Japan is eyeing outer space as a great piece of real estate for building solar power plants.

Mitsubishi Electric Corp., IHI Corp. and 14 other companies plan to spend 2 trillion yen ($21 billion) to explore the idea of building a 1-gigawatt solar power farm in space. The power plant would turn electricity into microwave radiation and beam it down to Earth.

The concept has been around for decades. Other companies and government research institutions have been researching the idea for some time. As you can imagine, costs and technical challenges are the stumbling blocks (here is a website by the Georgia Institute of Technology on space solar).

Pacific Gas and Electric in California has gone as far as to sign an agreement to buy space solar power. The deal, announced in April this year, would entitle the utility to get electricity from a 200-megawatt project by 2016. Solaren Corp. in Manhattan Beach, Calif., is the developer.

Satellites outfitted with solar power generating equipment would be launched, Solaren executives have said. The electricity would be turned into microwave and beamed to a station in Fresno County, where the radiation would be converted back to electricity.

The Japanese consortium plans to spend four years on developing the technical knowhow to make space solar power possible. The plan is to build a 1-gigawatt station that comes with four square kilometers of solar panels, reported Bloomberg.

Building a solar power farm in space has one key advantage: it won't be subjected to weather conditions that affect the performance of terrestrial solar power plants.

There already are satellites outfitted with and powered by solar panels. The International Space Station has them. SpectroLab, a subsidiary of Boeing, has been making solar cells for satellites.

But to launch a large-scale project into space and to send the electricity to a receiving station on Earth will prove to be very tricky.