This technique is being used and is a huge business in the Philippines. This is really resourceful for those that choose to stay well hidden in the
SHTF scenario, and have no natural light that can enter the area in which you will need it the most.
This can also eliminate the use of candles and battery powered flashlights, which will eventually go out, or run out.
BTW, I can also see how this can be used in a home for light if you have a one floor home, or can get someone the install one on your roof, and can
use it ti light your home during the day. This is also very good for those that live in rural areas, and mobile homes.
CCTV-9 report: Solar bottle lights in the Philippines
Peace, NRE.