It does look like the power requirements of a dedicated simplified eReader could someday
get that low. But keep in mind:
1 Square Inch = 0.00064516 Square Meters
The max solar energy reaching the surface of the earth is ~1kw (1,361w)per square Meter.
My 5" eReader = 12 square inches = 0.00774192 square Meters
0.00774192 x 1000W = 7.74192W
About 8W, sounds good right? But, the drop off from perfect collection conditions is
steep and no solar panel tech is 100% efficient. The PV sites will claim 10 or 11 Watts
per square foot of an array. (That is the most reputable of them.)
http://en.wikipedia.org/wiki/Solar_cell#Efficiency
Notice that the best cells, outside the lab, are 35% efficient or less.
.35 x 8W = 2.8W, if the panel could intercept the max total solar.
My battery pack holds a little over 11wh so if we said it was 12wh and the panel could
provide 3W then four hours in perfect sun should charge the device.
So, maybe.
Luck;
Ken