24-hour or near 24-hour power delivery would be a big advantage to these space-based solar systems, compared to only mid-day daylight for terrestrial solar.
A modest amount of storage (for which there are a variety of options including conventional batteries, flow batteries, and pumped storage), as well as demand management (run your heat pump hot water and charge your EV in the middle of the day) is more than enough to deal with the intra-day mismatch between supply and demand.
That storage isn't cheap but is likely much cheaper than launching the equivalent amount of solar array into space, where the constant supply of power still means you need to either overbuild the array or build storage to supply peaks in demand.
The other thing to keep in mind is that few grids will be purely solar-powered; most large electricity grids will have wind in the mix as well.
Where the equation starts to look a little more appealing is in, say, Canada and northern Europe, where your energy demand is strongly seasonal, and solar output is strongly seasonal precisely the wrong way to meet that demand (unlike, say, Australia, where peak demand correlates reasonably well with solar energy availability).