I heard a talk from the Space Applications Catapult about this a few months back. It isn't online any more, but some I noted some stats at the time. The station

I heard a talk from the Space Applications Catapult about this a few months back. It isn't online any more, but some I noted some stats at the time. The station would be 1km wide and 4-5000 tonnes in geostationary orbit, producing >2GW. It would beam power down via microwave to a receiving station 3-5km in diameter, so power density would be sufficiently low to not be a danger - "aircraft flying through it would not burst into flames" Projected cost was about equal to HS2 (about $100bn) for the pilot station but with much reduced costs for subsequent deployments.