• Echo Dot@feddit.uk
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    20 hours ago

    It depends how you’re defining it. 95% of all wavelengths that hit it being converted is impossible, because solar panels only work within certain spectral ranges, but it’s theoretically possible, although technically difficult, to have 95% of all relevant wavelength photons converted into electricity.

    • davetortoise@reddthat.com
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      17 hours ago

      For a p-n junction based cell, the theoretical maximum efficiency is about 33%.

      You can game this a bit using tandem cells with layers of varying bandgaps, but even as the number of layers approaches infinity the theoretical maximum only increases to about 68%. They’re also not hugely practical or cheap, obviously, and in practice they barely reach above the regular limit of 33% due to engineering constraints. There are some other ways of trying to get around it, but I don’t know of any that can approach 95% efficiency.

      Worth noting that this is staggeringly high efficiency in comparison to most other energy sources, given that at the end of the day all of them ultimately come from sunlight.

        • davetortoise@reddthat.com
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          16 hours ago

          Ooh cool I hadn’t heard of them! My understanding from the wiki page though is that the 90% efficiency refers to energy transfer efficiency within the microwave range, rather than the conversion rate from sunlight which is theorised to be about 70%. The stuff about generating power in space using solar cells then transferring it back to earth sounds awesome, though possibly a bit impractical compared to regular solar farms.

          • CheeseNoodle@lemmy.world
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            16 hours ago

            Technically you could use them on the ground too, they just make a convenient method to build a recieving station for microwave beaming, so potentially if we ever get them working in optical ranges its just a much better solar pannel.