• Echo Dot@feddit.uk
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      21 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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        19 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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            18 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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              18 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.

      • davetortoise@reddthat.com
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        18 hours ago

        Surprisingly not! I’d have expected photosynthesis to have similar energy efficiency to man-made solar panels, but it’s actually only around 11%. I suppose since leaves have more functions than just energy generation for a plant, it’s not usually an evolutionary imperative to maximise efficiency. There’s probably a bit of variation between different geographic regions, I’d imagine.

        • MonkderVierte@lemmy.zip
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          17 hours ago

          Ah, i meant the chloroplasts only. There’s ongoing research to replicate the high efficiancy, something with a wavelength matching molecular “antenna”. What was it, somewhere over 90%.