If you did an hr you might get 300Wh
Elec is probably around £0.15/kWh
+ £0.03/kWh export
+ FiT Tariff (as its renewable – lets guess at £0.3/kWh)
So 0.3kWh x (£0.15 + £0.03 + £0.30)
=14.4p / hr
Gonna take a while to make your millions, especially if you eat anything in that hr 🙂