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-

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.