Things are far more compex than you are suggesting.  The tradeoffs for spead work out largely because you can increase altitude which is very useful.<p>I accept that Solar does not work to supplement  the onboard generator used for electrical power on jets due to weight and night time flights. At the same time solar is ~1% the fuel cost for that amount of power for 20 years.  They say they can scale this up 50x and carry 50 people. IMO, it would be better to build cargo only craft in that size range as this is far to slow outside of sight seeing in VFR.<p>Not to mention wind. That said if you can say double the solar power and add significant altitude and speed that&#x27;s much more viable.  I am assuming this is significantly worse than the best possible solar aircraft we could build in say 30 years.