RHIs are similar to FITs but apply to microgeneration technologies producing heat rather than electricity. The commercial and community scheme started first and is generous. The domestic scheme started in the spring of 2014 and is different from the commercial one. The priniciple used is for the RHI to allow householders to recover the capital cost over a seven year period. It includes solar thermal (hot water) systems, biomass boilers, biomass stoves using pellets and ground source heat pumps. Details of the scheme are here.