Batteries always die at the worst possible time. Whether it’s your phone when you need to book a 3am Uber, your headphones as you board a 12-hour flight, or your camcorder just as your sprog takes their first steps. What? Some people still have camcorders, all right? But if you’re lost in the wilderness (or somewhere scary like Andheri) and there’s not enough juice left in your Casio G-Shock Rangeman GPR B-1000 (US$800 or ₹50992 approximately) to power the GPS navigation, you can use energy from the sun to keep the sat-nav going for an extra hour, which should hopefully be just enough to get you back to safety. Phew.