[mrweasel]

>Why is it a good idea to get off the grid?

It's not necessarily. If you use solar cells in your home, CO2 emission is something like 180g per kWh. In that case you'd be better of getting you power from the grid, if you can buy power from wind farms or nuclear power plant. It's better than coal, but only marginally better than natural gas.

If you happen to live in a country where you'll need heating for large parts of the year, it also pretty hard to beat the efficiency of a large district heating plant.