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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."
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.