Why do they choose the systems which dont export power, which I assume are much more expensive? Is it a chicken and egg problem of unreliable grid, ie only when grid is powered, solar systems export power to the grid?
Worse yet. When grid is down, some grid-tied systems will not allow any local power use either.
Few years back, nearly all grid-tied inverters had this problem. Now situation is slowly improving, with "grid-interactive" systems which do allow local use of solar power with no grid.