What better opportunity than Earth Day to point out another way that photonics plays a role in improving the planet? Awareness of the importance of taking care of the earth is becoming more widespread, and most importantly, not just in the affluent countries of the world. In fact, the developing nations are where some of the most innovative efforts are taking place. We've highlighted micro-solar projects in Africa and elsewhere, and the previous post about the LEDs being used to protect livestock from lions shows another brilliant but simple use of photonics. Here's one that combines solar energy and an expanding communications infrastructure in India. AirJaldi Networks, a company that provides solar-powered Wi-Fi for the rural masses, was plagued by the difficulty of maintaining power to its mobile phone towers in remote areas, especially during the monsoon season. Battery backups were expensive and frequently necessary. As GreenTech Solar reports : Here’s how it works: