No Brisvegas, it isn't always the case. My father in Perth regularly feeds excess energy into the grid with his 1.5 kW system. Your post is also misleading because the solar energy also reduces the grid usage. I'm not saying they are necessarily economic, but if they're not economic at the moment its because there is no level playing field. I do agree the government could provide more incentives to level up the playing field.
I should also say people living in MacMansions with MacPlasmas and MacFridges and MacAirconditioning and energy inefficient MacGlass windows may well use more energy than they generate. But then again these MacPeople probably aren't interested in solar energy anyway.
