It's the dilemma of the modern car owner. You go on vacation and your GPS-equipped, fully automated car goes dead in the meantime because all the gadgets have drained the battery.
To this end, Canada's ICP Solar is hawking the Sunsei, a dashboard solar panel that plugs into the car lighter or can clamp onto the battery. Plug it in and it will deliver 135 milliamps to the battery, enough to keep it going. The company sells thousands of these to Volkswagen, which puts them in Beetles shipped from Mexico. (Sometimes the dealer gives them to buyers; sometimes, they keep them and sell them later on eBay.)
Unlike some portable chargers, the Sunsei can collect energy from the sun through a windshield. That's because it is made of amorphous silicon and can absorb energy from the blue end of the light spectrum. Blue penetrates windshields, which block red light.
Solar chargers fit fairly well with cars because owners generally don't need a rapid blast of electricity. That's why cell phone chargers don't work well. ICP Solar CEO Sass Peress once did try out a solar phone charger on a plane trip, holding it up to the window. "What other fool is going to do this?" he recalled thinking. ICP canceled the product line.
ICP also sells industrial strength chargers for Winnebagos.