US Navy Tinkering With Transmitting Solar Power From Space

The U.S. Navy hopes to beam solar power from space using a massive array of solar panels assembled in orbit by a team of robots.
The U.S. Naval Research Laboratory (NRL) says it will seek to patent a variation of an innovative “sandwich” solar module, which is capable of capturing solar energy, converting it to direct current and transmitting it back to earth as a radio or microwave frequency. 
The NRL says by launching enough of these modules into space to form one gigantic solar panel, it could provide enough energy to power a city. 
While the concept may seem a little insane to some, but Dr. Paul Jaffe, a spacecraft engineer at NRL, says it’s “Hard to tell if it’s nuts until you’ve actually tried.” 
Dr. Jaffe has built two sandwich-type solar modules. On the front of each is a photovoltaic panel that collects solar energy, then a layer of electronics in the middle converts that direct current to a radio signal which is beamed away via an antenna mounted on rear of the module. 
Jaffe and his team built a vacuum chamber – the first of its kind – in order to simulate the harsh conditions of space while testing their modules. They used a novel approach to solving the thermal problem by using the ‘step’ module”, which opens the sandwich up like a zig-zag. Jaffe found this not only increased the module’s efficiency, but also allowed it to deal with greater concentrations of sunlight without frying. 
He also made improvements to the complex antenna system. “Antennas look simple,” Jaffe says, “you would never believe all of the calculations and analysis.”
According to the NRL, the modules would have to be launched separately, and then assembled in space by robots. That research is already being advanced by NRL’s Space Robotics Group. 
The NRL’s vision for space-based solar power is driven primarily by the U.S. military’s vast energy requirements. If viable, its goal is to build a kilometre-wide solar array that could theoretically beam power directly to a receiver anywhere on the planet.