I think this is the case because the conduction method of the Solo is more indiscriminate in what it vaporizes than is the convection method of the TV. You'll notice that by the time the Solo is no longer producing thick visible vapor, that the material is very thoroughly toasted. Not just the trichomes, but the entire plant surface area. By comparison, because the convection method of the TV sees the chamber exposed to a more fleeting heat, only the most volatile of the oils is being evaporated off the load. I know I find that when a TV load is "spent", it still has a much more green appearance than a Solo load. I consider that a good thing, as I am not at all eager to be vaporizing the non-psychoactive, carbon-laden portions of the vegetative plant matter. That's why I hate the taste and vapor quality of my Solo by comparison to the TV. I would say that the size of the visible cloud is not at all correlative to the quality or potency of the vapor. Volatile oil vapor is much less visible than carbon-riddled vapor.