The true objective of its service to mankind is realized only when a(ny) technology becomes useful and affordable for those who appropriately need it. Here is one such happy, bright, instance.

Solar water bottle light bulbs to lit homes. Take a plain plastic water bottle, fill it up with clean water, add bleach to prevent formation of algae, fix it in a hole on the roof. You get about 55 Watts of refracted solar energy in day time, to lit your house.