Additional details of the "SPS-ALPHA Mk-II" will be presented in the second edition of a Mankin book. The book is planned for release in 2018.
* using thin reflectors
* using robotic arms for assembly
* using lower cost launch systems
* improving the module design
* improving the reflector designs to make the system last longer which reduces operating costs
Getting to less than 2 cents per kwh would make it cheaper than coal and natural gas power.
High re-use for first stages for the Falcon 9 block 5 would get its cost to about $1500 per kilogram to low earth orbit.
High re-use for first stages for the Falcon Heavy would get its cost to about $1000 per kilogram to low earth orbit.