You’ve probably seen calculators with solar cells — devices that never need batteries and in some cases, don’t even have an off button. As long as there’s enough light, they seem to work forever. You may also have seen larger solar panels, perhaps on emergency road signs, call boxes, buoys and even in parking lots to power the lights.
Although these larger panels aren’t as common as solar-powered calculators, they’re out there and not that hard to spot if you know where to look. In fact, photovoltaics — which were once used almost exclusively in space, powering satellites’ electrical systems as far back as 1958 — are being used more and more in less exotic ways. The technology continues to pop up in new devices all the time, from sunglasses to electric vehicle charging stations.