@evan went with strong yes, since we're running off our rootftop solar and pay for 100% of our energy from Green Mountain Power with their renewable energy rider -- aka, they buy RECs to offset non-renewable energy in their mix.
If you are grid attached, which I think is the best approach, you are going to have to rely upon accounting with REC purchases to get "clean".
It is a foundational truth, IMO, that this is a social system issue, and not an individual consumer issue. I do what i do to make the whole grid more reliable and to add more renewables to the mix for me and my neighbors -- not to clear my conscience.