Solar Power on a Rainy Day

Solar power has achieved continuous improvement in efficiency. The demand is strong as consumer and business interest grows. I would love to implement Elon Musk’s vision at my summer home in Pennsylvania. The vision would include Tesla roof shingles which look like regular shingles but which contain solar cells. they are now available for sale. The second part of the vision is the Tesla Powerwall, a 4 foot by 3 foot by 6 inch battery or two in the garage or on the back terrace. Also available for sale. The sun would produce electricity to power the house and any left over would go to the batteries. If there is a power failure or if the sun is not shining, the battery provides limited power for a limited time. All this is controlled by setting various parameters on a smartphone app. The final part of the vision, of course, is to have a Tesla car plugged into the house and be powered by the sun.

The one catch is where the summer home is located there are a lot of trees. Tesla did an analysis using High Definition satellite imagery and concluded there would be a 20% shortfall of the needed energy for the house produced by the roof. Not enough sun, whether caused by too many trees or too many cloudy days, is a major limitation for the solar power vision. Shingles with solar cells built in are getting more efficient and may soon be adequate for a majority of homes. However, what to do about rainy days and cloudy skies? The Powerwalls can cover part of the problem but not entirely.

The answer may be sending sunshine harvested by a satellite down to Earth. Science fiction writer Isaac Asimov had a vision of space solar power in the early 1940s. Now, 75+ years later, his vision may become a reality. A Naval Research Lab has done a proof of concept where a laser beam was able to transmit 400 watts of power, enough for several small household appliances, across thousands of feet of air. The Navy believes this could lead to sending power to drones during flight.

A series of technological breakthroughs and a new government research program suggest Asimov’s vision may be closer to reality than previously thought. The basic idea is a giant satellite in orbit would collect energy from the sun and convert it to microwaves or laser beams and then transmit them to Earth where the microwaves or laser beams would be converted into electricity. Because the sun never sets in space, a space solar power system could supply renewable power to anywhere on Earth, day or night, rain or shine.

Space solar power has been one of those 30 year out predictions which kept moving further out. But, things are changing. NASA and the Defense Department have gotten behind the idea. In October, the Air Force Research Lab announced a $100 million program to develop hardware for a solar power satellite. The time is right. The military would like to be able to electrify forward operating bases rain or shine. California wildfires have forced PG&E to kill power for thousands of residents on multiple occasions. Solar space energy could provide renewable energy through the clouds and smoke. 

Naval Research Lab electronics engineer Paul Jaffe has been leading the charge on this exciting opportunity. He nicely summarized the geopolitical implications when he was quoted in Wired saying, “With GPS, we sort of take it for granted that no matter where we are on this planet, we can get precise navigation information. If the same thing could be done for energy, it would be revolutionary.”

Earlier this year China announced its intention to become the first country to build a solar power station in space. Japan has considered space solar power a national priority for more than a decade. Now that the U.S. military has gotten behind the solar space power idea and put funding in place, the U.S. may pull ahead. My house in PA vision is going nowhere, but as a country, we may be getting close to a solar farm in the solar system.

Source: How to Get Solar Power on a Rainy Day? Beam It From Space | WIRED