and an installation would cost more than $15,000 to even begin to be practical.
What part of the country is this where putting 15 grand in to your house is such an outrageous sum? A new roof, HVAC, siding, remodeling a room.. pretty much anything you do to your house is going to have a similar cost. And I guarantee none of them would give you the same return until you sell the house.
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Ditto. I'm getting truly sick of these "improvements in solar technology" stories that turn out to be little more than research lab oddities, penny stock scams, or something so expensive that it will never be commercially viable.
When it looks like Joe-Bob can buy a system for under a thousand at Wal-Mart, and the system is so idiot proof, that even Joe-Bob can plug it in and make it work without killing himself or burning down the trailer, you have something.
Until then, even if it works, solar is still just a rich man's toy.
Solar energy. It's NOT just a technical problem. It's an economic problem.
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Solar array costs per watt have dropped considerably, but an array still costs an arm and a leg.
here are some reasons:
- Enough batteries to keep your freezer frozen through the night and maybe a couple cloudy days is expensive.
- Labor costs of installation are 25-50% of installation costs, but if you don't get it installed and inspected by the proper people, your home owners insurance will probably be canceled.
- It's very expensive to install enough panels to power multiple computers, multiple TV's, ACs, Fridges, Microwaves, and a multitude of other electronic devices. Customers need to reduce their power consumption before investing in a solar array.
- Tying your solar array into the grid is expensive. you can't just dump power into the grid. it has to be clean and in phase with grid power, and has to be installed by a certified electrician. (btw it's not just THE grid, it's the power companies grid. They tell you when you can use it. If the power goes down in your neighborhood they will turn off your inverter, because they need the lines powered down when the linemen are working on them.)
Labor costs are not going to go down drastically, so i don't know how much cheaper it can get to the end user. in addition, it seems that as panel costs go down, Inverters are getting more user-friendly, and hence more complex and expensive. inverters alone run from $5000 to $8000 these days.
Recent grid solar installations are far more efficient and cost-effective than their counterparts from five years ago. I'd say that suggests all this research is going somewhere. What, you thought that each of these announcements about laboratory successes would instantly result in a new product on the shelf of your local Wal-Mart?
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The progress report from March 2010, available at http://gcep.stanford.edu/research/factsheets/petesolor_results.html, provides a more detailed and understandable summary of what they are doing
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Even if the tech gets to a point where Joe-Bob can buy a 5,000 watt solar array at Wal-Mart for $999, he won't be able to install it permanently in a safe manner, because you're still dealing with 5,000 watts. It becomes nothing more than a fuel-less generator. Mounting it permanently on his roof, tying it in to his household wiring and setting up a grid-tie net-metering arrangement will still take the work of professionals.
Of course, we may someday get to a point where the process is simplified and routine enough that installation costs might approach something like putting in a tankless water heater, gas lines or satellite dish.
Hi all. I'm one of the researchers on the project. As they say on Reddit, Ask Me Anything. I'll do my best to answer everyone's questions.