Originally Posted by
mishasibirsk
I won't claim the engineering knowledge that Altaskier apparently does. Nor do I suppose that there currently exists a ready-made option for fitting commercial, passenger aircraft with solar panels. But my nose registers, at a sensitivity of 1 ppm, any whiff of snowing with figures, AKA BS by numbers. So, 1) Batteries? No-one would suggest solar as anything but an auxiliary power source for large aircraft; the power produced would be immediately fed in to replace the usage of some liquid fuel - no storage (incidentally, when parked, the plane could be plugged in and supplying power to the airport), 2) solar panels designed to cover roofs and solar arrays would, yes, be too heavy, too inflexible, too destructive of laminar air flow, to be fitted on an aircraft's wings... but who says only those kinds of panels could be used. Why not design panels for aircraft wings? As it is, there is already a wide variety of panels in production, and much more in the lab. There is talk of spray-on panels. It's fair enough to say there is nothing good to go right now. To say there never can be is drawing a long bow. 3) 1.4 watts/m2...Was that the figure? All I know is, I can't imagine that insolation at 10,000+metres isn't going to be far higher than at any terrestrial location, and the capacity factor should be higher - there is still the limitation by angle of incidence, but almost none of the usual diminution due to the sun slanting through a great slab of morning and evening atmosphere.
BTW, why only the wings? The fuselage is not tiny, and would present less of a flexibility problem.
I'm glad you have such a sensitive nose, but you might try some numbers too.
1. "All I know is, I can't imagine that insolation at 10,000+metres isn't going to be far higher than at any terrestrial location" -
1.4 kW/square meter is the insolation rate ABOVE earth's atmosphere as noted in my original reply, and 1 kW/sq.m. in sunny desert areas, so in spite of your imagination the insolation estimates in my numbers are reasonable estimates. Furthermore, factors of 40% (i.e., assuming absolutely no atmospheric absorption at 10,000 meters) don't change the main point.
2. The fuselage of a 737 has a top-viewable area of about 100 square meters (3.5 m width, 31 m length). So yes, you could in principle double the energy gain to 4 kg/hour of jet fuel equivalent. And again, I argue that it doesn't change the main point.
3. Spray-on solar panels presumably refer to organic photovoltaics, which have significantly lower conversion efficiency at present (the red dots at the lower right of
this chart).
If you think there is "BS by numbers" in my reply, please provide quantitative, citable counter-arguments rather than sniffing your nose. I am in fact quite supportive of solar photovoltaics on rooftops where they are already nearing economic break-even, but we should be honest about its appropriateness for transportation applications (especially aircraft).