"I've heard rumors of photovoltaic systems that claim to be able to produce excess power to feed back into the grid, but haven't seen convincing reports that any "home systems" actually do produce net returnable power."

Not uncommon for solar to do the feed back game (Most of Aus is a lot warmer here - and nobody gets solar inverters big enough to run air conditioning!)- if you can afford it - there are various 'trials', but when the Govt max kick back is $8,000 and the setup will cost at least 2-3 times that much, with the special synced inverter, etc there's not a real big number of systems.

"In order to use your own solar-electric power while still drawing some from the grid, you would of course have to figure out how to connect the two systems while both are in operation; but I haven't seen details of how it's being done here, or much indication that power suppliers are willing to allow it in very many places."

I have a friend whose parents up the Qld North Coast have such a setup - was originally standalone - now the mains have been extended to them, but now they are looking at selling the inverter (not cheap!) - will run on generator only now if needed. The big hassle is water, but they now have a tank up the hill - took ages to convince the plumber that only ONE pipe was needed - water DOES flow in both directions! :-)