5 ms·

40% is not, in fact, 3x, or even 2x, current best efficiency of Si or CdTe panels. And, the important efficiency measure is W/$, where GaAs trails well back. P

by ncmncm 4y ago

40% is not, in fact, 3x, or even 2x, current best efficiency of Si or CdTe panels. And, the important efficiency measure is W/$, where GaAs trails well back. Perovskites may exceed 40% conversion efficiency, and also have good prospects to offer much better W/$. Their endurance has grown encouragingly quickly.

johnday 4y ago
If we are talking about solar installations on land, rather than in the built environment, the W/$ also needs to factor in the cost of the land itself, which is at a premium in many places including across Europe. On that basis there is scope for an increased efficiency to lower the cost delta.
- ncmncm 4y ago
  You have clearly missed the point that siting solar has no need to interfere with other, simultaneous uses of the land.
anonymousiam 4y ago
If you looked at the first link I cited, they claim 47% efficiency is possible. That is more than 3x the efficiency of many Si panels on the market today. Unlike perovskites, which to date have only achieved ~25% efficiency, GaAs cells have been produced with efficiencies approaching 70% (under laser illumination). https://www.ise.fraunhofer.de/en/press-media/press-releases/2021/record-efficiency-68-9-percent-for-gaas-thin-film-photovoltaic-cell.html https://www.ise.fraunhofer.de/en/press-media/press-releases/... W/$ goes down with manufacturing efficiency. Nobody has done large scale manufacturing of multi-junction GaAs cells.
- philipkglass 4y ago
  If you looked at the first link I cited, they claim 47% efficiency is possible. That is more than 3x the efficiency of many Si panels on the market today. Top-end GaAs technology wouldn't compete with bottom-end silicon technology (the below-16% panels that you mention). It would compete with top-end silicon technology, which is already commercially available at module efficiencies above 22%: https://cdn.energypal.com/panels/spr-x22-370/energypal-solar-panel-spec-datasheet-sunpower-x-series-x22-370w-spr-x22-370.pdf https://cdn.energypal.com/panels/spr-x22-370/energypal-solar... Note that the upper cell efficiency limit for any single material under incident terrestrial sunlight is about 33.5%: https://www.energy.gov/eere/solar/multijunction-iii-v-photovoltaics-research https://www.energy.gov/eere/solar/multijunction-iii-v-photov... GaAs cells reported to operate above this limit are part of multi-junction cells and/or incorporate optical concentration systems to focus sunlight to higher intensities. The experimental record-holder of 47.1% uses a multi-junction cell plus optical concentration. Optical concentration only works with direct normal illumination; light that is scattered through haze or clouds can't be focused, so optical concentration systems are a good match only for sunny areas that have clear skies year-round. That said, the National Renewable Energy Laboratory is researching ways to make GaAs cells at lower cost: https://www.nrel.gov/news/video/building-low-cost-high-efficiency-solar-cells-text.html https://www.nrel.gov/news/video/building-low-cost-high-effic... At low enough cost, GaAs modules could compete directly with premium silicon solar modules. They could conceivably be lighter as well as more efficient than silicon, since thinner layers of GaAs are needed than silicon layers, which in turn reduces the required module rigidity, thickness, and weight.
  - anonymousiam 4y ago
    The fine article was about the efficiency of cells vs. their geometric footprint. If the cost of the footprint is considered, smaller GaAs cells might be more economical than the larger (but cheaper) Si cells. Also, conentrators might be nothing more than a few mirrored/angled surfaces at the edge of the cell, which would increase cell illumination independent of cloud cover. It's not rocket science.
  - ncmncm 4y ago
    Gallium is not an abundant element. The cost of large amounts of GaAs in unlikely to come down much.
Schroedingersat 4y ago
I thought single junction was limited to mid 30% somewhere. Are multi junction perovskites cost effective or is a single junction over 40%?
- ncmncm 4y ago
  As with all these high-efficiency things, different layers are tuned to take up different wavelengths. Shortest on top, longer underneath.
  - Schroedingersat 4y ago
    Yes, but is anyone seriously considering multi junction panels for stationary applications? When there is an abundance of free rooftops and parking lots and plenty of low quality rural land for under 20 cents per square metre it doesn't seem to make a lot of sense to pay over double for less than double efficiency.
    - ncmncm 4y ago
      For the case of perovskite cells, adding layers does not seem to multiply the production cost. Certain uses place a premium on areal efficiency, notably aerospace. But anybody who has maxed out their own collection area, whether a roof or reservoir, can get more revenue from using better cells. And, the more of that that is done, the faster their price falls. We may reasonably expect the price of multilayer perovskites to drop below cost of silicon panels. Sooner is better, which is driven by maxed-out demand.
      - Schroedingersat 4y ago
        > For the case of perovskite cells, adding layers does not seem to multiply the production cost. I guess this makes sense given the hard bit is the substrate. This would be good for everyone as second hand silicon cells for 10-30c/W will open up a bunch of new uses.

by ncmncm 4y ago

johnday 4y ago

If we are talking about solar installations on land, rather than in the built environment, the W/$ also needs to factor in the cost of the land itself, which is at a premium in many places including across Europe. On that basis there is scope for an increased efficiency to lower the cost delta.

ncmncm 4y ago
You have clearly missed the point that siting solar has no need to interfere with other, simultaneous uses of the land.

anonymousiam 4y ago

If you looked at the first link I cited, they claim 47% efficiency is possible. That is more than 3x the efficiency of many Si panels on the market today. Unlike perovskites, which to date have only achieved ~25% efficiency, GaAs cells have been produced with efficiencies approaching 70% (under laser illumination). https://www.ise.fraunhofer.de/en/press-media/press-releases/2021/record-efficiency-68-9-percent-for-gaas-thin-film-photovoltaic-cell.html https://www.ise.fraunhofer.de/en/press-media/press-releases/... W/$ goes down with manufacturing efficiency. Nobody has done large scale manufacturing of multi-junction GaAs cells.

philipkglass 4y ago
If you looked at the first link I cited, they claim 47% efficiency is possible. That is more than 3x the efficiency of many Si panels on the market today. Top-end GaAs technology wouldn't compete with bottom-end silicon technology (the below-16% panels that you mention). It would compete with top-end silicon technology, which is already commercially available at module efficiencies above 22%: https://cdn.energypal.com/panels/spr-x22-370/energypal-solar-panel-spec-datasheet-sunpower-x-series-x22-370w-spr-x22-370.pdf https://cdn.energypal.com/panels/spr-x22-370/energypal-solar... Note that the upper cell efficiency limit for any single material under incident terrestrial sunlight is about 33.5%: https://www.energy.gov/eere/solar/multijunction-iii-v-photovoltaics-research https://www.energy.gov/eere/solar/multijunction-iii-v-photov... GaAs cells reported to operate above this limit are part of multi-junction cells and/or incorporate optical concentration systems to focus sunlight to higher intensities. The experimental record-holder of 47.1% uses a multi-junction cell plus optical concentration. Optical concentration only works with direct normal illumination; light that is scattered through haze or clouds can't be focused, so optical concentration systems are a good match only for sunny areas that have clear skies year-round. That said, the National Renewable Energy Laboratory is researching ways to make GaAs cells at lower cost: https://www.nrel.gov/news/video/building-low-cost-high-efficiency-solar-cells-text.html https://www.nrel.gov/news/video/building-low-cost-high-effic... At low enough cost, GaAs modules could compete directly with premium silicon solar modules. They could conceivably be lighter as well as more efficient than silicon, since thinner layers of GaAs are needed than silicon layers, which in turn reduces the required module rigidity, thickness, and weight.
- anonymousiam 4y ago
  The fine article was about the efficiency of cells vs. their geometric footprint. If the cost of the footprint is considered, smaller GaAs cells might be more economical than the larger (but cheaper) Si cells. Also, conentrators might be nothing more than a few mirrored/angled surfaces at the edge of the cell, which would increase cell illumination independent of cloud cover. It's not rocket science.
- ncmncm 4y ago
  Gallium is not an abundant element. The cost of large amounts of GaAs in unlikely to come down much.

Schroedingersat 4y ago

I thought single junction was limited to mid 30% somewhere. Are multi junction perovskites cost effective or is a single junction over 40%?

ncmncm 4y ago
As with all these high-efficiency things, different layers are tuned to take up different wavelengths. Shortest on top, longer underneath.
- Schroedingersat 4y ago
  Yes, but is anyone seriously considering multi junction panels for stationary applications? When there is an abundance of free rooftops and parking lots and plenty of low quality rural land for under 20 cents per square metre it doesn't seem to make a lot of sense to pay over double for less than double efficiency.
  - ncmncm 4y ago
    For the case of perovskite cells, adding layers does not seem to multiply the production cost. Certain uses place a premium on areal efficiency, notably aerospace. But anybody who has maxed out their own collection area, whether a roof or reservoir, can get more revenue from using better cells. And, the more of that that is done, the faster their price falls. We may reasonably expect the price of multilayer perovskites to drop below cost of silicon panels. Sooner is better, which is driven by maxed-out demand.
    - Schroedingersat 4y ago
      > For the case of perovskite cells, adding layers does not seem to multiply the production cost. I guess this makes sense given the hard bit is the substrate. This would be good for everyone as second hand silicon cells for 10-30c/W will open up a bunch of new uses.