I'm no engineer, but if I was making a vessel with extending sails, solar panels, mast, antennae, etc. I would make them widest close to the core. But Juno's solar panels narrow toward the core as shown in the image below and get wider further from core. Why is this?
At first I thought it had something to do with reinforcing the wings, but they cannot support themselves in gravity anyway. Looking into it further I found this:
"The layout and size of the panels are oriented in that nice symmetrical hexagon so the instruments will have an unconstrained field of view," Gehling said.
Not really familiar with the vehicle or the specifics of how it was mated to its launch vehicle but my first reaction would be that it probably is driven by either a packing constraint or possibly is related to the specifics of the deployment mechanism or sequence.