The cheap, solar-powered bulbs are actually just clear plastic soda bottles filled with a mixture of purified water and chlorine or bleach which is commonly used in household cleaning products.
Each bottle is then inserted halfway into a hole made on the roof of a house, and sealant is applied to prevent leaks and the end result gives the impression of a small, plastic chimney.
The bulb gives off light equivalent to a 55-watt electric lamp as the water inside the bottle refracts sunlight and other exterior light.
Impractical for Canada (snow? ice? polar bears?), but an interesting idea for a cheap lightbulb during the day in such homes.