Posted on 09/16/2009 8:17:13 AM PDT by canuck_conservative
Here's a seemingly simple solar power fact*: the sun bathes Earth with enough energy in one hour (4.3 x 1020 joules) to more than fill all of humanity's present energy use in a year (4.1 x 1020 joules). So how to convert it? In the world of solar energy harvesting, there's a constant battle between cost and efficiency. On the one hand, complex and expensive triple-junction photovoltaic cells can turn more than 40 percent of the (specially concentrated) sunlight that falls on them into electricity. On the other, cheap, plastic solar cells under development convert less than 5 percent.
In between, ubiquitous photovoltaicsthe multicrystalline silicon solar panels cropping up on rooftops across the country and, indeed, the worldstruggle to balance the need for (relatively) easy manufacturing and low cost with technology to get the most electrons for your solar buck.
Yesterday, Spectrolab announced that its newest triple-junction solar cells had achieved the world record in efficiency, converting 41.6 percent of specially concentrated sunlight into electricity. All told, a tiny cell just 0.3174 square centimeters turned the sunlight equivalent of nearly 364 suns into 4.805 watts. That kind of efficiency is why 60 percent of satellites in orbit today bear earlier iterations of the technology; that's a total of roughly 640 kilowatts of Spectrolab cells circling Earth.
Those cells cost 40 cents per watt, according to the manufacturerif you happen to have the sunlight equivalent of 500 suns streaming down while enjoying a temperature of 25 degrees Celsius. In reality, only specialized applications like satellites (and government contractors or agencies like NASA) can afford the technology.
More Earth-bound photovoltaics, like Suntech's Pluto line of multicrystalline cells, which boasts 17.2 percent efficiency converting one sun's light into electricity, or Suniva's ARTisun single silicon crystal cells that can convert 18.5 percent of the sunshine into electricity, cost more than $2 per watt. Installation roughly doubles that price.
Bringing the cost of just the photovoltaic cells down to about $1 per watt is the magic number solar manufacturers are aiming for, figuring that will make them cost-competitive with electricity produced by burning natural gas. Some manufacturers of thin film cells (less efficient but cheaper), such as First Solar, claim to have reached that mark, with efficiencies around 10 percent. Finding a way to further boost the ability to convert sunlight into electricity while also lowering costs to this level would herald the true dawn for solar powersomething anticipated since photovoltaics were discovered.
The above is true for photovolataics, but not solar thermal. For solar thermal is possible to store the energy AS HEAT to continue to generate power at night. With eight hours worth of heat storage capacity, a solar thermal plant can provide all energy needs and match the "day-night" demand cycle exactly, without ANY need for fossil fuel "backup".
Cells down to about $1 per watt. Ok now what is the battery cost to keep the lights on until midnight?
Prorated, but the pro-rating is acceptable:
"Kyocera Solar Panels come with a 20 year warranty on the power production of their panels. Because there are no moving parts, the only wear-and-tear these systems see is from daily sun exposure, year after year. This is factored into the 20-year warranty, which states that by the end of the twelfth year, the panels should still be producing at 90% of their initial capacity, and that by the end of the 20th year, they should still be producing at 80% of their rated power."
Nanosolar, which is already selling cells for $0.99/watt, offers a 25 year warranty.
How well do they hold up in hail?
Importantly, if you want the most bang for your buck from solar energy, you have to use it for *marginal* applications, *passive* effects, and *multiplying* effects. Let me use three examples.
To start with, the bulk of your household energy is inexpensive grid power. It is great for this. However, when you get into periods of “peak demand” (in summer or winter, depending on where you live), you enter the “marginal” zone, where suddenly the price of grid power jumps, because its demand jumps. If you can use solar power just to stay *out* of the marginal zone, you save a bundle, and solar power becomes very efficient.
In the hot desert southwest in summer, a home air conditioner in the heat of the day sucks down energy like a sponge, but for the wrong reason. Say it is 115F out, and you want it to be 76F inside your home. What most people don’t realize is that their a/c doesn’t just cool down the inside of their home, but it has to contend with cooling the crawlspace above their home as well. And crawlspace temperatures can get over 140F, easily.
But a little, solar powered fan, that blows the hot air out of the crawlspace, lowers its temperature to “only” 120F. But this 20 degree difference radically lowers the load on the a/c. So a little solar powered fan can save you a $75-100 a month.
Pretty darn efficient. An excellent “marginal” use for solar power.
As a second example, that of “passive” solar energy, works in just the opposite direction. One of the biggest energy use appliances in a home is the hot water heater. Typically, it has to heat cool city water (say 75F) to perhaps 120F. But just diverting the city water to a “passive” roof solar water heater, just a stainless steel tank painted black, it raises the temperature of city water to maybe 100F or more.
And throughout the warm months this can save a huge amount of money. In winter, a simple bypass valve means that the empty tank doesn’t freeze.
“Multiplying solar power effects” still need a lot of development, but can be anything from a solar still to recover fresh water, to using solar powered water electrolysis to get hydrogen and oxygen, both of which are otherwise expensive, but very useful.
I looked into it a few years ago. Same result: makes no economic sense. Two years ago, a solar salesman admitted to me that it’s only for rich people - even with subsidies.
I’d love to have solar power. I hate being on the grid. But I ain’t rich. So until they solve the economics, I ain’t buying.
Thanks Canuck for the link, I’m starting a class next Monday to become a Certified Photovoltaic Practitioner. At present I’m an unemployed licensed electrician, the only jobs out there right now are from out of state firms looking to parachute here to do business in photovoltaics. Basically they lack the licenses, I lack the experience, though I am ahead of the curb having wired two systems out of the 102 commercial systems installed last year in Massachusetts.
So I think come the Spring of 2010 I’ll be ready to install some systems on my own.
I don’t consider myself a “Green” but I hate seeing all of our nation’s profit going to the Middle East, quite sick of it in fact.
I like to see a huge push to nuclear power, then coal, then renewables, seems pretty sensible to me.
A couple of things folks are overlooking when they consider photovoltaics (vs thermal solar) is that it works quite well in the winter, and it introduces energy into the grid exactly when the demand is peak during the day.
Karnage,
“So until they solve the economics, I aint buying.”
If you look at the post above, you’ll see that a very basic system can reap huge rewards. A attic fan can be installed to a module or two, independent of any other system - no batteries, no grid tie in. The sun shines - the fan keeps your attic cool(er), thus the house, cutting the demand for the AC running all day. Just a couple hundred bucks to install.
Look up some of the stuff that I actually work with
flexotricity for example.
I am not AGAINST any of these. I am merely pointing out that what you claim is not currently factual. it is not based on any thermodynamics nor electrochemistry nor materials science. I am not saying it won’t ever happen. I merely pointed to things that already exist. Why won’t you address those????
Actual the solar thermal plants that exist DO have fossil fuel backup .....your understanding of solar thermal comes from reading a few articles not actual experience
“Ok now what is the battery cost to keep the lights on until midnight?”
No need, most systems today have no batteries - they are grid-tied. If you are not home, or have excess power, it is transferred to the grid and the utility pays you for whatever you generate.
Since peak demand is during the day they come on line just when needed. Soon utilities will not simply be charging customers for power used but when they use it. Likewise if you dump a lot of power into the grid during peak periods you’ll be reimbused at a higher rate than nighttime consumption.
How about this calculation....power cutbacks due to societal dusruptions or disaster...suddenly the calculus changes quickly and you’ll wish you had a few of those panels lying around!
What price independence?
You going to worry about alot more than powering a 20W light bulb if that happens...
Having a lot of small appliances/ low power computers ecetera can be powered with those things especially coupled with a battery storage system. I know of a missionary group that put together a village water pump system which also produces enough power to light and power a small mission health clinic in Burkina Faso using a bank of 12 storage batteries and a couple of your average solar panels...(I don’t remember the square footage just the picture of them which I estimate to be less than 200 square feet of panel.)
One of the other posters on this thread says(post 11 JRandom) he lives to far out for utilities so he needs solar power though he admits his power needs are small.
What my point is, is that having access to a power system like this might make a difference between survival or death...it stands to reason that one might not power a whole house hold full of energy sucking equipment but one might power a radio or small tools or medical devices. And yes being able to power a few light bulbs as opposed to living in the dark with out access to replacement candles makes it so that life doesn’t have to totally suck!
The development of thermal storage is a relatively new addition to solar thermal electric technology, but it has been installed and tested well past the "pilot plant" scale, and full-scale plants incorporating it are being constructed.
And no, I am not involved directly in the technology, but I've studied WAY more than "reading a few articles" over the last thirty years. But then, I doubt that you have any better experience base.
Not true at all. The US has vast surpluses of corn, far more than it uses for food internally. Turning part of it into ethanol makes good sense.
Actually I do but that is neither here nor there. I am not saying that this isn’t going to help or isn’t a worthy effort to keep exploring and working on. To the contrary I believe that we should be pursuing all sorts of different technologies. Right now the max output of any of the installed CSPs is 350 MW. That is a nice sized plant. It is in Mohave where there is lots of land and lots of sun.
A lot of the smaller plants help in areas where there is no other infrastructure. That’’s not a bad thing. I was addressing my remarks to the Canadian ( and Americans) who think that this is the be all and end all. There are problems that must be overcome with the technology but I believe that is doable.
There are many ongoing efforts to research and develop many new ideas. There is less effort to develop things such as coal ( since the current administration wants to close basically all coal down) and nuclear which also give us independence from the Middle East. Europe learned this long ago.
http://www.solarelectricsupply.com/systems/grid-tie/discount-gridtie.html
They are rather expensive but the most expensive piece is not the panels. It is the controls and the inverter. It does pay off after a while but the up front cost is prohibitive - for now.
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