I just saw on ‘Ask this Old House’ that in Hawaii the utilities are no longer accepting power from private sources such as solar. So the individuals who have solar now have to install specialized batteries to store their power because there is no where else to send it.
It’s called “grid saturation”. With solar the idea is to make 24hrs worth of power in a 5-6hr time period each day. The grid capacity is only so big and it’s not that there is no place to send the excess power - it’s the fact that the wires are only so big and can handle only so much current. Which means there is no way to get the excess power onto the grid without upsizing equipment (ie. - mucho $$$).
Saturation levels have been raised to 100% (up from 25%) of the grid capacity for the time of day that solar generates.