The proposed lump sum payout to Renewable Heat Incentive (RHI) claimants should rise almost fourfold, a new report has concluded.

Consultants at Grant Thornton have calculated that owners of 99kW boilers should receive £122,927 in compensation if the scheme is shut down early.

It compares to proposals published by the Department for the Economy (DfE) in February which would see most RHI claimants receive either £35,000 or £35,500 for each 99kW boiler.

According to Grant Thornton, DfE have had “a series of omissions and missteps” in calculating compensation rates for scheme participants.

The consultants also state that if the scheme remains open, RHI tariffs should be revised upwards to a tier 1 tariff of 9.06p/kW and a tier 2 tariff of 2.95p/kW for 99kW boilers. The recommendation differs considerably from the current rates of 1.7p/kW for tier 1 and no payment for tier 2.

The report, which was commissioned by the Renewable Heat Association for NI and Balcas Timber Ltd, and co-funded by the UFU, states that DfE’s tariff calculations do not cover all costs associated with installing and maintaining a biomass boiler.