The wind turbines generate power by rotating a permanent magnet generator which generates three phase AC at the frequency of the turbine's rotation. The AC power from the generator is not only the wrong voltage to be connected to the local power grid, but also, as the wind speed changes so does the rotational speed of the turbine, and therefore the frequency of the power generated. The power from the generator therefore needs to be converted to DC and then fed into a special electronic device called an inverter, to ensure that it is always at the correct frequency and voltage for the local grid.
Any power you generate will be first used by your own property, thereby saving you the maximum amount possible on your electricity bill. Any excess energy your wind turbine generates, e.g. on windy days or at night, is "spilled" to the power grid and your electricity supplier pays you for it.
In order to charge your electricity supplier for any energy that you export to the grid, you need to have a new bi-directional electricity meter installed which will work both when you buy (import) and sell (export) electricity. Depending upon your local requirements, there may be additional meters needed to record energy generation to enable a claim for a Government subsidy.
Shown below is a simplified block diagram of how all the system components are connected in the EU.
Companies however shortly hope to offer an off-grid package which when combined with a battery pack, and optionally solar PV panels and/or a diesel generator will enable the generation of “mains” power where there is no grid connection. For more information on small wind turbines go to small wind turbines.
The inverter also provides essential safety features to control the power output from the turbine, and to automatically switch off the current if the grid connection should fail. This means that should the grid connection fail, the inverters will switch off their output and there is therefore no danger to any maintenance engineers fixing the fault. This does however mean that the wind turbine will produce no power to the property if the mains connection fails.