Cost is probably what killed that project, but it's not entirely stupid, although it would certainly be better with a foldable panel at the back of the screen t

Cost is probably what killed that project, but it's not entirely stupid, although it would certainly be better with a foldable panel at the back of the screen that can be positioned optimally. A 30x20cm laptop could get at best 12-10W of sun power with a solar panel on its surface. You could build a useful laptop with the same spec as a smartphone with a standard 4000mA battery and need about a charge a day in normal use. Since the exposure of your laptop to the sun would be suboptimal, you may only get 4W for say 5h a day, which seems fairly reasonable and is enough to recharge the battery every day. Even on bad days, you would probably be able to use your laptop half of the time, which could still be a few hours and enough to make a difference to someone with otherwise no access to technology.