Warning … Warning … The following is unencumbered with a reality check – or even research. You have been warned.
My problem is that I would like to power a Raspberry Pi (5V about 0.8A) during a balloon flight (4 hrs) using an 11.1V LiPo battery maybe 300 to 800 mAhr, supplemented with a 15W array, instead of using a 4000 mAhr battery. I try to size things to run 4 hrs. And no, I don’t know if this actually saves weight. However it would be cool to accomplish.