Given they get around £2 million a day in subsidies plus other extras, I reckon they just build it in to their business model. Interest rate changes for the £7 billion plus they've had is probably a bigger hit.
That's just a leaf in the forest, the subsidy scheme was due to end in 2027 but has been extended to the end of the decade. That will cost the taxpayer/ bill payer an extra 4 billion.