Plans to keep onshore wind farm grants going longer in Northern Ireland than the rest of the UK could cost households £16 extra in their bills.
Details have been provided to MLAs by the department of enterprise, trade and investment (DETI).
The executive is to continue with subsidies next year while a wider UK scheme will be ended early.
In Northern Ireland, there would also be an extra year’s grace for projects unable to be completed by 2017.
That would be in cases where the work had not been finished “due to no fault of their own”.
Customers would face extra charges to cover this.
Business customers would be hit hardest – the largest firms would see bills jump by £30,000.
Funding for what is known as the Renewables Obligation is by way of levies added to customer bills.
The department said the decision to continue support does not affect the executive’s finances as costs would be borne by consumers.
The subsidy has been the executive’s main policy measure to support the development of renewable energy.