Remember those little black glass panels on those calculators that never needed batteries? They were usually marked “solar-powered.” And, they were. Those little panels are actually called “photovoltaic cells.” They take “solar radiation,” or sunlight, and convert it into energy, protected by that glass panel. Usually, this energy created by the photovoltaic effect is direct current energy—DC—the kind of energy provided by batteries. That is why it can be used to power that calculator on your desk.
The first usage of this technology was actually more momentous than you would think. Engineers needed a way to power satellites in space after their batteries gave out. You cannot run a power cord all that way, and batteries, while a temporary fix, would need replacing. (Houston, we have a problem—we’re out of AA’s.) Eventually, it was thought of to harness the big flaming ball of energy in the sky.
Photovoltaic cells work by exposing electrical diodes to sunlight, causing a reaction that jerks out free electrons. This creates a voltage by making an imbalance in the electron charge. Then, the diode can be hooked up to channel that energy into some kind of harness or storage, like a rechargeable battery.
As technology improves, researchers have been working harder to capture more and more of the sun’s energy to use as electricity. It is, for humankind’s intents and purposes, the ultimate infinitely renewable resource. This was realized in Japan in 1966, when the Ogami Lighthouse became fully powered by photovoltaic arrays. (Arrays are large groups of photovoltaic cells wired together.) Eventually, solar panels started becoming a possible alternatives to provide basic energy to locations that were either difficult to run power lines to or were temporary in nature. As technology improves to the point that it becomes cheaper to manufacture, photovoltaic cells have also been used to augment existing electricity supplies. This is seen more in Europe than in America at this point in time. Spain and Germany, in particular, have high solar goals for the installation of solar energy. In fact, Germany has the most number of installed photovoltaic cells in the world. According to the NPD group, over 90% of solar photovoltaic installations are connected to the power-grid in Germany.