Can't be arsed to find a relevant post in the B&Q wind turbine thread to tack this to but it appears you can get 7.8p/kWHr for exported electricity. Now as I only pay 7.191p/unit one one of my tarrifs...
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do suspect you would have to be on the Equipower tarrif but that is only 9.81p/unit, no standing charge, not even a hidden one, pay only for what you use, it's not a particulary expensive tarrif. If I bunged one of export meters on the supply that has Equipower and installed a suitable turbine I could well make a return as that meter only clocks up 1 unit/day on average.
Indeed I could link one meter to the other (via a power controller of some sort) and make still make money! Buying at 7.191 selling at 7.8, humm...