They're called solar panels for a reason: they need the sun in order to generate electricity. Whether we're talking about pocket-sized, portable solar chargers or massive rooftop arrays, direct sunlight is the must-have ingredient on which all other elements of solar-energy production depends.
You might think that simply placing solar panels on a rooftop or balcony free from shade would be enough. Except there's that small matter of Earth rotating on its axis. So throughout the day, the sun moves across the sky, cutting into the efficiency of fixed panels. But what if the panels could automatically change their position to follow the sun and enjoy an uninterrupted flow of direct sunlight? Two electrical engineering students at Cornell are currently testing just such a technology, and it looks promising.
As this review points out, HelioWatcher's design is simple and effective: "The base is mounted like a Lazy Susan, able to pivot on the horizontal plane. The bottom edge of the solar panel is mounted with two door hinges, with a motorized screw jack used to raise and lower it." Using a GPS module and magnetometer, the HelioWatcher allows the user to place the system anywhere in the world without any calibration. The HelioWatcher then calculates what the sun’s current location is and orients the panel to the appropriate angle. It also utilizes a quadrature of light-detecting diodes to correct for short-term light obstruction, such as clouds or shade.
This system is a vast improvement over other solar tracking systems that adjust position based on either a predetermined algorithm or light detection. Instead HelioWatcher combines elements of both technologies to leverage the guaranteed accuracy of a geospatial algorithm while also correcting for local or short-term changes, such as cloud cover or shade. Here's a video, prepared by the two students, that explains the system: