Is this grid-tie inverter (for solar, wind power) a bad idea?

[Filliam H. Muffman]

550 Watts is tiny. Paying an electrician to install it is going to eat up what it will save you for a long time. That is why most people install larger systems, to balance out the costs of the components against the savings. The best payback is for people that can push at least 2000 Watts to the grid (and minimize use during those times). Areas in California get about 30 cents from the utility during peak usage times.