In reply to KingStapo:
Grid connected feed-in tariff systems almost never work without grid power - partly because they lack any local storage (batteries) to regulate supply and demand, and partly because they can't isolate the AC they output from the grid, so their puny power would either be wiped out by grid demand or electrocute the linesman working to fix the problem.
Getting a solar backed up supply that is normally grid fed is more complicated, and is likely to introduce more failure prone pieces of equipment into the supply, and it still would be a limited supply under grid failure. Key words to search for are "grid tie" and "inverter charger".
SolarCity in the USA are making a big bruhah about their battery backed grid tie systems, and rather excitingly they use lithium ion batteries instead of deep cycle lead acid.
I am more interested in a small capacity solar as an independent back-up source than as a feed in, so I am considering a shed with a panel rated to a couple of hundred watts, a small lead acid battery and an inverter-charger. No grid tie nonsense and a single burried mains cable back to the house to run key devices. Also interested in getting a thermoelectric generator on the backboiler connected as a ~50W charging source to the lead acid. Fun hobby projects to approach with a definite air of caution!
Post edited at 21:55