When you mine the panel it appears to be voided instead of placed back in the hub (for comparison, mining a big accumulator stores in back in the hub).

edit: ah the minable.result is "solar-panel" instead of "big-solar-panel"

Ah yes thanks, I fixed it, my bad :)

60x? Bit much,eh?

I mean they also require 60 normal panels, some extra materials, are long to craft, and end up being 6.6x more space efficient, I don't think it's that unbalanced, but I'm totally open to discuss a better balance for it. For context, these are the same stats as the one in Bio Industries, as this was planned to be a sprite improvement for it initially.