I know a lot about solar power and trust me, space solar power is not a good option.
Elon Musk, Aug 3, 2006

When Caltech looked at the sailboat that lost the America’s Cup, they found that it had less drag being dragged backwards than forwards.

The case for beaming solar power to Earth is bad. So bad that it actually works better to beam from Earth to space.

A coal plant costs about $0.75/watt peak capacity ($1B for a 750MW plant), plus $0.07/Watt Year (Wy) in coal to run all the time. Space solar costs about $202.5/watt. Let’s make the heroic assumption that we can build and launch 100,000 kg satellites. If we need a team of 12 people earning $15 an hour to take care of the satellite ground operations ongoing, then we can keep the $360k in wages to $0.07/Wy.

What about $100/kg launch costs (1% of now) $0.025 manufacturing costs (1% of now) where we can expect the floor of orbital transport prices to be for decades because that is 10% of the price of the existing suborbital flights that have $10 million in deposits. Surely at $10,000 to orbit, there would be enough takers to sell out capacity until a major construction push on orbital launch capacity was made. At $2.025/watt, and 10% interest, coal prices would still need to triple to make the math work. That is, we need a factor of 300 through some combination of lower launch and manufacturing costs, watts/kg, coal taxes or emissions credits.

On the other hand, we get about 8% energy efficiency sending power from the Earth to the Moon. That translates to $1.80/Wy for Earth power on the Moon vs. $20.32/Wy for solar (at the pole!). Add $175/w for lasers and $313/w for mirrors (or about $100 million for four 2.5 meter mirrors and 8 2.4 kW lasers), then we can increase comm. sat. launch payload by 50% to save a good fraction of $1 billion per year in launch costs and billions more by having longer lived satellites and lower insurance costs. In the mean time, we can run satellites whose batteries have gone down or whose solar panels never fully deployed for longer and with more function ($500 million/year estimated value).

So shoot the energy into space to colonize space and the Moon. When the prices for space manufacturing come down to Earth, then we can talk about space solar.