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New Solar Cell Sets World Efficiency Record
asoduk writes to tell us that a new world record has been set for the most efficient photovoltaic device. Topping the scale at 40.8% efficiency, the new solar cell differs significantly from the previous record holder. "Instead of using a germanium wafer as the bottom junction of the device, the new design uses compositions of gallium indium phosphide and gallium indium arsenide to split the solar spectrum into three equal parts that are absorbed by each of the cell's three junctions for higher potential efficiencies. This is accomplished by growing the solar cell on a gallium arsenide wafer, flipping it over, then removing the wafer. The resulting device is extremely thin and light and represents a new class of solar cells with advantages in performance, design, operation and cost."
At 40%, you're talking about 400W when in direct sunlight. With eight hours of sunlight per day the average house needs less than four square metres. Now, of course, you aren't going to be using the most power at the times when these are generating, but it can definitely put a significant dent in your electricity bills.
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Was taking forever to load, so here's the article:
Scientists at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) have set a world record in solar cell efficiency with a photovoltaic device that converts 40.8 percent of the light that hits it into electricity. This is the highest confirmed efficiency of any photovoltaic device to date.
The inverted metamorphic triple-junction solar cell was designed, fabricated and independently measured at NREL. The 40.8 percent efficiency was measured under concentrated light of 326 suns. One sun is about the amount of light that typically hits Earth on a sunny day. The new cell is a natural candidate for the space satellite market and for terrestrial concentrated photovoltaic arrays, which use lenses or mirrors to focus sunlight onto the solar cells.
The new solar cell differs significantly from the previous record holder - also based on a NREL design. Instead of using a germanium wafer as the bottom junction of the device, the new design uses compositions of gallium indium phosphide and gallium indium arsenide to split the solar spectrum into three equal parts that are absorbed by each of the cell's three junctions for higher potential efficiencies. This is accomplished by growing the solar cell on a gallium arsenide wafer, flipping it over, then removing the wafer. The resulting device is extremely thin and light and represents a new class of solar cells with advantages in performance, design, operation and cost.
NREL's Mark Wanlass invented the original inverted cell, which recently won a R&D 100 award. His design was modified by a team led by John Geisz that further optimized the junction energies by making the middle junction metamorphic as well as the bottom junction. Metamorphic junctions are lattice mismatched - their atoms don't line up. The material properties of the mismatched semiconductors allows for greater potential conversion of sunlight.
NREL is the U.S. Department of Energy's primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for DOE by Midwest Research Institute and Battelle.
We will have solar energy as soon as the utility companies solve one technical problem -- how to run a sunbeam through a meter.
They say a little knowledge is a dangerous thing, but it's not one half so bad as a lot of ignorance. - Terry Pratchett
The new cell produces enough electricity that if you covered a football field with them, it would be enough power to run an Olympic swimming pool full of hard drives. The additional electricity these cell provide compared to the previous record holder would allow you to copy several libraries-of-congress per second faster to your pool full of drives.
Hope this helps.
While I agree that these types of announcements are overblown (they are talking about high-concentration PV here, which is not a good idea to put on roofs at all for structural reasons, and it only responds to about 80% of the available irradiance anyway due to being limited to beam radiation), the ROI is highly dependent on the economic conditions of the owner. Solar can payback fast if you are a large electricity user in the upper tiers of pricing even without incentives, and with incentives the banks are loving it today in many locations. If you are off-grid in a sensitive environment, you may have little alternative... what is the ROI on that? If you are living in a tiny home in a mild climate with no air conditioning, your ROI could indeed be prohibitive... but blanket statements about ROI are NOT "insightful", moderators.
How much do they cost and when can I get some?
If the goal here is to move away fom the consumption of materials in short supply, solar cells based on gallium and indium aren't going to help. We had a world-wide gallium shortage at the turn of the millenium, and that only receeded because demand slacked off some. There is currently a shortage of indium that started in 2007.
Both of these elements are hard to come by because they are not just rare, but sparsely distributed. Indium is produced from lead, zinc, and tin production waste, and I think gallium mostly from aluminum production waste. I'm sure supply will increase over time, but we can't quickly ramp up production of either element by "mining more".
Niether of these elements would remain economical if there were a sharp spike in demand.
Socialism: a lie told by totalitarians and believed by fools.
I don't see the problem. All we need to do is develop a cheap, efficient form of fusion to create the exotic elements we need so that we can produce these solar cells to provide a new source of cheap, efficient energy.