SBSP--specific power

The specific power in kg/kW for a power satellite is a critical number for evaluating the economics of this method of power production.

Multiplied by the cost per kg for the lift to GEO it is the transportation cost of building power satellites.

In order for SBSP to capture market, the cost for an installed kW needs to be around $1600/kW. If the allowed transport cost is $500, then the product of kg/kW and dollars per kg can't exceed $500.

It appears very difficult to reduce the cost to GEO below $100/kg. The requires the specific power to be close to 5kg/kW.

Because of the way SBSP is measured (output of the rectenna) and the 50% transmission loss, the specific power before transmission needs to be 2.5 kg/kW. Allowing 1 part in 5 (20%) for the microwave transmitter and transmitting antenna leaves only 2 kg/kW for the power production system.

There are PV and thermal cycle proposals. Most work has been with PV, which leads to long and heavy conductors to get the power to the transmitter. Given that a 60% efficient thermal system takes 1/4th of the area of a PV system, the analysis will below will be on thermal systems.