The feed-in tariff (FIT) scheme for renewable electricity generation can make wind power a more attractive option. Under this scheme, a wind turbine receives a certain payment for every unit (kWh - a kilowatt-hour) of electricity generated from wind power, whether you use it yourself or sell it to the grid (for another 4.91p/kWh).
The FIT rate available from 1 January 2017 is 8.26 pence per kWh for wind turbines below 50kW peak output. For larger wind turbines see the full lists and updates for FIT rates on the Ofgem website.
For a 6kW wind turbine in a good windy location, the current FIT could work out to annual payments of around £1000, guaranteed for 20 years.
To be eligible for FIT income, the turbine has to be installed by a professional accredited under, and using equipment registered with, the Microgeneration Certification Scheme.
The following rough example illustrates the financial viability of domestic wind turbines in suitable locations (but it's important to keep in mind that energy yields and costs are very site-specific):
A domestic 2.5kW wind turbine is installed in a windy rural location. The turbine itself costs around £5,000, together with a 11m high tower and all necessary cabling, electronics and inverters the cost of the system comes to £15,000. In a good location, a wind turbine of this type can produce around 4,000 kWh per year (around 1,600 kWh per kW of rated capacity, i.e. a "capacity factor" of around 18%).
Say half (2,000 kWh) of the energy is used directly on-site, and half sold to the grid. Then the income from the turbine will be about £330 (8.26p/kWh x 4,000 kWh) from the generation tariff, plus about £100 (4.91p/kWh x 2,000 kWh) from the export tariff, plus £320 (16p/kWh * 2,000 kWh) savings on their electricity bill. This would add up to an annual combined income/saving worth about £750.
It is very difficult to estimate the maintenance costs for domestic wind turbines. Turbines are built to operate without much maintenance, but the inverter and some moving parts of the turbine may have to be replaced during its lifetime of around 20 years. If maintenance costs come to £100 per year, this might leave the net annual benefit at about £650. This may mean a financial pay-back time of around 20 years - so recouping costs within its lifetime. However, increasing electricity prices would lead to a shorter payback time.