@FrostCat said:@abarker said:Don't ask me what the reasoning for that is, I'm still trying to figure it out.It's not that hard: it means that you only have one set of wiring. If you're asking why grid-tied systems cut themselves off, it's in case a tree comes down down the street and cuts the wire there. If your grid-tie didn't cut itself off, you'd actually energize the street wire, and the linemen three houses down or whatever could get electrocuted by your solar panels. Although practically speaking the concern was always more about generators.
To me, it would make more sense to have a circuit in place to cut the outflow of power if the grid power stops. Then your solar panels could still provide power to your home during an outage, and still provide the benefit of selling excess to the grid when the grid is active.
The bigger problem is handling ground and phase as the grid goes up and down.
Edit:
Also selling to the gird is basically impossible in most US States - the best you can hope for is 0 aggregate cost. It, basically, comes down to rules about what is a provider from a "utility" standpoint.