The following levels of tariffs have been proposed on the basis that they pay an investment return of 12% for the case of heat pumps:
Ground source heat pumps:
Small installations (Up to 45 kW): 7 pence/kW
Medium Installations (45 - 350 kW): 5.5 pence/kW
Large installations (350 kW and above): 1.5 pence/kWh
Air source heat pumps:
Small installations (Up to 45 kW): 7.5 pence/kWh
Medium Installations (45 - 350 kW): 5.5 pence/kWh
Source: ammonia21.com