so yeah, again you didn't read the article, if you had you would have come across things like...
>> One tiny little question, the light pressure on this giant solar array, how will it be compensated? You know, the same light pressure that's supposed to drive solar sails to other stars? So, will we 3D print a reaction system to keep the panel oriented? Hmm? Oh OK, we'll just add some ion thrusters every few meters... Oh, how are you going to refuel it? More 3D printers?
"TFA" - I mean, c'mon there's a whole paragraph with link to further reading, here's a little snippit from the article.
Using a technique called gravity gradient stabilization, the bus would act as a counterweight to the huge panel.