Can you clarify the 70% efficiency claim in the article? I assume this is 70% efficiency of DC conversion of received power, and not any sort of end-to-end metric?
Reporters sometimes tend to pretend they are novelist and get many details wrong (to put it mildly)
70% efficiency is the current state of the art limit for solid state based Tx. we loose close to 0% in the atmosphere and our Rx is well beyond 90% efficient.
Wow! Please do set up an aggressive schedule to build the first space solar station. The Earth urgently needs its Dyson swarm already. With such distances under test you are very close to the goal.
I bet Musk will be your best friend if you brief him with such project ;)