This is all the next step. If they end up putting together an actual mission proposal, they can factor in power budgets for specific science instruments, sun angles and seasonality at the landing site, etc, but they're not quite there yet.
Not sure what you mean by limited operating time, though- if you mean that MSH has to spend 50% of its time charging, that's true, but relative to a rover, it can travel so much farther and faster that JPL is arguing it more than makes up for it.
Not sure what you mean by limited operating time, though- if you mean that MSH has to spend 50% of its time charging, that's true, but relative to a rover, it can travel so much farther and faster that JPL is arguing it more than makes up for it.