I don't understand. If you owned a solar calculator you'd have to pay somebody because you made power ? Huh ? We've discussed before on HN the fact that the "Lets own everything" capitalists apparently didn't realise they needed to own the Sun and Wind (modulo Simpsons cartoon) but I guess maybe yours do? How much do you pay for a sunny day, on average, and if you won't pay do you get clouds or what ?