And that makes solar power satellites more feasible, especially with the BFR. Musk has expressed skepticism, famously asking "what's the conversion rate?" The

And that makes solar power satellites more feasible, especially with the BFR. Musk has expressed skepticism, famously asking "what's the conversion rate?" The answer is that microwave transmission is 40% efficient with today's technology. This isn't bad considering that average daily sunlight in geosynch is five times higher than on the ground,[1] and you don't need much storage or backup. The early SPS designs were hugely expensive monolithic beasts, but current designs use lots of identical parts (of several varieties) that self-assemble in orbit, so you get economies of scale with factory production. A year ago I read the book The Case for Space Solar Power [2], which broke down the costs in detail. With pre-SpaceX launch costs they got 15 cents/kWh, including manufacturing and ground stations. I plugged in the BFR cost Musk was claiming (I think I used $50/lb) and got about 4 cents/kWh. [1] https://en.wikipedia.org/wiki/Solar_irradiance#Irradiance_on_Earth's_surface https://en.wikipedia.org/wiki/Solar_irradiance#Irradiance_on... [2] https://www.amazon.com/Case-Space-Solar-Power-ebook/dp/B00HNZ0Z96 https://www.amazon.com/Case-Space-Solar-Power-ebook/dp/B00HN...