One of the presentations at the Space Investment Summit was on Lunar solar power. Solar satellites were also referred to. One presentation noted that if a government agree to buy solar at $0.85/kwh (about a 900% subsidy) that space solar would pay. Great. You can make $50 billion if they give you a $70 billion subsidy. Hand me a glass of ethanol.

My previous best efforts on solar are here, here, and here.

I think there is a fairly simple case against. Grant that space solar is 4x as efficient per kilogram as Earth solar. Ignore the fact that people want more power during the day than at night. Grant that we can take raw silicon and turn it into solar cells with minimal remote human input. Grant that we can beam it. Ignore that if we import solar power in quantity that the price of coal and uranium will drop until they are competitive again as fuels.

Can’t we just set one of the ‘bots that will build the cells loose in an Earth desert? Doesn’t it require the transportation cost to space be on the order of 4 times the manufacturing cost for space solar to be economically effective? Even if we are just talking about the regolith eating robot, don’t we have to get transportation cost down to three times the cost of producing a sand eating robot and letting it loose in the desert? Am I missing something? I think this argument means space solar will never be competitive.