Answer:
Solar panels area group of 36 solar cells arranged on a board to produce a level of usable power. Each cell produces just under 1 vdc. Ganging these up into a set of 36 allows the system to produce around 12 to 15 vdc. This allows the charging of a car battery.
They do allow for power in very remote applications and are great for campers and areas were power is not always available. They are much "greener" then portable generators.